10. Transport System in Organisms E-learning - Diffusion & Osmosis
Transcript of 10. Transport System in Organisms E-learning - Diffusion & Osmosis
Transport System in Organisms
1
Diffusion and Osmosis
2
Learning Outcomes for Section 1At the end of this lesson, you should be able to:
observe and infer that diffusion is the movement of molecules from a region of higher concentration
observe and infer that osmosis involves the movement of water molecules when two solutions of unequal concentration are separated by a partially permeable membrane
explain how diffusion and osmosis are involved in the transport system
explain the need for a transport system in multicellular organisms
3
Eww... What’s that smell???
4
How can we smell rubbish? Smell come from vapour from the
rubbish.Particles in the vapour move
about randomly.They bump into each other and
spread out quickly.Some of the particles enter our
nostrils.The spreading out of particles is
brought about by diffusion.
5
DiffusionDiffusion is the movement of particles from a region
of higher concentration to a region of lower concentration.
6
What is happening?
7
10.1 Diffusion and OsmosisFactors Affecting the Rate of Diffusion
Factor EffectTemperature ↑ Temperature, ↑ rate of diffusionMolecular Mass ↓ Molecular mass, ↑ rate of
diffusionThickness of barrier
↑ (Thicker) cell wall, ↓ rate of diffusion
Concentration gradient
↑ Concentration gradient, ↑ rate of diffusion
Surface-area-to- volume ratio
↑ Surface area-to-volume ratio, ↑ rate of diffusion
10.1 Diffusion and OsmosisSurface area-to- volume ratio
Cube Sides 1 cm Sides 2 cm Sides 3 cmSurface area/ cm2
6 x 1 x 1 = 6 6 x 2 x 2 = 24 6 x 3 x 3 = 54
Volume/ cm3
1 8 27
Surface area-to- volume ratio
6 : 1 24 :8= 3 :1
54 : 27= 2:1
Time/ s 1 3 10
The greater the ratio, the faster the rate of diffusion.
Diffusion through a Membrane
Diffusion can also occur through a membrane.
There are two types of membranes:Fully permeable membrane
Example: Cell wall of plant cellsPartially permeable membrane
Example: Cell membrane of cells
10
Diffusion through a Permeable Membrane
A fully permeable membrane allows all molecules to pass through it.
A partially permeable membrane allows only small molecules but not large molecules to pass through it.
11
Diffusion through a Partially Permeable MembraneA partially permeable membrane allows only small molecules
to pass through its pores but not the large ones.The small glucose molecules diffuse through the membrane
(Visking tubing) from inside the tube (higher glucose concentration) into the water (lower glucose concentration).
The starch molecules are too large to pass through the membrane.
12
Diffusion in Living Organisms1. Photosynthesis
Carbon dioxide diffuses from the air (higher carbon dioxide concentration) into the cells in the leaves (lower carbon dioxide concentration)
Oxygen produced diffuses from the cells in the leaves (higher oxygen concentration) into the air (lower oxygen concentration).
Gases exchange take place via the stomata.
Diffusion in Living Organisms2. The Human Body
In the human digestive system, digested food diffuses through the wall of the small intestine into the bloodstream.
Also, food and oxygen diffuse from the blood through the cell membranes into the body cells.
Osmosis When a piece of raisin is soaked in water, it swells
up and becomes less wrinkled.Water has diffused into the cells of the raisin through
the partially permeable membrane.
After soaking in
water for 1 h
Turgid (larger and firm)
Flaccid (smaller and soft)
15
OsmosisOsmosis is the net movement of water molecules
through a partially permeable membrane from a region with a higher concentration of water molecules to a region with a lower concentration of water molecules.
16
An Example of OsmosisA piece of potato is placed in distilled water.
After 20 minutes
After 20 minutes
original
Distilled water
An Example of OsmosisAfter 20 minutes of soaking in distilled water, the
potato pieces become larger, longer and firmer.
The water concentration of distilled water is higher than the water concentration of in the potato cells.
Therefore water molecules move via osmosis from the distilled water into the potato cells causing them to swell and become turgid.
Another Example of OsmosisWe can show osmosis using Visking tubing.
The pores in the Visking tubing allow the smaller water molecules but not the larger sugar molecules to pass through.
Another Example of Osmosis
The water concentration is _________ in the beaker than in the Visking tubing.
Therefore, water molecules move via _________ from the water in the beaker into the Visking tubing.
higher
osmosis
Another Example of Osmosis
This causes the water level in the glass tube to _______ and the water level in the beaker to _______.
risedrop
Osmosis in Living Organisms1. Roots
Water from the soil enters the root hair cells of a plant by osmosis.
This is because the water concentration in the soil is higher than in the cell solution of the root hair cells.
Osmosis in Living Organisms2. Stems and Leaves
Water moves into the cells of stems and leaves of a plant by osmosis.
This makes them firm and strong. Stems of non-woody plants need turgid cells to support
the plants. If this support is lost, the plant wilts.
24
Why is a transport system important to
multicellular organisms?
Diffusion and Osmosis in Unicellular OrganismsIn unicellular organisms, materials move into and out
of the cell directly by diffusion and osmosis. Hence, these organisms do not need a transport
system.
25
O2CO2
Is diffusion and osmosis efficient for multicellular organisms?In multicellular organisms, there are many cells. Most of
these cells are far away from the outside of the organism. Diffusion and osmosis alone are not fast or efficient
enough for the cells to get materials directly from the environment.
Hence, transport systems are needed to take substances to all the cells and to carry waste substances away.
26
Something Interesting
27
Checkpoint TimeDiffusion and osmosis are two common modes of movement for substances in living organisms.a) Give one example of diffusion taking place in living
organisms.
b) Give one example of osmosis taking place in living organisms.
28
Checkpoint TimeState whether each of the following statements about osmosis is true or false.
29
Statement True or
False
(a)Osmosis takes place when two solutions of different concentrations are separated by a partially permeable membrane.
(b)Osmosis can only take place in living tissues.
(c)Osmosis is the net movement of water molecules from a solution of lower concentration to a solution of higher water concentration through a partially permeable membrane.
Transport System in Plants
30
Learning Outcomes for Section 2At the end of this lesson, you should be able to:
describe briefly the process of absorption of water and mineral salts by the root of a plant
describe briefly the transport of water and manufactured food substances in the plant
explain the function of phloem and xylemuse terms such as translocation, transpiration pull,
active transport, diffusion and osmosis in the description of plants transport system
31
The Tallest Tree in the WorldThe giant redwood trees
in the USA.The trees are more than
a 100m tall.Everyday, the giant
redwood tree moves 1000kg of water from the soil to their leaves, 100m above the ground.
Is Osmosis sufficient?
Transport System in PlantsPlants need a transport
system to carry water, food and dissolved minerals to all cells in the plant.
The transport system is made up of vessels in the root, stem and leaves.
Vessels of the Plant Transport System
There are two types of vessels:
1. Xylem VesselsMade up of dead cells
and have thick wallsCarry water and
dissolved minerals from the roots to all parts of the plant.
Xylem vessels in the roots
Vessels of the Plant Transport System
2. Phloem VesselsMade up of living cells and have thin wallsCarry sugar produced in the leaves to other
parts of the plant.
Phloem vessels in the
roots
Vascular BundlesThe two vessels often run side by side forming
vascular bundles. Xylem vessels in
stem Phloem vessels in
stem
Vascular bundle
Observing vascular bundles in a celery stem
Xylem and Phloem in Different Parts of the Plants
38
1. Place a balsam plant in a container of dilute red ink for one day.
10.3 Transport System in Plants• Experiment 1: The path of water
through a plant
2. After one day, wash the roots under running tap water.
How is water
transported in a plant?
Transport tissue in plants
3. Observe the stem and leaves of the balsam plant. You will find that the red ink has risen in certain strands of the stem and veins of the leaf.
10.2 Transport System in Plants• Experiment 1: The path of water
through a plant
• The strands are vascular bundles which are part of the plant transport system.
• In the balsam plant, the vascular bundles are arranged in a ring within the stem.
• Each vascular bundle consists of xylem tissue and phloem tissue.
Which part of the vascular bundle was
actually stained red?
10.2 Transport System in Plants
The xylem tissue In Experiment 1, the xylem tissue was stained red. The xylem tissue consists of long tubes or vessels that pass from the roots to the leaves. Hence, the xylem tissue is able to transport water and mineral salts from the roots to the leaves.
xylem tissue phloem tissue
The phloem tissue The phloem tissue transports food (e.g. sugars) produced in the leaves to other parts of the plant.
10.3 Transport System in Plants• Experiment 2: How is food
transported in a plant?
1. Take the stem of a woody plant (e.g. hibiscus). Remove a ring of bark around the main stem. This should remove the phloem tissue, leaving the xylem tissue intact.
2. Water and mineral salts can still be transported in the plant.
10.3 Transport System in Plants3. After a few weeks, the part of
the stem just above the cut region will swell.
• Food cannot reach the roots because the phloem tissue is removed. It collects in the stem just above the cut, causing that area to swell.
• Without food (sucrose, amino acids), the roots will starve and die. The plant will eventually die as its roots cannot take in water from the soil.
What causes the swelling at this part?
vacuole
root hair cell
cytoplasm
cellulose cell wallcell
membrane
Absorption of Water and Mineral Salts by Roots
How are water and mineral
salts taken into a plant?
soil particlefilm of water
vacuole
root hair cell
cytoplasm
cellulose cell wall
cell membrane
soil particlefilm of water
Soil contains water and mineral salts. The root hair cells take in water by osmosis. The root hair cells also take in mineral salts by active transport, a process which requires energy.
Key:Movement of mineral saltsMovement of water molecules
lower concentration of water molecules
higher concentration of water molecules
Absorption of Water and Mineral Salts by Roots
Absorption of Water and Mineral Salts by RootsKey:
Movement of mineral saltsMovement of water molecules
vacuole
root hair cell
cytoplasm
cellulose cell wallcell membrane
soil particlefilm of water
lower concentration of water molecules
higher concentration of water molecules
After the water and mineral salts are taken in, the water molecules move from one cell to the next by osmosis.
The mineral salts move from one cell to the next by diffusion.
The water and mineral salts will continue to move from one cell to the next until they reach the stem.
How does this
process allow
plants in
hydroponic
systems to
survive?
Transport of Water and Mineral Salts (Xylem)
Water and mineral salts move up the plant mainly by transpiration pull and in some plants, by root pressure.
Transpiration pullThis pulling force is produced
when water evaporates from the leaves through the stomata.
This force is similar to someone sucking up liquid through a straw.
A pretty blue rose from a plain white one.
Transport of Food (Phloem)During photosynthesis, food is produced in the leaves in the form of sugar (glucose) which is then transported to other parts of the plant via the phloem.There is a higher sugar concentration in the leaf than in the phloem vessels which are constantly transporting sugar to other parts of the plant.
Therefore diffusion occurs to transport sugar from the leaves to phloem vessels.
The movement of glucose in the phloem occurs in both directions.
Transport of Food (Phloem)
Exchanges of Gases during Photosynthesis
Carbon dioxide is needed for photosynthesis. There is a higher concentration of carbon dioxide in the surroundings than in the leaf. Therefore, carbon dioxide diffuses from the surroundings to the leaf.
Oxygen is produced during photosynthesis. There is a higher concentration of oxygen in the leaf than in the surroundings. Therefore, oxygen diffuses from the leaf to the surroundings.
51
Transport System in a Flowering Plant
1. Water enters a plant through its roots by osmosis. Dissolved minerals are absorbed through diffusion and active transport.
2. Water and minerals move up the stem through xylem vessels.
3. Xylem vessels carry water and dissolved minerals from the roots to the leaves.
4. Most of the water evaporates and diffuses from the leaves through transpiration.
7. Oxygen diffuses from the leaves to the surroundings.
8. Sugar moves from the leaves through phloem vessels to the rest of the plants.
52
Movement of waterMovement of sugarMovement of carbon dioxideMovement of oxygen
5. Carbon dioxide diffuses from the surrounding to the leaves.
6. Carbon dioxide and some water are used during photosynthesis by the leaves to produce sugar and oxygen.
Checkpoint TimeComplete the following sentences.1. Water molecules that are taken into a plant move
from one cell to another by ________________.2. Plants can obtain ______________ and
________________________ from soil.3. Mineral salts that are taken into a plant move from
one cell to another by __________________.
53
Checkpoint TimeThe figure below shows a cross section of the stem of a green plant.
a) Identify the parts labelled 1 and 2.1: _____________________2: _____________________
54
Checkpoint Timeb) Name the substances transported by the parts
labelled 1 and 2.1: ______________________________________2: ______________________________________
55
Transport System in Humans
56
Learning Outcomes for Section 3At the end of this lesson, you should be able to:
describe and explain the functions of the 3 main transport system in humans i.e. the heart, the blood vessels and the blood
understand parts of the heart and the double circulation system involved
understand the function of arteries, veins and capillaries and briefly describe areas where they are found
briefly describe different parts of the blood and how blood acts as a transport medium
57
Transport System in HumanCirculatory system is the main
transport system in the human body.
It consists of three parts:1. Heart – an organ which pumps
blood around the body2. Blood – a liquid which
transport materials3. Blood vessels – network of
tubes which carry blood round the body
58
Transport System in Human1. Heart
Its purpose is to pump blood round the body.
The heart has 4 chambers. Two upper chambers called the
right atrium and left atrium (plural: atria)
Two lower chambers called the right ventricle and left ventricle (plural: ventricles)
The wall down the middle of the heart that separates the left side from the right side is called the septum.
59
Transport System in Human1. Heart
The valves in the heart open and close to ensure that blood flows only in one direction.
60
Section of a Mammalian Heart
61
Artery
Septum
Vein
Right atrium
Valve.
Valve
Right ventricle
Artery
Vein
Left atrium
Valve.
Valve
Septum
Left ventricle
Transport System in Human2. Blood
The human body has about 5 litres of blood. Blood has 2 functions:
To transport materials (e.g. nutrients, oxygen, carbon dioxide and other waste substances) round the body
To protect us against diseases Blood contains:
a. red blood cellsb. white blood cellsc. plateletsd. plasma
62
Transport System in Human2. Blood
Red blood cells Red blood cells are biconcave in shape to
increase its surface-area-to-volume ratio for oxygen absorption.
Red blood cells have no nuclei so as to pack in more oxygen.
Red blood cells contain haemoglobin, which combines with oxygen and carries it round the body
The haemoglobin then releases oxygen as it passes the cells. This oxygen is used by the cells for respiration.
The red blood cells then collect carbon dioxide (a waste product of respiration) by diffusion.
The red blood cells are bright red when they carry oxygen.63
Transport System in Human2. Blood
Red blood cells When oxygen is bound to
haemoglobin, blood appears to be bright red.
At the cells where oxygen is needed for respiration, haemoglobin will release the oxygen molecules it is carrying.
When oxygen is released from haemoglobin, blood appears to be dark red.
The red blood cells then collect carbon dioxide (a waste product of respiration) by diffusion.
64
Transport System in Human2. Blood
White blood cells There are fewer white blood cells than red blood cells. They are colourless and are larger than red blood cells
and have nuclei. Some white blood cells are used to fight infections. They produce antibodies to kill bacteria Alternatively, they engulf and digest bacteria.
65
Transport System in Human2. Blood
White blood cells
66
Transport System in Human2. Blood
Platelets These are tiny pieces of blood cells. They help blood to clot when we bleed.
Platelet
67
Transport System in Human2. Blood
Plasma Plasma is a pale yellow liquid made up of 95% water with
dissolved substances including nutrients (glucose, amino acids, fatty acids, mineral salts) and waste substances.
It transports digested food, waste materials (e.g. carbon dioxide and urea) and other materials (e.g. hormones and mineral salts).
68
Transport System in Human3. Blood Vessels
Blood vessel is a network of tubes carrying blood around our body, from the heart to the rest of our body, and then back to the heart.
There are three types of blood vessels: arteries, veins and capillaries.
69
3. Blood VesselsTransport System in Human
Artery Vein CapillaryFunction Carry oxygenated blood
away from the heart to all other parts of the bodyExcept pulmonary artery
Carry deoxygenated blood from the rest of the body back to the heartExcept pulmonary vein
Connect arteries to veinsCarry blood to all cellsAllow exchange of nutrients, gases and wastes
Pressure Under high pressure Under low pressure -
Thickness of walls
Have thick, elastic muscular walls
Have very thin walls Have walls which are one-cell thick (to ensure fast diffusion of substances)
Presence of valves
No Yes (To prevent the backflow of blood)
No
Diagram
70
Transport System in Humans
right
lung
Key:Deoxygenated bloodOxygenated blood brain
other parts of the body
left lung
VeinsVeins carry blood towards the heart.
heart
right
lung
Key:Deoxygenated bloodOxygenated blood brain
other parts of the body
left lung
The arteriesThe arteries carry blood away from the heart.
The heartThe heart is a muscular pump. Its pumping action keeps the blood circulating around the body quickly and continuously.
heart
Transport System in Humans
n Humans
right
lung
Key:Deoxygenated bloodOxygenated blood brain
other parts of the body
left lung
The capillaries These are very tiny blood vessels that connect the arteries to the veins. The capillary walls are one-cell thick. This allows quick diffusion of nutrients and oxygen from the blood to the tissue cells. The capillaries Waste substances such as carbon dioxide can also move from the tissue cells into the blood in the capillaries.
BloodBlood is continuously circulated around the body, transporting many substances. Blood also protects the body from disease-causing germs.
BloodIn places with low oxygen, our body produces more red blood cells to transport more oxygen.
heart
Transport System in Humans
Transport System in Human
74
Transport System in HumanExplain why the left ventricle has a thicker muscular
wall than the right ventricle.
75
The left ventricle must pump blood at high pressure so that blood can travel to the rest of the body.
Double Circulation in HumanThe double circulatory system of blood flow occurs when
the blood enters the heart twice.All animals with lungs have a double circulatory system.
The cycle is heart body heart lungs heartIn contrast, fish have a single circulation system because
they do not have lungs. The cycle is heart gills body heart
76
Double Circulation in HumanDouble circulation is much more efficient than single
circulation. In a fish blood pressure goes down as is passes through capillaries in gills so it is slower and takes longer for oxygen and nutrients to get around the body.
In humans the blood pressure can be increased after it has left the lungs. It is faster. Humans are more active than fish and need to produce more energy and heat.
77
Respiratory System: LungsIn the lungs, blood picks up oxygen and loses
carbon dioxide.
The air we breathe contains high concentration of oxygen and low concentration of carbon dioxide.
Lung
The blood flowing towards the lungs contains low concentration of oxygen and high concentration of carbon dioxide.
Therefore, oxygen from the lungs will diffuse into the blood and carbon dioxide from the blood will diffuse into the lungs.
Respiratory System: Lungs
Lung
Our Respiratory System
Digestive SystemIn the small intestine,
blood picks up small, digested food molecules such as glucose, amino acids and fatty acids.
As the blood flows around the body, it will distribute these food molecules to the cells that need them.
Oesophagus
Checkpoint TimeIdentify the components of the human circulatory
system.
82
Checkpoint TimeThe diagram below shows a vertical section of the heart in humans.
Label A, B, C and D.A: __________________ B: ___________________ C: __________________ D: ___________________ 83
Checkpoint TimeThe diagram below shows a vertical section of the heart in humans.
In which labelled structure does blood reach the maximum pressure?
84