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Answer all questions.

1 Which structures are measured using these units?

10-3 m 10-6 m 10-9 m

A chloroplast ribosome nucleus

B nucleus chloroplast xylem vessel

C ribosome xylem vessel chloroplast

D xylem vessel nucleus ribosome

2 What describes the features of an electron microscope and its use?

maximum magnification resolution / nm specimen used

A x 2 500 250 dead

B x 25 000 0.5 living

C x 250 000 0.5 dead

D x 500 000 250 living

3 The diameter of living cells varies considerably.

The typical diameters are a eukaryote, such as a white blood cell 1.5 × 101 μm a prokaryote, such as Streptococcus 7.5 × 102 nm

Use these measurements to find the maximum number of each cell type which could fit along a line 1 cm long.

number of white blood cells number of Streptococcus cells

A 6.7 × 103 1.3 × 105

B 6.7 × 102 1.3 × 104

C 6.7 × 101 1.3 × 103

D 6.7 × 100 1.3 × 102

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4 Lactose is a disaccharide present in the milk of mammals.

How will a baby mammal benefit from having this sugar, instead of a monosaccharide, in the milk?

A Condensation of disaccharides enables rapid production of glycogen.

B Disaccharides can be transported across membranes for more rapid absorption.

C Disaccharides have a higher energy value than triglycerides.

D Hydrolysis of the glycosidic bond gives a gradual release of monosaccharide.

5 Which statement describes how the molecular structure of starch is suited to its function?

A Amylose has a branched structure and amylopectin is coiled to give a compact molecule for transport

B In the formation of amylose and amylopectin, many condensation reactions allow the release of stored energy.

C In the formation of amylose and amylopectin, many condensation reactions allow the release of stored energy.

D The final amylose / amylopectin complex is insoluble and does not affect the osmotic properties of the cell.

6 Which row shows the types of bond found at different levels of protein structures?

level of protein structure

bonds

key

= present = absent

peptide hydrogen ionic hydrostatic

A primary

B secondary

C tertiary

D quaternary

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7 Which combination of procedures would not be used in a food test?

use heatuse biuret

reagentuse Benedict’s

reagentboil with dilute acid

A

B

C

D

8 The enzyme lysozyme secreted from tear glands forms deposits on contact lenses.Which ingredient would be effective in a contact lens cleaner for removing these deposits?

A Ethanol

B Lysosomes

C pH buffers

D Proteases

9 The rate of enzyme catalysed reactions in human cells is regulated.

Which of the following may be involved in such regulation?

1 a change in enzyme concentration2 a change in substrate concentration3 inhibition by the final product of the reaction

A 1 only B 3 only C 1 and 2 only D 1, 2 and 3

10 A metabolic pathway is

What would be the effect of adding a small amount of a non-competitive inhibitor of enzyme 2?

A Enzyme 2 would be partially denatured.

B Substance X would increase in concentration.

C Substance Y would no longer be formed.

D The initial reactant would no longer be metabolised.

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11 The fluid mosaic model proposes that plasma membranes consist of

A a protein bilayer with phospholipids interspersed between the protein molecules.

B two layers of lipid with protein between them.

C two layers of protein with lipid between them.

D a phospholipid bilayer with protein molecules interspersed between the phospholipid molecules.

12 Which role of the cell surface membrane is not a result of the properties of the phospholipids?

A to allow cytokinesis to occur in mitotic cell division

B to allow entry and exit of the water-soluble gases, oxygen and carbon dioxide

C to allow phagocytosis of a bacterium into cells

D to allow surface membranes to stabilise by binding with water molecules

13 Visking tubing is an artificial partially permeable membrane used to demonstrate diffusion. Glucose molecules can pass through the pores in the membrane which are approximately 2.4 nmin diameter.

Which of the following could pass through the pores?

1 bacteria

2 haemoglobin

3 ribosomes

4 glycogen

A 2 only B 1 and 3 only C 2 and 4 only D none of these

14 In general, eukaryotic cells undergo division much slower than prokaryotic cells.

What is the reason for this?

A Eukaryotes break down the nuclear membrane during mitosis.

B Eukaryotes have many more mitochondria than prokaryotes.

C Prokaryotes do not contain any centrioles.

D Prokaryotic cells are a lot smaller than eukaryotic cells.

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15 Refer to the following diagram, which shows events in the cell cycle:

In human beings, one of the known functions of a protein called p53 is to monitor the DNA andregulate cell division. If the DNA is damaged, p53 will prevent DNA replication and will allowthe cell cycle to continue only after the DNA has been successfully repaired.

According to the information above, in a cell with damaged DNA the p53 protein is likely to

A prevent progression of the cell from the G2 phase to the M phase.

B prevent progression of the cell from the C phase to the G1 phase.

C allow the cell to divide if it has reached the M phase.

D allow the cell to divide if it has reached the G1 phase.

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16 Refer to the following diagram, which shows a pair of homologous chromosomes before andduring a crossing-over event:

Which one of the following diagrams represents a structure that could not be formed after a single crossing-over event between the pair of chromosomes shown in the diagram above?

A B C D

17 Cancer cells divide out of control, forming tumours.

Which statement describes the difference between a cancer cell and a normal cell?

A Cancer cells do not undergo cytokinesis.

B Cancer cells have a shorter interphase.

C Cancer cells do not have metaphase.

D Only cancer cells have mutated DNA.

18 The table shows the percentages of nitrogenous bases in four samples of nucleic acids. Which base is adenine?

samplebases

A B C D uracil

1 19 31 30 19 nil

2 27 23 24 26 nil

3 25 25 nil 25 25

4 17 32 33 18 nil

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19 Erythromycin is an antibiotic that interferes with the process of protein synthesis in bacterial cells. It is possible that erythromycin would affect the

A transcription of mRNA in the nucleus of the bacterial cell.

B attachment of amino acids to mRNA.

C movement of ribosomes along mRNA.

D attachment of ribosomes to the endoplasmic reticulum of the bacterial cell.

20 An unidentified single- strand molecule was described as having the following features :

a complementary base pairing along some of its length an area that can attach to a ribosome a site to which a specific amino acid attaches

What is this unidentified molecule?

A DNA polymerase

B messenger RNA

C RNA polymerase

D transfer RNA

21 In a DNA molecule, the base sequence AGT codes for the amino acid serine. What is the base sequence for the anticodon on the tRNA to which serine becomes attached?

A AGU

B GAU

C TCA

D UCA

22 Which statements describe why a large animal has had to evolve a transport system?

1. diffusion occurs slowly over long distances2. it has a high rate of gas exchange3. it has a large surface area to volume ratio

A 1 only B 3 only C 1 and 2 only D 1, 2 and 3

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23 Each set of graphs represents data for blood vessels in the sequence:

art a c v vein

artery arterioles capillaries venules veins

Which set is correct?

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24 Which two statements about the Bohr effect are correct?

1 Increasing the partial pressure of oxygen increases the percentage of oxyhaemoglobin.2 Decreasing the partial pressure of carbon dioxide decreases the percentage of oxyhaemoglobin.3 Increasing the partial pressure of carbon dioxide shifts the dissociation curve of haemoglobin

to the left.4 In low concentrations of carbon dioxide haemoglobin has a high affinity for oxygen.

A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

25 When transpiration is at a maximum rate, tree trunks decrease in diameter.Which statement explains this?

A There is decreased suction pressure in the leaves.

B There is less adhesion between water and xylem vessel walls.

C There is less water in the xylem vessels.

D The water in the xylem vessels is under increased tension.

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26 A large number of aphids were used to collect samples of the contents of the sieve tubes of a tomato plant.

Different samples of the sieve tube solution were tested.

Which was the correct result?

Benedict’s testiodine in KI

before hydrolysis after hydrolysis

A blue red brown

B blue blue blue / black

C red blue blue / black

D red red brown

27 Which statement is an example of epidemiological evidence linking smoking to lung cancer?

A Chemical analysis of tar from cigarettes shows that it contains carcinogens.

B Dogs made to inhale the smoke from cigarettes develop lung tumors.

C The incidence of lung cancer in a population as more cigarettes are smoked.

D When tar from cigarettes is rubbed onto the skin of the mice, the mice develop skin tumors.

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28 The graph shows the volume of air breathed out quickly and with force, following a deep breath in, for three different people, X, Y and Z.

What is an explanation for the differences shown?

chronic bronchitis emphysema healthy lung function

A X Y Z

B X Z Y

C Y Z X

D Z Y X

29 What would be seen in an electron micrograph of a bronchus wall?

1. cartilage cells2. ciliated cells3. exocytotic vesicles

A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

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30 The disease smallpox has been eradicated by a worldwide vaccination programme.

Which set of reasons correctly identifies the problems associated with planning vaccination programmes to eradicate other diseases

TB malaria sickle cell anaemia

cholera

A

invade gut cells where immune

system less effective

genetically inherited recessive

condition

different vaccines needed for active and dormant-to-

active forms

poor response with malnourished children; boosters then required

B

different stages with different

antigens; invades body cells

poor response with malnourished

children; boosters then required

genetically inherited recessive

condition

different vaccines needed for active and dormant-to-

active forms

C

different vaccines needed for active and dormant-to-

active forms

different stages with different

antigens; invades body cells

genetically inherited recessive

condition

invade gut cells where immune system less

effective

Dgenetically

inherited recessive condition

different vaccines needed for active and dormant-to-

active forms

invade gut cells where immune

system less effective

different stages with different antigens; invades

body cells

31 Scientists are concerned that avian (bird) flu caused by the H5N1 virus, could infect humans and cause a pandemic.

If this occurs, which factors could help prevent humans spreading the disease?

1 killing all poultry 2 reducing all air flights

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3 taking a course of antibiotics

A 1 and 2 only B 2 only C 2 and 3 only D 1, 2 and 3

32 The following statements describe some of the stages in phagocytosis.

1. Bacteria become surrounded in a phagocytic vacuole.2. Bacteria release chemicals that attract neutrophils.3. Lysosomes fuse with the phagocytic vacuole.4. Receptor proteins on the neutrophil bind to the bacteria.

Which order defines the correct sequence for phagocytosis?

A 3 → 2 → 4 → 1

B 2 → 4 → 1 → 3

C 4 → 1 → 3 → 2

D 1 → 3 → 2 → 4

33 Some antibiotics are used in animal feed to reduce disease.What explains why these antibiotics should not be used in the treatment of human disease?

A humans may be allergic to these antibiotics

B human cells may stop responding to these antibiotics

C pathogenic bacteria may develop resistance to these antibiotics

D useful gut bacteria may be killed by these antibiotics

34 Where are antibodies and antigens found?

on surface of pathogen on surface of macrophage in blood plasma

A antibody antibody antigen

B antibody antigen antibody

C antigen antibody antigen

D antigen antigen antibody

35 Which description is correct for B-lymphocytes?

made from bone marrow stem cells

processed in the thymus release antibodies

A B

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C D

36 Why is passive immunity effective for only a short time?

A antibodies are rapidly broken down

B antigens are rapidly broken down

C memory cells soon die

D phagocytes soon die

37 What limits the number of trophic levels in a food chain?

A biomass of autotrophs

B efficiency of energy conversion between levels

C net productivity of ecosystem

D species diversity in ecosystem

38 The diagram shows an arctic ecosystem.

16

How many trophic levels are represented?

A 3 B 4 C 5 D 6

39 In an investigation, discs of 2.5 cm diameter were cut from leaves. Fifty discs were put into three identical bags with different net sizes and buried in newly dug soil at a depth of 3 cm.

At 60 day intervals the bags were dug up and the leaf discs measured to see how much of the leaf area had disappeared.

The table shows the percentage of leaf discs remaining in each bag.

percentage of leaf disks remaining

time / days net size 7 mm net size 0.5 mm net size 0.03 mm

0 100 100 100

60 80 94 100

120 30 81 100

180 14 67 100

240 9 63 100

300 6 61 100

Which organisms are most important for breaking down the leaves?

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A earthworms and beetles

B microorganisms only

C small invertebrates only

D small invertebrates and microorganisms

40 The diagram shows part of the nitrogen cycle.

Which process is increased in poorly drained soil?