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Transport and Circulation

IGCSE Section 2: Structures and functions in living organisms: TRANSPORT (Covering points 2.49-2.66)


on 5 December 2016

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Transcript of Transport and Circulation

IGCSE Section 2: Structures and functions in living organisms
(Covering points 2.49 - 2.66)

Transport and Circulation
2.49 understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cell
2.50 understand the need for a transport system in mulitcellular organisms
Why do multicellular organisms need a complex transport system within them?
3 min in the back of your books, work in pairs and jot down some ideas.
How does an amoeba get all the nutrients and other molecules it needs to survive?
when an organism is small enough, diffusion allows it to get all the essential molecules it needs.

organisms that are larger than this cannot, as they have many more cells that have the same requirements.

Their environments do not allow rapid diffusion of these molecules.
1. know about how unicellular organisms acquire nutrients
2. Understand why multicellular organsisms have a complex transport system.

1. Know adaptations, structure and functions of a root hair cell.
2. Learn about xylem and phloem
3. understand the differences between xylem and phloem in terms of tissue, structure and function
2.51 Describe the role of the phloem in transporting sucrose and amino acids between the leaves and other parts of the plants
2.52 Describe the role of the xylem in transporting water and mineral salts from the roots to other parts of the plants.
2.53 explain how water is absorbed by root hair cells.
Root hair cells
What is the point of a plant having roots?
To keep the organism anchored
To absorb water
To absorb minerals
How does it do it?
What are the adaptations of root hair cells?
Increased surface area available for absorption
No chloroplasts. They are underground so will not get any sunlight.
How does an oak tree get water from its roots, all the way to its top??
So its like a giant straw then...?
What causes the water to rise?
Transpiration and photosynthesis in leaves causes the water potential in leaf cells to drop. This then allows water to move from areas of high water potential into the leaf cells.

This allows water to move around the plant, supplying cells with water for photosynthesis and for structural turgidity, and other cells with minerals dissolved in the water.
Xylem and Phloem
How do root hair cells get water into the plant?
If this is the answer then what is the question?
True or False?
1. Osmosis is the net movement of water molecules from an area of low water potential to an area of high water potential, following a water potential gradient through an impermeable membrane.

2. The plant actively transports water up from the soil through its roots.

3. Magnesium is needed to create chlorophyll.

4. Phloem is dead, lignified cells arranged end to end.
1. Xylem not phloem

2. Transpiration stream

3. Osmosis

4. Water potential
Xylem is made of dead cells arranged end to end.

They grow like normal cells and eventually die to form tubes.
Their cell walls contain LIGNIN-a woody substance that gives strength and is impermeable.
Phloem is living tissue
Sieve plates allow the connection of cytoplasm between cells forming a sieve tube.

The sieve tube transports glucose, sucrose and amino acids around the plant.

Sieve cells have no nucleus, but their companion cell help to control them.
2.54 recall that transpiration is the evaporation of water from the surface of a plant

2.55 explain how the rate of transpiration is affected by changes in humidity, wind speed, temperature and light intensity.

2.56 describe experiments to investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot.
Look at vascular tissue through a microscope and identify the two key types of tissue.

Know how different factors can affect the rate of transpiration in a plant and how this can be measured.
In the back of your books...
What is transpiration?
How does water potential cause osmosis?

What two things can lower the water potential in leaves?

What are the adaptations of a root hair cell?
Get a microscope each and start looking at some slides of leaf vasculature.

Stick in the diagram

Draw a small section of vasculature from a slide of your choice.
2.57 recall the composition of the blood: red blood cells, white blood cells, platelets and plasma
2.58 understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energy
2.59 describe the adaptations of red blood cells, including shape, structure and the presence of haemoglobin
Know the composition of the blood
Learn and understand the role of plasma
Learn about red blood cells and be able to describe their adaptations
In the back of your books...
What makes up our blood?

How much of our blood does each constituent make up?
Other essential molecules (Proteins, glucose, hormones and blood clotting factors) are also transported in the blood.
Plasma makes up roughly
55% of your blood volume and is mostly water
It is the main transport medium for excretory products. These include: Carbon Dioxide and Urea.
(This is how the majority of Carbon Dioxide is transported in the blood)
What is the job of a red blood cell?

What adaptations do they have which make them good at this job?
In pairs in the back of your books, try and answer these questions
No Nucleus: RBCs have no nucleus. This means that there is more room inside a cell for the protein Haemoglobin, which reversibly binds with oxygen.
Biconcave shape: The shape of the RBC increases its surface area to volume ratio in order to increase the speed of gaseous diffusion
Haemoglobin: RBCs are packed with this protein. It is responsible for carrying oxygen molecules around the body. Each RBC contains 270 million of these molecules
Average humans have 3x10E13 RBCs in their body.

One molecule of Haemoglobin can carry 4 Oxygen molecules.

How many RBCs are in the average human?

What are the adaptations of red blood cells?

What is the role of blood plasma?

What % of the blood does the buffy coat comprise?
Research the drug EPO (erythropoietin).
Discuss its therapeutic roles.
Discuss how and why it was used as a performance enhancing drug in sport (cycling).
2.60 describe how the immune system responds to disease by using white blood cells, illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies specific to the pathogen

2.61 understand that vaccination results in the manufacture of memory cells, which enable to future antibody production to the pathogen to occur sooner, faster and in greater quantity

2.62 recall that platelets are involved in blood clotting, which prevents blood loss and the entry of microorganisms
Know how white blood cells work to protect the body from disease.
Learn and understand how vaccination allows the body to respond to diseases.
Know how platelets help to repair and protect the body from disease.
What is the immune system and why do we need it?
In pairs in the back of your book (2 mins)
Ans: To protect the body from disease
How does it do this?
It must kill bacterial cells, and viral molecules, but not attack the organism’s own healthy tissue.
An antigen is a marker molecule that can be found on the surface of all cells and viruses.

When foreign antigens are detected by Leukocytes (White blood cells) they produce antibodies which are specific to that antigen.

Antibodies are proteins that travel in the blood plasma.
Leukocytes (WBCs)
There are two major classes of Leukocytes
Manufacture ANTIBODIES

ANTIBODIES attach to ANTIGENS and can have 3 functions

1.Stick to antigens on bacteria and cause them to burst
2.Label and group bacteria for PHAGOCYTES
3.Neutralise toxins
Some Lymphocytes become MEMORY CELLS, and are involved in immunity.
Phagocytes surround bacteria with PSEUDOPODIA, and enclose them in a vesicle where they destroy them with enzymes.
Using page 61, draw a step by step diagram of phagocytosis by a WBC
After lymphocytes have produced antibodies, some of their population become MEMORY CELLS.

Upon a second exposure, they recognise the antigen to which they were first activated against and can produce antibodies at a much faster rate.
Draw a graph to show the primary immune and secondary immune responses using these axis:
In the back of your books...
Immunity can be natural or artificial.

How do you think that a person could be given immunity and what effect would that have?
How it’s done:
A weakened strain of the organism is administered
Harmless bacteria that carry pathogenic antigens
Just the antigens are administered
Modified toxins are used (e.g. Tetanus)
‘dead’ organisms are used
Blood Clotting
If we get a cut pathogens could enter our body. To protect us we plug the hole with a BLOOD CLOT.

Platelets are involved in clotting.

When exposed to air they release a chemical.

Traveling in the blood is FIBRINOGEN, a soluble protein.

When platelets release their chemical it causes FIBRINOGEN to form an
insoluble protein called FIBRIN.

This traps blood cells and makes a clot.
Draw a cartoon of how Platelets are involved in blood clotting.
2.63 describe the structure of the heart and how it functions

2.64 understand that the heart rate changes during exercise and under the influence of

2.65 describe the structure of arteries, veins and capillaries and understand their roles

2.66 recall the general plan of the circulation system to include the blood vessels to and from
the heart, the lungs, the liver and the kidneys.
Know the structure of the heart and how it functions
Learn about heart rate and know how and when it can change
Know the composition and function of the circulatory system
The heart pumps blood around the body.

The heart pumps blood to the lungs to collect oxygen and release carbon dioxide.

The heart pumps blood full of oxygen around the body.
On scrap paper, draw what you think the inside of the heart looks like.

Use the statements and diagrams just discussed and looked at to help.
By Mr Jolly
Using the diagram and what we have just discussed, complete the statement sort on how the heart beats.
Control of heart rate
What is the average resting heartbeat?
Why does this sometimes change?
Blood supply to the heart.
The heart is a muscle and like any muscle it needs oxygen to respire. It has its own network of arteries and veins called CORONARY/CARDIAC arteries and veins.
Two main ways:

Adrenaline: a hormone released from the adrenal glands. Causes fight or flight or freeze responses. Increases heart rate.
Increased CO2 concentration in the blood. This is detected by the MEDULLA in the brain which acts on the heart.
Blood vessels.
What is the difference between arteries and veins?
Ans: Arteries carry blood away from the heart
Veins carry blood back to the heart.
Why do these two types of vessels have different structures?
Veins carry blood at low pressures. They have valves in them to ensure that blood always travels back towards the heart.
What are capillaries and why do they need to be different?
These vessels deliver blood to organs.
They have thin walls to allow molecules to move into and out of the blood quickly.
In the back of your books:
1. Arteries have larger lumen than veins.
2. The medulla controls heart rate by detecting CO2 levels in the blood.
3. Adrenaline slows down the heart rate.
4. Valves are in arteries to increase pressure.
5. Humans have a double circulatory system.
If this is the answer then what is the question?
1. Lower pressure.
2. To stop blood from flowing the wrong way.
3. To increase ability for molecules to move into and out of the blood.
Vaccinations create memory cells

1/2 a page to a page of research covering these points:

What is it?
How does it work?
What considerations are necessary?
How will it affect the recipient?
Will the recipient have to take any medication and, if so, why?

On your own, describe and explain how these four factors can affect the rate of transpiration:
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