Topics in End of Year Exam Overview - Web viewThey contain lots of mitochondria to provide the ATP...

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Year 11b3 Yr9 content- BIOLOGY

Revision packName:___________________

Class:____________________

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ContentsTopics in End of Year Exam Overview..................................................................................................4

Specification Points covered in End of Year Exam: Checklist...............................................................5

4.1 Cell Biology..................................................................................................................................5

4.1.1 Cell Structure.........................................................................................................................5

4.1.2 Cell Division...........................................................................................................................9

4.1.3 Transport in cells.................................................................................................................10

4.2 Organisation..............................................................................................................................11

4.2.1 Principles of Organisation...................................................................................................11

4.2.2 Animal tissues, organs and organ systems.........................................................................11

Key Abbreviations in Specification for Skills..........................................Error! Bookmark not defined.

WS: Working Scientifically...................................................................Error! Bookmark not defined.

MS= Mathematical Skills......................................................................Error! Bookmark not defined.

AT= Use of Apparatus and Techniques................................................Error! Bookmark not defined.

Question terminology: What do the command words mean?..........................................................13

Equations that you will need to know................................................................................................14

Practice Questions based on specification points..............................................................................15

4.1.1 Cell Structure..........................................................................................................................15

4.1.1.1 Eukaryotes and prokaryotes............................................................................................15

4.1.1.2 Animal and plant cells......................................................................................................17

4.1.1.3 Cell specialisation.............................................................................................................18

4.1.1.4 Cell differentiation...........................................................................................................20

4.1.1.5 Microscopy.......................................................................................................................21

4.1.2 Cell Division............................................................................................................................22

4.1.2.1 Chromosomes..................................................................................................................22

4.1.2.2 Mitosis and the cell cycle.................................................................................................23

4.1.2.3 Stem cells.........................................................................................................................24

4.1.3 Transport in cells....................................................................................................................26

4.1.3.1 Diffusion...........................................................................................................................26

4.1.3.2 Osmosis............................................................................................................................29

4.1.3.3 Active Transport...............................................................................................................44

4.2.1 Principles of Organisation.......................................................................................................46

4.2.1.1 Organisational hierarchy.................................................................................................46

4.2.2 Animal tissues, organs and organ systems..............................................................................46

4.2.2.1 The human digestive system............................................................................................46

4.2.2.2 The heart and blood vessels.............................................................................................51

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4.2.2.3 Blood................................................................................................................................60

Answers to Specification Questions...................................................................................................63

4.1.1 Cell Structure..........................................................................................................................63

4.1.1.1 Eukaryotes and prokaryotes............................................................................................63

4.1.1.2 Animal and plant cells......................................................................................................64

4.1.1.3 Cell specialisation.............................................................................................................65

4.1.1.4 Cell differentiation...........................................................................................................67

4.1.1.5 Microscopy.......................................................................................................................67

4.1.2 Cell Division............................................................................................................................68

4.1.2.1 Chromosomes..................................................................................................................68

4.1.2.2 Mitosis and the cell cycle.................................................................................................69

4.1.2.3 Stem cells.........................................................................................................................70

4.1.3 Transport in cells....................................................................................................................71

4.1.3.1 Diffusion...........................................................................................................................71

4.1.3.2 Osmosis............................................................................................................................72

4.1.3.3 Active Transport...............................................................................................................80

4.2.1 Principles of Organisation.......................................................................................................81

4.2.1.1 Organisational hierarchy.................................................................................................81

4.2.2 Animal tissues, organs and organ systems..............................................................................82

4.2.2.1 The human digestive system............................................................................................82

4.2.2.2 The heart and blood vessels.............................................................................................85

4.2.2.3 Blood................................................................................................................................89

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Topics in End of Year Exam Overview

4.1 Cell Biology

4.1.1 Cell Structure 4.1.1.1 Eukaryotes and prokaryotes 4.1.1.2 Animal and plant cells 4.1.1.3 Cell specialisation 4.1.1.4 Cell differentiation 4.1.1.5 Microscopy

4.1.2 Cell Division 4.1.2.1 Chromosomes 4.1.2.2 Mitosis and the cell cycle 4.1.2.3 Stem cells

4.1.3 Transport in Cells 4.1.3.1 Diffusion 4.1.3.2 Osmosis 4.1.3.3 Active transport

4.2 Organisation

4.2.1 Principles of organisation 4.2.1.1 Organisational hierarchy

4.2.2 Animal tissues, organs and organ systems 4.2.2.1 The human digestive system 4.2.2.2 The heart and blood vessels 4.2.2.3 Blood

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Specification Points covered in End of Year Exam: Checklist

4.1 Cell Biology

4.1.1 Cell StructureRevision Points from Specification 4.1.1.1 Eukaryotes and prokaryotesPlant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus.Bacterial cells (prokaryotic cells) are much smaller in comparison. They have cytoplasm and a cell membrane surrounded by a cell wall. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids.SKILL: WS 4.4 Use prefixes centi, milli, micro and nano. SKILL: MS 2a, 2h Demonstrate an understanding of the scale and size of cells and be able to make order of magnitude calculations.4.1.1.2 Animal and plant cellsStudents should be able to explain how the main sub-cellular structures, including the nucleus, cell membranes, mitochondria, chloroplasts in plant cells and plasmids in bacterial cells are related to their functions. Most animal cells have the following parts: • a nucleus, which controls the activities of the cell • cytoplasm, in which most of the chemical reactions take place • a cell membrane, which controls the passage of substances into and out of the cell • mitochondria, which is where aerobic respiration takes place • ribosomes, which are where protein synthesis occurs. In addition to the parts found in animal cells, plant cells often have: • chloroplasts, which absorb light to make food by photosynthesis • a permanent vacuole filled with cell sap. Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell.ACTIVITY: Observing and drawing plant and animal cells under the microscope4.1.1.3 Cell specialisationStudents should be able to, when provided with appropriate information, explain how the structure of different types of cell relate to their function in a tissue, an organ or organ system, or the whole organism. Cells may be specialised to carry out a particular function: • sperm cells, nerve cells and muscle cells in animals • root hair cells, xylem and phloem cells in plants.

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4.1.1.3 Specialist Animal Cells information sheetNerve cells

Nerve cells are specialised to carry electrical impulses around the body of an animal (Figure 1). They provide a rapid communication system between the different parts of the body. They have several adaptations including:

Lots of dendrites to make connections to other nerve cells. An axon that carries the nerve impulse from one place to another. They can be very long –

the axon of a nerve cell in a blue whale can be up to 25 m long! The longest axon in your body runs from the base of your spine to your big toe.

The nerve endings or synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals. They contain lots of mitochondria to provide the ATP needed to make the transmitter chemicals.

Muscle cells

Muscle cells are specialised cells that can contract and relax. Striated (striped) muscle cells work together in tissues called muscles (Figure 2). They contract and relax in pairs to move the bones of the body so you can move about, and allow birds and insects to fly. Smooth muscle cells form one of the layers of tissue in your digestive system and they contract to squeeze the food through your gut.

Striated muscle cells have three main adaptations:

They contain special proteins that slide over each other making the fibres contract. They contain many mitochondria to produce the ATP needed for the chemical reactions that

take place as the cells contract and relax. They can store glycogen, a chemical that can be broken down and the products used in

cellular respiration by the mitochondria to provide the ATP needed for the fibres to contract.

Sperm cells

Sperm cells are usually released a long way from the egg they are going to fertilise. They contain the genetic information from the male parent.

Depending on the type of animal, sperm cells need to move through water or the female reproductive system to reach an egg. Then they have to break into the egg. Sperm cells have several adaptations to make all this possible:

A long tail whips from side to side to help move the sperm through the female reproductive system.

The middle section is full of mitochondria, which provide the ATP needed for the tail to work.

The acrosome stores digestive enzymes for breaking down the outer layers of the egg. A large nucleus contains the genetic information to be passed on.

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4.1.1.3 Specialist Plant Cells Information SheetRoot hair cells

You find root hair cells close to the tips of growing roots. Plants need to take in lots of water (and dissolved mineral ions). The root hair cells help them to take up water and mineral ions more efficiently. Root hair cells are always relatively close to the xylem tissue. The xylem tissue carries water and mineral ions up into the rest of the plant. Mineral ions are moved into the cell by active transport. Root hair cells have three main adaptations:

They greatly increase the surface area available for water to move into the cell. They have a large permanent vacuole that speeds up the movement of water by osmosis

from the soil across the root hair cell. They have many mitochondria that provide the ATP needed for the active transport of

mineral ions into the root hair cells.

Photosynthetic cells

One of the ways plants differ from animals is that plants can make their own food by photosynthesis. There are lots of plant cells that can carry out photosynthesis – and lots that cannot. Photosynthetic cells usually have a number of adaptations including:

They contain specialised green structures called chloroplasts containing chlorophyll that trap the light needed for photosynthesis.

They are usually positioned in continuous layers in the leaves and outer layers of the stem of a plant so they absorb as much light as possible.

They have a large permanent vacuole that helps keep the cell rigid as a result of osmosis. When lots of these rigid cells are arranged together to form photosynthetic tissue they help support the stem. They also keep the leaf spread out so it can capture as much light as possible.

Xylem cells

Xylem is the transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots. The xylem is also important in supporting the plant. The xylem is made up of xylem cells that are adapted to their functions in two main ways:

The xylem cells are alive when they are first formed but a special chemical called lignin builds up in spirals in the cell walls. The cells die and form long hollow tubes that allow water and mineral ions to move easily through them, from one end of the plant to the other.

The spirals and rings of lignin in the xylem cells make them very strong and help them withstand the pressure of water moving up the plant. They also help support the plant stem.

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Phloem Phloem is the specialised transport tissue that carries the food made by photosynthesis around the body of the plant. It is made up of phloem cells that form tubes rather like xylem cells, but phloem cells do not become lignified and die. The dissolved food can move up and down the phloem tubes to where it is needed. The adaptations of the phloem cells include:

The cell walls between the cells break down to form special sieve plates. These allow water carrying dissolved food to move freely up and down the tubes to where it is needed.

Phloem cells lose a lot of their internal structures but they are supported by companion cells that help to keep them alive. The mitochondria of the companion cells provide the ATP needed to move dissolved food up and down the plant in phloem.

Revision Points from Specification 4.1.1.4 Cell differentiationAs an organism develops, cells differentiate to form different types of cells. Most types of animal cell differentiate at an early stage whereas many types of plant cells retain the ability to differentiate throughout life. In mature animals, cell division is mainly restricted to repair and replacement. As a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a specialised cell.4.1.1.5 MicroscopyAn electron microscope has much higher magnification and resolving power than a light microscope. This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures. Limited to the differences in magnification and resolution.SKILL: Explain how electron microscopy has increased understanding of subcellular structures. WS 4.4 WS 1.1 Use prefixes centi, milli, micro and nano. SKILL: MS 1a, 1b, 2h, 3b Carry out calculations involving magnification, real size and image size using the formula: magnification = size of image/size of real object

4.1.2 Cell DivisionRevision Points from Specification 4.1.2.1 ChromosomesThe nucleus of a cell contains chromosomes made of DNA molecules.

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Each chromosome carries a large number of genes. In body cells the chromosomes are normally found in pairs.SKILL: WS 1.2 Use models and analogies to develop explanations of how cells divide.4.1.2.2 Mitosis and the cell cycle

Cells divide in a series of stages called the cell cycle. One of these stages is mitosis where the DNA, which has already been copied, divides.

During the cell cycle the genetic material is doubled and then divided into two identical cells. Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. One set of chromosomes is pulled to each end of the cell and the nucleus divides. Finally the cytoplasm and cell membranes divide to form two identical cells.

Knowledge of the stages of mitosis is not required. Cell division by mitosis is important in the growth and

development of multicellular organisms. Students should be able to recognise and describe situations in given contexts where mitosis is occurring.

4.1.2.3 Stem cellsA stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation. Stem cells from human embryos and adult bone marrow can be cloned and made to differentiate into many different types of human cells. Knowledge and understanding of stem cell techniques are not required. Treatment with stem cells may be able to help conditions such as diabetes and paralysis.In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment. The use of stem cells has potential risks such as transfer of viral infection, and some people have ethical or religious objections. Stem cells from meristems in plants can be used to produce clones of plants quickly and economically. • Rare species can be cloned to protect from extinction. • Large numbers of identical crop plants with special features such as disease resistance.SKILL: WS 1.3 Evaluate the practical risks and benefits, as well as social and ethical issues, of the use of stem cells in medical research and treatments.

4.1.3 Transport in cellsRevision Points from Specification 4.1.3.1 DiffusionSubstances may move into and out of cells across the cell membranes via diffusion.

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Diffusion is the spreading of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration. Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney.Factors which affect the rate of diffusion are:• the difference in concentrations (concentration gradient) • the temperature • the surface area of the membrane.A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism. Students should be able to explain how the small intestine and lungs in mammals, gills in fish, and the roots and leaves in plants, are adapted for exchanging materials. In multicellular organisms the smaller surface area to volume ratio means surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organism’s needs. The effectiveness of an exchange surface is increased by: • having a large surface area • a membrane that is thin, to provide a short diffusion path • (in animals) having an efficient blood supply • (in animals, for gaseous exchange) being ventilated.SKILL: MS 1c, 5c Calculate and compare surface area to volume ratios.4.1.3.2 OsmosisWater may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.SKILL: Required practical 1: investigate the effect of salt or sugar solutions on plant tissue. AT 1, 3 and 5 MS 1c, 2b, 4a, 4b, 4c, 4d Calculate percentages, use negative numbers and construct graphs.4.1.3.3 Active TransportActive transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.Students should be able to link the structure of a root hair cell to its function.Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth. It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration. Students should be able to explain the differences between diffusion, osmosis and active transport.SKILL: There are links with this content to Cell specialisation. WS 1.4 Students should be able to describe how kidney dialysis works. WS 1.5 Use of isotonic drinks and high energy drinks in sport.

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4.2 Organisation4.2.1 Principles of Organisation

Revision Points from Specification 4.2.1.1 Organisational hierarchy

Cells are the basic building blocks of all living organisms. A tissue is a group of cells with a similar structure and function. Organs are aggregations of tissues performing specific functions. Organs are organised into organ systems, which work together to

form organisms.SKILL: MS 1c Students should be able to develop an understanding of size and scale in relation to cells, tissues, organs and systems.

4.2.2 Animal tissues, organs and organ systems

Revision Points from Specification 4.2.2.1 The human digestive systemThis section assumes knowledge of the digestive system studied in Key Stage 3 science. The digestive system is an example of an organ system in which several organs work together to digest and absorb food. Students should be able to relate knowledge of enzymes to Metabolism Enzymes:• are biological catalysts that speed up chemical reactions in living organisms • are large proteins • catalyse a specific reaction due to the shape of the active site • are denatured by high temperature and extremes of pH due to changes in the shape of the active site • have an optimum temperature • have an optimum pHThe ‘lock and key theory’ is a simplified model of enzyme action. Students should be able to recall the sites of production and the action of amylase, proteases and lipases. Students should be able to understand simple word equations but no chemical symbol equations are required. Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream. Carbohydrases break down carbohydrates to simple sugars. Amylase is a carbohydrase which breaks down starch. Proteases break down proteins to amino acids. Lipases break down lipids (fats) to glycerol and fatty acids.SKILL: WS 1.2 Use other models to explain enzyme action.The products of digestion are used to build new carbohydrates, lipids and proteins. Some glucose is used in respiration.SKILL: AT 5 Measure rates of reaction by different methods.Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.

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Required practical 2: investigate the effect of a factor on the rate of an enzyme-controlled reaction.4.2.2.2 The heart and blood vessels Students should know the structure and functioning of the human heart and lungs, including how lungs are adapted for gaseous exchange. The heart is an organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle pumps blood around the rest of the body. Knowledge of the blood vessels associated with the heart is limited to the aorta, vena cava, pulmonary artery, pulmonary vein and coronary arteries. Knowledge of the names of the heart valves is not required. Knowledge of the lungs is restricted to the trachea, bronchi, alveoli and the capillary network surrounding the alveoli. The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker. Artificial pacemakers are electrical devices used to correct irregularities in the heart rate. The body contains three different types of blood vessel: • arteries • veins • capillaries Students should be able to explain how the structure of these vessels relates to their functions.SKILL: MS 1a, 1c Use simple compound measures such as rate. Carry out rate calculations.4.2.2.3 Blood Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended. • Plasma transports proteins and other chemical substances around the body. • Red blood cells contain haemoglobin which binds to oxygen to transport it from the lungs to the tissues. • White blood cells help to protect the body against infection. • Platelets are fragments of cells which initiate the clotting process at wound sites. Students should be able to recognise different types of blood cells in a photograph or diagram, and explain how they are adapted to their functions.SKILL: AT 7 Observing and drawing blood cells seen under a microscope. WS 1.5 Evaluate risks related to use of blood products.

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Question terminology: What do the command words mean?

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Equations that you will need to know

Image ¿ Actual (real ) ¿Magnification

Acutal (real ) ¿ Image ¿¿Magnification ¿

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(mm)

1000

1000

Micrometre

(nm)

1000

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Practice Questions based on specification points

4.1.1 Cell StructureDifficulty level (Easy= Grade 1-3; Medium= Grade 4-6; Hard=Grade 7-9)

Questions Write your answer4.1.1.1 Eukaryotes and prokaryotes

Easy Q1) State what plant and animal cells have in common. (3 marks)

Easy Q2) Which is smaller a bacteria cell or a plant cell? (1 mark)

Medium Q3) Define a plasmid. (1 mark)

Hard Q4) Compare and

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contrast an animal, plant and bacterial cell (6 marks)

Easy Q5) 2.2m into cm (3 marks)

Medium Q6) 2.2m into mm (3 marks)

Medium Q7) 2.2mm into micrometres (3 marks)

Medium Q8) 2.2mm into nanometres (3 marks)

Hard Q9) 3.124cm into nanometres (3 marks)

Medium Q10) If the scale is 1 cm equals 5 µm. How large is a cell measuring 8cm in diameter? Answer in micrometres. (3 marks)

Hard Q11) If the scale is 1 cm equals 10 µm. How large is a cell across with a radius of 10cm? Answer in nanometres. (5 marks)

Hard Q12) If the scale is 3 cm equals 5 µm. How

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large is a cell measuring 1 cm in its length? Answer in micrometres.

4.1.1.2 Animal and plant cellsEasy Q13) Which one does

not contain chloroplast?

a) Algae cellb) Palisade cellc) Root hair cell

Q14) Explain how the following main sub-cellular structures are related to their functions.

a) a nucleus b) cytoplasm c) a cell

membraned) mitochondria e) ribosomes f) chloroplasts g) a permanent

vacuole h) a cell wall

a) a nucleus

b) cytoplasm

c) a cell membrane

d) mitochondria

e) ribosomes

f) chloroplasts

g) a permanent vacuole

h) a cell wall

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Medium/Hard Q15) What is the criteria needed to draw plant and animal cells properly under a microscope. (7 marks)

4.1.1.3 Cell specialisationMedium Q16) Explain why

sperm cells have tails? (2 marks)

Medium Q17) Explain why sperm cells have a lot of mitochondria in their head. (2 marks)

Medium/Hard Q18) Explain the key adaptations of nerve cells (3 marks)

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Easy Q19) State what muscle cells are specialised for. (2 marks)

Hard Q20) Explain three ways that muscles cells are adapted for their role. (3 marks)

Medium/Hard Q21) Explain how root hair cells are adapted for their function. (3 marks)

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Easy/Medium Q22) Describe the use of xylem vessels. (3 marks)

Easy Q23) Identify the two main parts of Phloem (2 marks)

Difficulty level (Easy= Grade 1-3; Medium= Grade 4-6; Hard=Grade 7-9)

Question Write your answer4.1.1.4 Cell differentiation

Easy Q24) Fill in the blanks

Word bank: differentiate, replacement, cells, specialised, plant, repair, animal

As an organism develops, cells differentiate to form

different types of ____________. Most types of

________________ cell differentiate at an early stage

whereas many types of _______________ cells retain

the ability to _________________________

throughout life. In mature animals, cell division is

mainly restricted to _______________ and

_______________________. As a cell differentiates it

acquires different sub-cellular structures to enable it to

carry out a certain function. It has become a

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____________________________ cell.

4.1.1.5 MicroscopyHard Q25) Suggest why

research scientists prefer using an electron microscope. (4 marks)

Medium Q26) What are the limitations of an electron microscope? (2 marks)

Hard

Q27) Scale: 1 cm equals 500 nm. Work out the image size. Answer in micrometres (5 marks)

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Q28)

4.1.2 Cell Division


Question Write your answer4.1.2.1 Chromosomes

Easy Q29) Write the following in size order from largest to smallest. (5 marks)CellDNANucleusGeneChromosome

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4.1.2.2 Mitosis and the cell cycleEasy Q30) Where does mitosis

occur? (1 mark)

Hard Q31) Describe Mitosis and explain why it is important. (6 marks)

Medium/Hard Q32) Suggest why the process of Mitosis is sometimes known as asexual reproduction. (3 marks)

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4.1.2.3 Stem cellsMedium Q33) State the definition of

a stem cell. (3 marks)

Easy Q34) Identify two places where stem cells are found in humans (2 marks)

Easy Q35) Name two conditions which Scientists believe the use of stem cells will help. (2 marks)

Hard Q36) Evaluate the practical risks and benefits, as well as social and ethical issues, of the use of stem cells in medical research and treatments. (6 marks)

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Easy Q37) State where stem cells are found in plants. (1 mark)

Hard Q38) Suggest how farmers and conservationists should use stem cells from plants to benefit them. (6 marks)

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4.1.3 Transport in cellsDifficulty level (Easy= Grade 1-3; Medium= Grade 4-6; Hard=Grade 7-9)

Question Write your answer4.1.3.1 Diffusion

Easy Q39) State the definition of diffusion. (3 marks)

Easy Q40) Name substances that are diffused in humans. (3 marks)

Medium Q41) Describe the factors which affect the rate of diffusion (3 marks)

Easy Q42) Delete as appropriate:A single-celled organism has a relatively large/small surface area to volume ratio. (1 mark)

A single-celled organism has a relatively large/small surface area to volume ratio.

Medium Q43) Explain how the small intestine is adapted for diffusion. (3 marks)

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Medium/ Hard

Q44) Explain how gas exchange takes place in the lungs. (5 marks)

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Hard Q45) Explain how gills in fish are adapted for diffusion. (4 marks)

Medium Q46) Explain how leaves are adapted for exchanging materials.

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Hard Q47) Explain how the effectiveness of an exchange surface can be increased. (4 marks)

Easy/Medium

Q48) Complete the table below (24 marks)

4.1.3.2 OsmosisEasy Q49) Define osmosis.

(3 marks)

Hard Q50) Suggest how you

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Length of each side (L) cm

Area of each face (L2) cm2

Surface area of the whole cube (L2) x 6cm2

Volume of the cube (L3)cm3

Surface area to volume ratio

Surface area cm2

volume cm3

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could investigate the effect of sugar solutions on plant tissue. (6 marks)

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HardQ51) A cook prepares a fresh fruit salad by

cutting up a variety of fruits and placing them in a bowl with layers of sugar in between. After two hours the fruit is surrounded by syrup (concentrated sugar solution).

Explain, as fully as you can, why syrup (concentrated sugar solution) was produced after two hours. (4 marks)

MediumQ52) If a solution is isotonic, what does this

mean? (2 marks)

MediumQ53) If a plant cell is hypotonic, what will

happen? (2 marks)

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Q55) The drawing shows part of a root hair cell.

(a) Use words from the list to label the parts of the root hair cell.

cell membrane cell wall cytoplasm nucleus vacuole(4)

(b) The diagram shows four ways in which molecules may move into and out of a cell. The dots show the concentration of molecules.

The cell is respiring aerobically.Which arrow, A, B, C or D represents:

(i) movement of oxygen molecules; ....................

(ii) movement of carbon dioxide molecules? ....................(2)

(c) Name the process by which these gases move into and out of the cell.

...................................................................................................................................(1)

(Total 7 marks)

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Q56) Some students set up this experiment to investigate osmosis. They filled two pieces of dialysis [visking] tubing with different liquids and left them both in a beaker of 5% sucrose solution for an hour.

2 0 % suc rose so lu tion

D ia ly s is (v isk in g ) tu b in g

D is tilled w ate r

5 % su cro se so lu tio n

Tu b e 1 Tu b e 2

(a) Describe and explain the likely results after one hour.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

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...................................................................................................................................

...................................................................................................................................(6)

(b) Describe two examples where osmosis is used in living things.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(2)

(Total 8 marks)

Q57) In fish and chip shops, potatoes are cut into chips several hours before they are cooked.

The amount of water in the chips must be kept constant during this time.

To keep the water in the chips constant, the chips are kept in salt solution.

A student investigated the effect of different concentrations of salt solution on the mass of chips.

He weighed each of five chips. He placed each chip into a different concentration of salt solution. After one hour he removed the chips, then reweighed them.

His results are shown in the table.

Concentration of saltsolution 0 M 0.5 M 1 M 2 M 3 M

Mass of chip at start ingrams 2.6 2.8 2.8 2.5 2.6

Mass of chip after onehour in grams 2.7 2.8 2.7 2.3 2.1

(a) (i) In which concentration of salt solution did the chip gain mass?

........................ M(1)

(ii) Complete the sentence by drawing a ring around the correct answer in the box.

The chip gained mass because water entered by digestion

osmosis

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respiration

(1)

(b) In which concentration of salt solution should the chips be kept?

........................ M

Give a reason for your answer.

................................................................................................................................... (2)

(c) How could the student have made his investigation more reliable?

...................................................................................................................................

...................................................................................................................................(Total 5 mark)

Q58) Students investigated the effect of different concentrations of sodium chloride solution on discs cut from an apple. They weighed each disc and then put one disc into each of a range of sodium chloride solutions of different concentrations. They left the discs in the solutions for 24 hours and then weighed them again. Their results are shown in the table.

Concentration of sodium chloride solution / mol dm–3

Mass of disc at start / g

Mass of disc at end / g

Ratio of mass at start to mass at end

0.00 16.1 17.2 0.94

0.15 19.1 20.2 0.95

0.30 24.3 23.2 1.05

0.45 20.2 18.7 1.08

0.60 23.7 21.9

0.75 14.9 13.7 1.09

(a) (i) Calculate the ratio of the mass at the start to the mass at the end for the disc placed in the 0.60 mol dm–3 sodium chloride solution.

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Answer ......................................(1)

(ii) The students gave their results as a ratio. What is the advantage of giving the results as a ratio?

.............................................................................................................

.............................................................................................................

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.............................................................................................................

.............................................................................................................(2)

(iii) The students were advised that they could improve the reliability of their results by taking additional readings at the same concentrations of sodium chloride.

Explain how.

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................(2)

(b) (i) The students used a graph of their results to find the sodium chloride solution with the same water potential as the apple tissue. Describe how they did this.

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................(2)

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(ii) The students were advised that they could improve their graph by taking additional readings. Explain how.

.............................................................................................................

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.............................................................................................................

.............................................................................................................(2)

(Total 9 marks)

Q59) A student investigated the effect of putting cylinders cut from a potato into sodium chloride solutions of different concentration. He cut cylinders from a potato and weighed each cylinder. He then placed each cylinder in a test tube. Each test tube contained a different concentration of sodium chloride solution. The tubes were left overnight. He then removed the cylinders from the solutions and reweighed them.

(a) Before reweighing, the student blotted dry the outside of each cylinder. Explain why.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................(2)

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The student repeated the experiment several times at each concentration of sodium chloride solution. His results are shown in the graph.

(b) The student made up all the sodium chloride solutions using a 1.0 mol dm–3

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sodium chloride solution and distilled water.

Complete the table to show how he made 20 cm3 of a 0.2 mol dm–3 sodium chloride solution.

Volume of 1.0 mol dm–3 sodium chloride solution Volume of distilled water

(1)

(c) The student calculated the percentage change in mass rather than the change in mass. Explain the advantage of this.

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (2)

(d) The student carried out several repeats at each concentration of sodium chloride solution. Explain why the repeats were important.

......................................................................................................................

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......................................................................................................................

......................................................................................................................

......................................................................................................................(2)

(e) Use the graph to find the concentration of sodium chloride solution that has the same water potential as the potato cylinders.

.............................. mol dm–3

(1)(Total 8 marks)

Q60) The diagram shows a carrot.

A group of students investigated the effect of sucrose concentration on the length of cylinders cut from a carrot.

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(a) The students used a cork borer to cut cylinders from the carrot. Describe how the students should cut these cylinders to make sure that this was a fair test and would produce reliable results.

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (2)

(b) They measured the initial length of each cylinder then placed the cylinders into test tubes containing different concentrations of sucrose solution. Bungs were placed in the tubes and the tubes were left overnight. Explain why the bungs were placed in the tubes.

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................(2)

(c) The students then measured the final lengths of the carrot cylinders. Their results are shown in the table.

Concentration of sucrose / mol dm–3

0.0 1.4

0.2 1.4

0.4 1.2

0.6 1.1

0.8 0.9

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(i) The students used these results to find the concentration of sucrose that has the same water potential as the carrot cylinders. Describe how they could have done this.

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................(2)

(ii) Was it important in this investigation that the carrot cylinders had the same initial length? Explain your answer.

.............................................................................................................

............................................................................................................. (1)(Total 7 marks)

Q61) Tradescantia is a house plant. There are small hairs on its flowers. These hairs are made of cells. Figure 1 shows the appearance of cells from one of these hairs after 20 minutes in distilled water. Figure 2 shows cells from another hair after 20 minutes in a solution of potassium nitrate.

Figure 1 (in distilled water)

Figure 2 (in potassium nitrate solution)

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(a) What does Figure 2 suggest about the permeability of the plasma membranes surrounding these cells?

......................................................................................................................

......................................................................................................................(1)

(b) What is present in the space labelled F? Explain your answer.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................(2)

(c) How would the water potential of the sap in the vacuole of cell E differ from the water potential of the sap in the vacuole of cell D? Explain your answer.

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......................................................................................................................

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......................................................................................................................(3)

(Total 6 marks)

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Question Write your answer4.1.3.3 Active Transport

Easy Q62) Define active transport. (2 marks)

Medium Q63) Explain how mineral ions are absorbed into plants and why they’re important. (3 marks)

Medium Q64) Explain how sugar molecules are absorbed into the blood from the gut and how sugar molecules are used in the body. (3 marks)

Hard Q65) Compare and Contrast the processes of diffusion, osmosis and active transport. (6 marks)

Hard Q66) Explain how a kidney dialysis machine works. (6 marks)

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Question Write your answer4.2.1.1 Organisational hierarchy

Easy Q70) What do you call a group of cells with a similar structure and function? (1 mark)

Easy Q71) Write down the following from smallest to largest: (4 marks)CellOrganOrgan systemTissue



Question Write your answer4.2.2.1 The human digestive system

Easy/Medium

Q72) Enzymes: Fill in the blanks (10 marks)• are b_____________ c___________ that speed ___ chemical reactions in living organisms • are large p__________ • catalyse a specific reaction due to the shape of the a_________ s_____ • are d_______________ by high t_______________ and extremes of p__ due to changes in the shape of the active site • have an ____________ temperature • have an optimum pH

Enzymes: Fill in the blanks

• are b_____________ c___________ that

speed ___ chemical reactions in living

organisms

• are large p__________

• catalyse a specific reaction due to the shape

of the a_________ s_____

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• are d_______________ by high

t_______________ and extremes of p__ due

to changes in the shape of the active site

• have an ____________ temperature

• have an optimum pH

Medium Q73) Describe the lock and key mechanism of an enzyme. (4 marks)

Easy Q74) Name one role of glucose in the body. (1 mark)

Hard Q75) Explain the role of bile. (6 marks)

Easy Q76) What do carbohydrase

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enzymes do? (2 marks)

Easy Q77) Explain what amylase does. (2 marks)

Easy Q78) Explain what lipase does. (2 marks)

Easy Q79) Explain what protease does. (2 marks)

Medium Q80) Georgina investigated the effect of protease on egg white.In test tube 1 she put a small chunk of cooked egg white into a test tube and added 25ml of protease.In test tube 2 she put the same mass of egg white with 25ml of water.She left both tubes at 37ºC for 10 minutes and then observed the change in their appearance.a) Why did she include the tube with water? (1 mark)b) Why did she keep the tubes at 37 ºC? (1 mark)c) Give two control variables that she used (2 marks)d) Explain what she would see in each test tube and give an explanation why(3 marks)e) Georgina’s teacher was not happy with they dependent variable she used. Suggest a dependent variable for this investigation that would give more reliable evidence. (1 mark)

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Q82) (57 marks)

Name of Organ Main function Enzymes present

Main food digested and products

Mouth

Oesophagus

Stomach

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Q81

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Liver

Gall bladder

Pancreas

Small intestine

Large intestine

Rectum

Anus


Question Write your answer4.2.2.2 The heart and blood vessels

Easy Q83) What does the circulatory system do? (1 mark)

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Medium Q84) Explain what the circulatory system consists of. (5 marks)

Easy Q85) What are valves? (1 mark)

Medium Q86) Explain how arteries are adapted to carrying blood under high pressure. (3 marks)

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Medium Q87) Explain how veins are adapted to carrying blood under low pressure. (3 marks)

Medium Q88) Why are capillaries so small? (1 mark)

Medium Q89) Explain how the capillaries are adapted to exchange substances. (2 marks)

Hard Q90) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

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Describe the passage of blood through the heart. (6 marks)

Medium Q91) Explain why the circulatory system is often regarded as a ‘double circulation’. (3 marks)

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EasyQ92) The diagram shows a section

through a human heart.

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A

B

C

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Which of the blood vessels labelled A to D

(a) takes blood from the heart to the muscles of the arms and legs; (1)

(b) is a vein which contains oxygenated blood? (1)

EasyQ93) Name the structures which form the gas exchange surface in the lungs. (1 mark)

MediumQ94) State three ways in which the lungs are adapted for the exchange of gases. (3 marks)

Hard Q95) Identify where the group cells are located that control the natural resting heart rate and act as a pacemaker. (1 mark)

Easy Q96) Describe the basic use of an Artificial pacemaker. (1 mark)

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Easy Q97) Label these structures. (6 marks)

Q98) The graphs show some changes in pressure and volume during part of a cardiac cycle.

P ressu re

Vo lu m eo fv en tric le

A o rta

Ven tric le

X Y ZTim e

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(a) Describe what the graphs show about the pressure and volume in the ventricle between times X and Y.

...................................................................................................................................

...................................................................................................................................(1)

(b) At point Y, the valve between the aorta and the ventricle opens. Use the information about pressure on the graph to explain why.

...................................................................................................................................

...................................................................................................................................(1)

(c) Explain the changes in the volume of the ventricle between times X and Z.

...................................................................................................................................

...................................................................................................................................

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...................................................................................................................................(3)

(Total 5 marks)

Q99) The graph shows changes in the volume of blood in the left ventricle as the heart beats.

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1 4 0

1 2 0

1 0 0

8 0

6 0

00 0 .2 0 .4 0 .6 0 .8 1 .0 1 .2 1 .4

A

Vo lu m e /c m

Tim e / s

3

(a) (i) The horizontal line labelled A on the graph shows when blood is leaving the ventricle. Explain, in terms of blood pressure, why blood does not flow back into the atrium during this period.

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.........................................................................................................................

.........................................................................................................................(2)

(ii) Draw a horizontal line on the graph, to show the period in one cardiac cycle when the muscle in the wall of the ventricle is relaxed. Label this line with the letter B.

(1)

(b) (i) Draw a horizontal line on the graph to show one complete cardiac cycle. Label this line with the letter C.

(1)

(ii) Use line C to calculate the number of times the heart beats in one minute. Show your working.

Answer ...................................(2)

Q100) This diagram shows a human heart seen from the front.

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B C

A D

X

Y

(a) (i) Which one or more of vessels A to D contains oxygenated blood?

.........................................................................................................................(1)

(ii) During a cardiac cycle, the pressure of the blood in vessel C is higher than the pressure of the blood in vessel B. Explain what causes this difference in pressure.

.........................................................................................................................

.........................................................................................................................(1)

(b) What does the diagram suggest about the pressure in the atria compared to the pressure in the ventricles at the stage in the cardiac cycle represented in the diagram? Explain your answer.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................(2)

Q101) The table shows the breathing rates of 5 people, A, B, C, D and E as they walk at different speeds.

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(a)Calculate the mean (average) breathing rate for the five people when walking at 3 km per hour. Show your working.

Answer....................................

(b) What is the relationship between speed of walking and breathing rate?

.......................................................................................................................................................................

(c) For person A, what change in speed of walking increases the breathing rate by 10%?

.......................................................................................................................................................................

(d) Calculate the percentage increase in the breathing rate when person D changes from walking at 1 km per hour to 4 km per hour. Show your working.

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Walking speed (km per hour)

Breathing rate (Breaths per minute)

Person A Person B Person C Person D Person E

0 16 15 16 14 14

1 17 16 17 15 16

2 20 18 19 17 18

3 21 19 20 19 21

4 22 20 23 20 23

5 27 23 28 23 26

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Answer.............................


Question Write your answer4.2.2.3 Blood

Easy Q102) What are the four main components of blood? (4 marks)

Medium Q103) Explain what the plasma does. (2 marks)

Hard Q104) Explain how red blood cells are adapted to carry oxygen. (6 marks)

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Medium Q105) Identify type of blood cell A and explain role in the body (2 marks)

Q106) Explain the role of platelets. (2 marks)

Medium Q107) Blood carries digested food around the body. Give three other functions of the blood. (3 marks)

Medium Q108) Sunil trips and falls why running.He grazes the palm of his hand.He cuts his leg badly on a piece of glass.

Explain why the graze does not

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bleed very much but the leg bleeds a lot. (3 marks)


Describe how the bleeding from the graze would stop. (2 marks)


The blood from Sunil’s leg is bright red and pumping out. Which type of blood vessel has been cut? (2 marks)

Answers to Specification Questions

4.1.1 Cell StructureDifficulty level (Easy= Grade 1-3; Medium= Grade 4-6; Hard=Grade 7-9)

Questions Write your answer4.1.1.1 Eukaryotes and prokaryotes

Easy Q1) State what plant and animal cells have in common. (3 marks)

Plant and animal cells (eukaryotic cells) have a cell membrane (1), cytoplasm (1) and genetic material enclosed in a nucleus (1).

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Easy Q2) Which is smaller a bacteria cell or a plant cell? (1 mark)

Bacteria cell (1)

Medium Q3) Define a plasmid. (1 mark) small ring of DNA (1)

Hard Q4) Compare and contrast an animal, plant and bacterial cell (6 marks)

Animal, Plant and Bacteria: cytoplasm and cell membraneAnimal and Plant: nucleus (eukaryotic), mitochondria, ribosomesPlant and Bacteria: cell wall (plant made from cellulose; bacteria made from protein)Plant: permanent vacuole and chloroplasts.Bacteria: no nucleus (prokaryotic) just single DNA loop and there may be one or more small rings of DNA called plasmids.

Easy Q5) 2.2m into cm (3 marks)Marks for sum; answer and unit

2,2 x 100 = 220 cm

Medium Q6) 2.2m into mm (3 marks)Marks for sum; answer and unit

2.2 x 1000 = 2 200 mm

Medium Q7) 2.2mm into micrometres (3 marks)Marks for sum; answer and unit

2.2 x 1000 = 2 200 µm

Medium Q8) 2.2mm into nanometres (3 marks)Marks for sum; answer and unit

2.2 x 1 000 000 = 2 200 000 nm

Hard Q9) 3.124cm into nanometres (3 marks)Marks for sum; answer and unit

3.124 x 10 000 000 = 31 240 000 nm

Medium Q10) If the scale is 1 cm equals 5 µm. How large is a cell measuring 8cm in diameter? Answer in micrometres. (3 marks)Marks for sum; answer and unit

8 x 5 = 40 µm

Hard Q11) If the scale is 1 cm equals 10 µm. How large is a cell across with a radius of 10cm? Answer in nanometres. (5 marks)

10 µm= 10 x 1000= 10 000 nmDiameter = 2 x 10= 2020 x 10 000 = 200 000 nm

Hard Q12) If the scale is 3 cm equals 5 µm. How large is a cell measuring 1 cm in its length? Answer in micrometres.

3 cm = 5 µm1 cm= 5/3 µm = 1. 67 µm (accept 1.7 µm)

4.1.1.2 Animal and plant cellsEasy Q13) Which one does not contain

chloroplast? C- Root hair cell

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d) Algae celle) Palisade cellf) Root hair cell

Q14) Explain how the following main sub-cellular structures are related to their functions.

i) a nucleus j) cytoplasm k) a cell membranel) mitochondria m) ribosomes n) chloroplasts o) a permanent vacuole p) a cell wall

a) a nucleus, which controls the activities of the cell

b) cytoplasm, in which most of the chemical reactions take place

c) a cell membrane, which controls the passage of substances into and out of the cell

d) mitochondria, which is where aerobic respiration takes place

e) ribosomes, which are where protein synthesis occurs.

f) chloroplasts, which absorb light to make food by photosynthesis

g) a permanent vacuole filled with cell sap.

h) Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell.

Medium/Hard Q15) What is the criteria needed to draw plant and animal cells properly under a microscope. (7 marks)

1. Drawing with a sharp pencil; no colour or pen

2. Drawing fills most of the paper3. Clear continuous lines provide

outline of image only; no shading

4. Magnification given5. Title of object/ cell given6. Labels and label lines

horizontal and straight7. Accuracy shown in drawing

4.1.1.3 Cell specialisationMedium Q16) Explain why sperm cells have tails? (2

marks)Sperm cells have tails to help them swim toward the egg

Medium Q17) Explain why sperm cells have a lot of Sperm cells need lots of

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mitochondria in their head. (2 marks) mitochondria so respiration can occur and so they have enough energy to move.

Medium/Hard Q18) Explain the key adaptations of nerve cells (3 marks)

Lots of dendrites to make connections to other nerve cells.

An axon that carries the nerve impulse from one place to another. They can be very long – the axon of a nerve cell in a blue whale can be up to 25 m long! The longest axon in your body runs from the base of your spine to your big toe.

The nerve endings or synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals. They contain lots of mitochondria to provide the ATP needed to make the transmitter chemicals.

Easy Q19) State what muscle cells are specialised for. (2 marks)

Muscle cells are specialised cells that can contract and relax.

Hard Q20) Explain three ways that muscles cells are adapted for their role. (3 marks)

They contain special proteins that slide over each other making the fibres contract.

They contain many mitochondria to produce the ATP needed for the chemical reactions that take place as the cells contract and relax.

They can store glycogen, a chemical that can be broken down and the products used in cellular respiration by the mitochondria to provide the ATP needed for the fibres to contract.

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Medium/Hard Q21) Explain how root hair cells are adapted for their function. (3 marks)

They greatly increase the surface area available for water to move into the cell.

They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell.

They have many mitochondria that provide the ATP needed for the active transport of mineral ions into the root hair cells.

Easy/Medium Q22) Describe the use of xylem vessels. (3 marks)

Xylem is the transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots. The xylem is also important in supporting the plant.

Easy Q23) Identify the two main parts of Phloem (2 marks)

Sieve plates and companion cells


Question Write your answer4.1.1.4 Cell differentiation

Easy Q24) Fill in the blanks

Word bank: differentiate, replacement, cells, specialised, plant, repair, animal

As an organism develops, cells differentiate to form different types of ____________. Most types of ________________ cell differentiate at an early stage whereas many types of _______________ cells retain the ability to

As an organism develops, cells differentiate to form different types of cells. Most types of animal cell differentiate at an early stage whereas many types of plant cells retain the ability to differentiate throughout life. In mature animals, cell division is mainly restricted to repair and replacement. As a cell

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_________________________ throughout life. In mature animals, cell division is mainly restricted to _______________ and _______________________. As a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a ____________________________ cell.

differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a specialised cell.

4.1.1.5 MicroscopyHard Q25) Suggest why research scientists

prefer using an electron microscope. (4 marks)

An electron microscope has much higher magnification (1) and resolving power (1) than a light microscope. This means that it can be used to study cells in much finer detail (1). This has enabled biologists to see and understand many more sub-cellular structures (1).

Medium Q26) What are the limitations of an electron microscope? (2 marks)

Limited to the differences in magnification and resolution.

Hard Q27) Scale: 1cm equals 500 nm. Work out the image size. Answer in micrometres. (5 marks)

Height: 3.3cmImage size= real size x magnificationReal size = 3.3 x 500 = 1 650 nmImage size= 1 650 x 400 = 660 000 nm660 000 ÷ 1000 = 660 µm

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4.1.2 Cell Division


Question Write your answer4.1.2.1 Chromosomes

Easy Q29) Write the following in size order from largest to smallest. (5 marks)CellDNANucleusGeneChromosome

CellNucleusChromosomeGeneDNA

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Eyepiece lens

Tube

Focussing knob

Arm Support (Handle)

Objective lens

Stage

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4.1.2.2 Mitosis and the cell cycleEasy Q30) Where does mitosis occur?

(1 mark)Everywhere apart from the sex organs.

Hard Q31) Describe Mitosis and explain why it is important. (6 marks)

One of these stages is mitosis where the DNA, which has already been copied, divides.

During the cell cycle the genetic material is doubled and then divided into two identical cells. Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. One set of chromosomes is pulled to each end of the cell and the nucleus divides. Finally the cytoplasm and cell membranes divide to form two identical cells.

Cell division by mitosis is important in the growth and development of multicellular organisms.

Medium/Hard Q32) Suggest why the process of Mitosis is sometimes known as asexual reproduction. (3 marks)

Mitosis produces genetically identical daughter cells. Asexual reproduction is where a clone (genetically identical organism) is produced. Therefore because there is no variation it must occur by Mitsosis.

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4.1.2.3 Stem cellsMedium Q33) State the definition of a stem cell.

(3 marks)A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Easy Q34) Identify two places where stem cells are found in humans (2 marks)

Human embryos and adult bone marrow

Easy Q35) Name two conditions which Scientists believe the use of stem cells will help. (2 marks)

Treatment with stem cells may be able to help conditions such as diabetes and paralysis.

Hard Q36) Evaluate the practical risks and benefits, as well as social and ethical issues, of the use of stem cells in medical research and treatments.

In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment. The use of stem cells has potential risks such as transfer of viral infection, and some people have ethical or religious objections.

Easy Q37) State where stem cells are found in plants. (1 mark)

meristems

Hard Q38) Suggest how farmers and conservationists should use stem cells from plants to benefit them. (6 marks)

Stem cells from meristems in plants can be used to produce clones of plants quickly and economically. • Rare species can be cloned to protect from extinction. • Large numbers of identical crop plants with special features such as disease resistance, drought tolerance, predator tolerant, weed tolerant etc

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4.1.3 Transport in cellsDifficulty level (Easy= Grade 1-3; Medium= Grade 4-6; Hard=Grade 7-9)

Question Write your answer4.1.3.1 Diffusion

Easy Q39) State the definition of diffusion. (3 marks)

Diffusion is the spreading of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration across a partially permeable membrane.

Easy Q40) Name substances that are diffused in humans. (3 marks)

Oxygen, carbon dioxide, urea

Medium Q41) Describe the factors which affect the rate of diffusion (3 marks)

Factors which affect the rate of diffusion are:• the difference in concentrations (concentration gradient) • the temperature • the surface area of the membrane.

Easy Q42) Delete as appropriate:A single-celled organism has a relatively large/small surface area to volume ratio. (1 mark)

A single-celled organism has a relatively large/small surface area to volume ratio.

Medium Q43) Explain how the small intestine is adapted for diffusion. (3 marks)

Small Intestine is adapted by• having a large surface area due to villi and micro-villi • a membrane that is thin, to provide a short diffusion path • having an efficient blood supply

Medium/ Hard

Q44) Explain how gas exchange takes place in the lungs. (5 marks)

Gas exchange occurs in the alveoli where oxygen diffuses into the blood capillaries because the concentration of oxygen is higher in the alveoli than the blood capillaries. Carbon dioxide diffuses out of the blood capillaries because the concentration is higher in the blood capillaries than outside in the alveoli. Carbon dioxide is then breathed out.

Hard Q45) Explain how gills in fish are adapted for Gills are adapted for diffusion by

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diffusion. (4 marks) • having a large surface area • a membrane that is thin, to provide a short diffusion path • having an efficient blood supply • being ventilated for effective gaseous exchange.

Medium Q46) Explain how leaves are adapted for exchanging materials.

Leaves are adapted for the exchange of materials by: • having a large surface area • a membrane that is thin, to provide a short diffusion path

Hard Q47) Explain how the effectiveness of an exchange surface can be increased. (4 marks)

The effectiveness of an exchange surface is increased by: • having a large surface area • a membrane that is thin, to provide a short diffusion path • (in animals) having an efficient blood supply • (in animals, for gaseous exchange) being ventilated.

Easy/Medium

Q48) Complete the table below (24 marks)

4.1.3.2 OsmosisEasy Q49) Define osmosis. (3

marks)Water may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a

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Length of each side (L) cm

Area of each face (L2) cm2

Surface area of the whole cube (L2) x 6cm2

Volume of the cube (L3)cm3

Surface area to volume ratio

Surface area cm2

volume cm3

1 1 6 1 6:12 4 24 64 3:83 9 54 729 2:274 16 96 64 3:25 25 150 125 6:56 36 216 216 1:1

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partially permeable membrane.

Hard Q50) Suggest how you could investigate the effect of sugar solutions on plant tissue. (6 marks)

1) Prepare 10cm3 of each of 0.8M, 0.4M, 0.2M, 0.15M and 0.075M sucrose solutions, each in a separate tube. Be careful to mix the water and the more dense strong sugar solutions thoroughly. Add a sixth tube of water to complete the series.

2) Label each solution.

3) Cut up about 10g potato tissue into small cubes about 2mm square. Weigh accurately about 0.75g potato tissue into each empty tube. Blot the tissue before weighing and be sure the balance is carefully zeroed. Record the weight in each tube accurately.

4) When all the weighings are complete, cover the tissue in each tube with the corresponding solution (5cm3 is sufficient) and note the time. ie. cover the tissue in the 0.2M tube with 0.2M sucrose etc. Note how the potato looks when this is complete.

5) Leave the tubes for 15 minutes, swirling occasionally. (Time to make a diagram of the technique so far.)

6) Remove the tissue from each tube, blot it on a paper towel and weigh each amount separately; making sure that the balance is carefully zeroed before each weighing. (Six weighings, one from each tube.)

7) Make a table of Initial weight; Final weight; and Final weight/Initial weight for each concentration.

8) Plot a graph of Final weight/Initial weight against concentration.

Using your graph, predict the concentration of sucrose which is in equilibrium with the potato tissue and hence calculate the Water Potential of the tissue

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HardQ51) A cook prepares a fresh fruit salad by

cutting up a variety of fruits and placing them in a bowl with layers of sugar in between. After two hours the fruit is surrounded by syrup (concentrated sugar solution).

Explain, as fully as you can, why syrup (concentrated sugar solution) was produced after two hours. (4 marks)

ideas thatsugar has dissolved in moisture (on surface of fruit)this solution more concentrated than solution inside fruitosmosis / diffusionmovement of water out of fruitthrough partially permeable membrane (of fruit cells)

any four for 1 mark each

allow explanations in terms of concentrations of water molecules for full marks

MediumQ52) If a solution is isotonic, what does this

mean? (2 marks)

Isotonic is when the concentration of particles (water) is equal both inside and outside of the cell

MediumQ53) If a plant cell is hypotonic, what will

happen? (2 marks)

Hypotonic: the particles (water) move into the cell because the concentration of water is higher outside of the cell than inside so moves down a concentration gradient

MediumQ54) Define hypertonic. (2 marks) Hypertonic: the particles

(water) move out of the cell because the concentration of water is higher inside of the cell than outside so moves down a concentration gradient

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Q55) (a) (cell) wall 4(cell) membranecytoplasmvacuole

for 1 mark each

(b) (i) A 2

(ii) B

for 1 mark each

(c) diffusion (reject osmosis) 1

for 1 mark[7]

Q56) (a) award 3 marks per tube for each key idea 3

for tube 1:

expands or gets firmer or bigger orinflates

it gains water

because the concentration of water is less than its surroundings

make sure answer is about water movement and not sucrose solution

for tube 2 3

gets floppy or flaccid or contracts

it loses water

because the concentration of water is greater than its surroundings

(b) any 2 from: 2

uptake of water by root (hair) ormovement from cell to cell withinplant

do not credit references to diffusion unless it is clear that the candidate is referring to the diffusion of water

guard cell function

maintain turgor

water absorption in the large intestine

reabsorption of water from thenephron or collecting duct or inkidney or osmoregulation in kidney

allow osmosis in other animals if some use is shown[8]

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Q57) (a) (i) 0 1

(ii) osmosis 1

(b) 0.5 1

no change in mass / weight 1

allow ‘chip / it stays the same’

or

no (net) osmosis / same amount of water in and out

(c) repeat / use more chips in each solution 1

allow use of other people’s results

do not allow ‘get more results’ unqualified

do not allow leave longer / use more concentrations / better instrumentation

[5]

Q58) (a) (i) 1.08;Must be to 3 significant figures, as in the table

1

(ii) Allows comparison/shows proportional change;Neutral: sizes/amounts

Idea that discs had different starting masses/weights;Neutral: different masses

2

(iii) (Allows)Accept: outliers instead of anomalies

Anomalies to be identified/effect of anomalies to be reduced/effect of variation in data to be minimised;

Reject: idea of not recording anomalies/preventing anomalies from occurring

A mean to be calculated;Neutral: average

2

(b) (i) Plot (sodium chloride) concentration against ratio/drawline of best fit;

Reject: if wrong axes or type of graph

Find (sodium chloride concentration from the graph) wherethe ratio is 1/there is no change in mass;

2

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(ii) Line/curve of best fit is more reliable/precise;Neutral: graph

Intercept/point where line crosses axis is more reliable/precise;Reject: references to ‘more accurate’

OR

Can plot SD values/error bars;

(To show) variability about the mean/how spreadout the results are;

2[9]

Q59) (a) Water will affect the mass/only want to measure water taken up or lost;

Amount of water on cylinders varies/ensures same amountof water on outside;

Neutral: removes waterAccept: ‘(sodium chloride) solution’ for waterDo not accept ‘sodium chloride’Neutral: refs. to fair testing

2

(b) 4 cm3 (of 1.0 mol dm–3 sodium chloride solution) and 16 cm3 (ofdistilled water);

Reject: factors and multiples of these figures e.g. 2 cm3 and 8 cm3, as final volume should be 20 cm3

1

(c) Allows comparison/shows proportional change;

Idea that cylinders have different starting masses/weights;Reject: if comparison is in context of the start and final mass of the same cylinderNeutral: different massesNeutral: different starting sizes

2

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(d) (Allows) anomalies to be identified/ignored/effect of anomalies to bereduced/effect of variation in data to be minimised;

Makes the average/mean/line of best fit more reliable/allows concordantresults;

Accept: ‘outliers’ instead of anomaliesQ Reject: abnormalitiesReject: idea of not recording anomalies/preventing anomalies from occurringAccept: ‘cancels out anomalies’ as bottom line responseQ Reject: makes the average/mean more accurateNeutral: makes the average/mean more validNeutral: makes ‘it’/results/conclusion more reliable

2

(e) 0.35 (mol dm–3)1

[8]

Q60) (a) Lengthways/down the root;

Through one tissue only / through same part / sameproportion of tissues;

2

(b) To prevent the water from evaporating / prevent evaporation;

Changing the concentrations / water potential (of solution);2

(c) (i) Plot data on a graph;

Find (sucrose concentration) from the graph where the ratio is 1;2

(ii) No, because the results are given as a ratio/as a proportion ofinitial length;

1[7]

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Q61) (a) partially/selectively permeable accept semi-permeableallows water to pass through but not potassium nitrate/solute;

1

(b) potassium nitrate (solution);cell wall permeable;

2

(c) water potential more negative/lower in cell E; water removed;greater solute/sap concentration (in cell);

3[6]

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Question Write your answer4.1.3.3 Active Transport

Easy Q62) Define active transport. (2 marks)

Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.

Medium Q63) Explain how mineral ions are absorbed into plants and why they’re important. (3 marks)

Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.

Medium Q64) Explain how sugar molecules are absorbed into the blood from the gut and how sugar molecules are used in the body. (3 marks)

Active transport allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.

Hard Q65) Compare and Contrast the processes of diffusion, osmosis and active transport. (6 marks)

All: methods of moving particles across a semi permeable membraneDiffusion and Osmosis: no energy required (passive); particles move from a high concentration to a low concentration.Diffusion: general termOsmosis: water movementActive transport: requires energy as going from low concentration to high concentration

Hard Q66) Explain how a kidney dialysis machine works. (6 marks)

- The blood vessels in the arm are connected to a dialysis machine.

- In the dialysis machine a person’s blood flows between partially permeable membranes.

- The dialysis fluid contains the same concentration of useful substances as the blood.

- This ensures that glucose and useful mineral ions are not lost.

- There is a high concentration of urea in the person’s blood, and no urea in the dialysis fluid.

- There is a concentration gradient of urea between the blood and the dialysis fluid.

- Urea passes out from the blood into the dialysis fluid by diffusion.

- Treatment by dialysis restores the concentrations of dissolved substances in the blood to normal levels.

It has to be carried out at regular intervals.Easy Q67) What three

substances do most soft drinks contain? (3 marks)

Most soft drinks contain water, sugar and ions.

Easy Q68) Why do sports drinks

Water and ions replace the water and ions lost during sweating.

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Question Write your answer4.2.1.1 Organisational hierarchy

Easy Q70) What do you call a group of cells with a similar structure and function? (1 mark)

A tissue is a group of cells with a similar structure and function.

Easy Q71) Write down the following from smallest to largest: (4 marks)CellOrganOrgan systemTissue

CellTissueOrganOrgan system



Question Write your answer4.2.2.1 The human digestive system

Easy/Medium

Q72) Enzymes: Fill in the blanks (10 marks)• are b_____________ c___________ that speed ___ chemical reactions in living organisms • are large p__________ • catalyse a specific reaction due to the shape of the a_________ s_____ • are d_______________ by high t_______________ and extremes of p__ due to changes in the shape of the active site • have an ____________ temperature • have an optimum pH

Enzymes:• are biological catalysts that speed up chemical reactions in living organisms • are large proteins • catalyse a specific reaction due to the shape of the active site • are denatured by high temperature and extremes of pH due to changes in the shape of the active site • have an optimum temperature • have an optimum pH

Medium Q73) Describe the lock and key mechanism of an enzyme. (4 marks)

Substrate and enzyme collide (1) fits into/has a complementary shape to active site (1) forms an enzyme-substrate complex (1) reaction occurs when substrate and enzyme are connected (1) product released after

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reaction (1) enzyme free to undergo another reaction/fit with another substrate (1)

Easy Q74) Name one role of glucose in the body. (1 mark)

respiration

Hard Q75) Explain the role of bile. (6 marks) Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.

Easy Q76) What do carbohydrase enzymes do? (2 marks)

Carbohydrases break down carbohydrates to simple sugars.

Easy Q77) Explain what amylase does. (2 marks)

Amylase is a carbohydrase which breaks down starch.

Easy Q78) Explain what lipase does. (2 marks)

Lipases break down lipids (fats) to glycerol and fatty acids.

Easy Q79) Explain what protease does. (2 marks)

Proteases break down proteins to amino acids.

Medium Q80) Georgina investigated the effect of protease on egg white.In test tube 1 she put a small chunk of cooked egg white into a test tube and added 25ml of protease.In test tube 2 she put the same mass of egg white with 25ml of water.She left both tubes at 37ºC for 10 minutes and then observed the change in their appearance.a) Why did she include the tube with water? (1 mark)b) Why did she keep the tubes at 37 ºC? (1 mark)c) Give two control variables that she used (2 marks)d) Explain what she would see in each test tube and give an explanation why(3 marks)e) Georgina’s teacher was not happy with they dependent variable she used. Suggest a dependent variable for this investigation that would give more reliable evidence. (1 mark)

Georgina investigated the effect of human protease on egg white.In test tube 1 she put a small chunk of cooked egg white into a test tube and added 25ml of protease.In test tube 2 she put the same mass of egg white with 25ml of water.She left both tubes at 37ºC for 10 minutes and then observed the change in their appearance.

a) It was a control / So she could check that it was the protease breaking down the egg white

b) Because that is human body temperature / It is the optimum temperature of the enzymec) Same volume of liquid / same mass of egg white / same temperature d) The chunk of egg white in test tube 1 would have got smaller as the protease enzyme would have broken down the protein into soluble amino acids. The chunk in test tube 2 would have stayed the same because there was no protease

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present to break down the protein.e) Change in mass of egg white chunk.

Q82) 57 marks

Name of Organ Main function Enzymes present

Main food digested and products

MouthPhysically digests food by grinding with teeth (1)Releases digestive juices containing amylase (1)

Amylase (1) Starch (1) to glucose (1)

Oesophagus Moves food down to stomach by peristalsis (1)

None (1) None (1)

Stomach Muscular tissue helps to physically grind food by churning (contracting and relaxing muscles) (1)Digestive juices released from glandular tissue (1)Acid kills microbes and makes conditions ideal for enzyme (1)Acidic conditions (1)Epithelial tissue lines inside and out (1)

Protease (1) Protein (1) to amino acids (1)

Liver Produces bile (1) None (1) None (1)

Gall bladder Stores bile (1)Released into small intestine (1)Neutralises acid from stomach (1)

None (1) None (1)

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Q81)

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Makes condition suitable for enzymes to work (1)Emulsifies fat (1)

Pancreas Makes digestive juices which contain enzymes (1)

Lipase (1)Protease (1)Amylase (1)

Fats and oils (1) to fatty acid and glycerol (1)Proteins (1) to amino acids (1)Starch (1) to sugars (1)

Small intestine Makes enzymes to digest food (1)Absorbs soluble food molecules (1)

Lipase (1)Protease (1)Amylase (1)

Fats and oils (1) to fatty acid and glycerol (1)Proteins (1) to amino acids (1)Starch (1) to sugars (1)

Large intestine Absorbs remaining water (1) None (1) None (1)

Rectum Stores faeces (1)Faeces contains dead cells, fibre and bacteria (1)

None (1) None (1)

Anus Excretes faeces (1) None (1) None (1)


Question Write your answer4.2.2.2 The heart and blood vessels

Easy Q83) What does the circulatory system do? (1 mark)

The circulatory system transports substances around the body.

Medium Q84) Explain what the circulatory system consists of. (5 marks)

- the heart - which is the muscular pump that keeps the blood moving around the body

- the blood - which carries the substances around the body

- the arteries - which carry blood away from the heart

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- the veins - which return blood to the heart

- the capillaries - which are tiny blood vessels that are close to the body’s cells where exchanges can happen

Easy Q85) What are valves? (1 mark) Valves in the heart ensure that blood flows in the correct direction.

Medium Q86) Explain how arteries are adapted to carrying blood under high pressure. (3 marks)

- thick walls - to resist the high pressure of the blood

- a thick layer of elastic fibres – to allow the artery to stretch when a surge of blood passes through it, and then recoil in between heart beats to maintain blood pressure

- a thick layer of muscle within the wall – to allow blood to be diverted to where it is needed in the body

Medium Q87) Explain how veins are adapted to carrying blood under low pressure. (3 marks)

- thin walls as they have blood with a lower pressure flowing through them

- one-way valves in them to prevent blood flowing back in the opposite direction

- larger lumen than arteries to maximise blood flow despite the lower pressure

Medium Q88) Why are capillaries so small? (1 mark) To slow the blood and allow exchange of nutrients and oxygen.

Medium Q89) Explain how the capillaries are adapted to exchange substances. (2 marks)

- Walls are one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs.

- They have permeable walls, so substances can diffuse in and out.

Hard Q90) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Describe the passage of blood through the heart. (6 marks)

Deoxygenated blood arrives at the left-hand side of the heart:

1. It enters the heart through the vena cava.

2. Blood flows into the right atrium.

3. Blood is pumped into the right ventricle.

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4. Blood is pumped out of the heart, along the pulmonary artery, to the lungs where gaseous exchange occurs.

Oxygenated blood arrives at the right-hand side of the heart:

1. It enters the heart through the pulmonary vein.

2. Blood flows into the left atrium.

3. Blood is pumped into the left ventricle.

Blood is pumped out of the heart, along the aorta, to the rest of the body.

Medium Q91) Explain why the circulatory system is often regarded as a ‘double circulation’. (3 marks)

- Humans have a double circulation, in which the heart acts as a double pump

- The right side pumps blood at low pressure to the lungs to release carbon dioxide and pick up oxygen

- The left side pumps blood at high pressure to the body to release oxygen and pick up carbon dioxide.

EasyQ92) The diagram shows a section

through a human heart. (a) B/aorta; 1

(b) D/pulmonary vein;

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A

B

C

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Which of the blood vessels labelled A to D

(a) takes blood from the heart to the muscles of the arms and legs; (1)

(b) is a vein which contains oxygenated blood? (1)

EasyQ93) Name the structures which form the gas exchange surface in the lungs. (1 mark)

Alveoli

MediumQ94) State three ways in which the lungs are adapted for the exchange of gases. (3 marks)

Three of:

- large surface area;

- moist surfaces (for gas exchange);

- well supplied with blood vessels;

- thin-walled air sacs/alveoli;

Hard Q95) Identify where the group cells are located that control the natural resting heart rate and act as a pacemaker. (1 mark)

Right atrium

Easy Q96) Describe the basic use of an Artificial pacemaker. (1 mark)

Artificial pacemakers are electrical devices used to correct irregularities in the heart rate.

Easy Q97) Label these structures. (6 marks) 1- Thorax2- Abdomen3- Trachea4- bronchi/bronchus5- intercostal muscles

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6- diaphragm

Q98) (a) Pressure increases and volume stays constant;

(b) Pressure in ventricle (becomes) higher than pressure in aorta;[Or converse]

(c) ventricle contracts;Produces increase in pressure;Blood leaves venticle/ goes into aorta (and volume falls);Through open valve; max 3

Q99) (a) (i) Blood pressure in ventricle higher than in atrium;(Causes) atrioventricular / mitral / (bi)cuspid / valve between atriumand ventricle to shut; 2

(ii) Line labelled B from 0.2 to 0.7s;(Ignore line from 1.0 to 1.4s.)

(b) (i) Line labelled C from 0.2 to 1.0s,(Accept any other line between equivalent points in consecutivecycles.)

(ii) 8.060

= 75 beats per minute - method mark 60length of cycle given by candidate;

- answer mark - calculation giving correct answer;

Q100) (a) (i) C and D; 1

(ii) left ventricle with thicker wall/more muscle / (muscle in) left ventriclecontracts more forcefully/beats more strongly;

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(b) higher in atria/lower in ventricles;atrioventricular valves/valves between atria and ventricles open;

(position of valves must be identified. Do not accept an unqualified reference to valves. Assume pronouns refer to atria.)

Q101 (a)21 + 19 + 20 + 19 + 21; = 20 breaths per minute; 2

5

(b) As speed of walking increases, rate of breathing increases; 1

(c) From 2 km per hour to 4 km per hour; 1

(d) 5 x 100;

15 = 33%;


Question Write your answer4.2.2.3 Blood

Easy Q102) What are the four main components of blood? (4 marks)

Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended.

Medium Q103) Explain what the plasma does. (2 marks)

Plasma transports proteins and other chemical substances around the body.

Hard Q104) Explain how red blood cells are adapted to carry oxygen. (6 marks)

- Red blood cells have no nucleus.

- They are packed with a red pigment called haemoglobin.

In the lungs: - Oxygen diffuses into the red

blood cells.- Haemoglobin combines with

oxygen to form oxyhaemoglobin.

In the other organs:

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- Oxyhaemoglobin splits up into haemoglobin and oxygen.

- Oxygen diffuses out of the red blood cell.

They have a biconcave shape. This increases their surface area to increase rate of diffusion across the cell membrane.

Medium Q105) Identify type of blood cell A and explain role in the body

(2 marks)

White blood cells (1) help to protect the body against infection. (1)

Q106) Explain the role of platelets. (2 marks)

Platelets are fragments of cells (1) which initiate the clotting process at wound sites. (1)

Medium Q107) Blood carries digested food around the body. Give three other functions of the blood. (3 marks)

Defence against illnesses, blood clotting, gas transport, waste removal.

Medium Q108) Sunil trips and falls why running.He grazes the palm of his hand.He cuts his leg badly on a piece of glass.Explain why the graze does not bleed very much but the leg bleeds a lot. (3 marks)

The capillary damage for a graze is not as deep, very little blood loss, (1) however if a larger vessel in the leg is cut the blood loss could be substantial. (1) In case of a cut artery (1) it could be life threatening.


Describe how the bleeding from the graze would stop. (2 marks)

When blood becomes exposed to the air the chemicals in the blood react and the platelets (1) form a clot (scab) (1) which covers the injured area.

Medium Q110) Sunil trips and falls why running.He grazes the palm of his hand.He cuts his leg badly on a piece of

An artery has been cut.(1) Arterial blood gets it’s colour from the combination of oxygen and the pigment, haemoglobin. (1)

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glass.

The blood from Sunil’s leg is bright red and pumping out. Which type of blood vessel has been cut? (2 marks)

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