Topic 8- Exchange and transport in animals

Question 1

What are the three factors affecting the rate of diffusion?

Answer 1

Concentration gradient

Diffusion distance

Surface area

Question 2

How are the alveoli adapted for gas exchange?

Answer 2

Large surface area

Many millions of alveoli in the lungs

Thin cell wall - one cell thick

Moist lining for dissolving gases

A good blood supply to maintain the concentration gradients of O2 and CO2

Question 3

What are the adaptations of red blood cells (erethrocytes)?

Answer 3

Biconcave disc shape for large surface area: volume ratio for absorbing oxygen

No nucleus for more room to carry oxygen

Haemoglobin (containing iron) which binds to oxygen to form oxyhaemoglobin

Question 4

What is the function and the adaptions of phagocytes?

Answer 4

They change shape to engulf unwanted microorganisms

Question 5

What is the function and adaptations of lymphocytes?

Answer 5

They produce antibodies which bind to foreign cells and destroy the cells.

Some lymphocytes also produce antitoxins to neutralise any toxins produced by the microorganisms

Question 6

What is the function of platelets?

Answer 6

They are small fragments of cells with no nucleus that help the blood to clot into a wound. This stops all of your blood from pouring out and to stop microorganisms to get in.

Question 7

What is the function of plasma?

Answer 7

Pale straw coloured liquid that carries almost everything, such as:

Red and white blood cells and platelets

Nutrients like glucose and amino acids. These are the soluble products of digestion which are absorbed from the gut and taken to the cells of the body

Carbon dioxide from the organs to the lungs

Urea from the liver to the kidney

Hormones

Proteins

Antibodies and antitoxins produced by white blood cells

Question 8

What is the function of arteries?

Answer 8

They carry blood away from the heart

Question 9

What is the function of capillaries?

Answer 9

They are involved in the exchange of materials at the tissues

Question 10

What is the function of the veins?

Answer 10

They carry the blood to the heart

Question 11

What are the properties of arteries?

Answer 11

The heart pumps the blood out at high pressure so the artery walls are strong and elastic

Thick walls compared to the size of the lumen to withstand pressure

Smaller lumen size to maintain pressure

They contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back

Question 12

What are the properties of capillaries?

Answer 12

Very narrow, so they can squeeze into the gaps between cells. This means they can carry the blood really close to every cell in the body to exchange substances with them

They supply food and oxygen, and take away CO2

Thin cell wall - one cell thick. This increases the rate of diffusion by decreasing the distance over which it occure

Permeable walls, so substances can diffuse in and out

Question 13

What are the properties of veins?

Answer 13

Capillaries join up to form veins

The blood is at lower pressure in the veins so the walls don’t need to be as thick as artery walls

Bigger lumen than arteries to help blood flow, despite their lower pressure

Valves to keep blood flowing in the right direction

Question 14

What is respiration?

Answer 14

The process of transferring energy from the breakdown of organic compounds (such as glucose)

Question 15

What is the word equation for aerobic respiration?

Answer 15

glucose + oxygen —-> carbon dioxide + water

Question 16

What is the word equation for anaerobic respiration?

Answer 16

glucose —> lactic acid

Question 17

What is the word equation for anaerobic respiration in plants?

Answer 17

glucose —> ethanol + carbon dioxide

Question 18

Give three reasons as to why organisms exchange substances with their environment?

Answer 18

• Oxygen for aerobic respiration
• Water- taken up by cells by osmosis
• Removal of urea, urea diffuses from cells to the blood plasma

Question 19

Why do multicellular organisms need exchange surfaces?

Answer 19

Because they have a smaller surface area compared to their volume.

This makes it difficult to exchange enough substances to supply their entire volume across their outside surface alone.

So they need some sort of exchange surface for efficient diffusion and a mass transport system to move substances between the exchange surface and the rest of their body

Question 19

Why do single cells organisms not require exchange surfaces?

Answer 19

Because gases and dissolved substance can diffuse directly into the cell across the cell membrane because they have a large surface area to volume ratio

Question 20

What is the role of the lungs?

Answer 20

To transfer oxygen into the blood and remove waste carbon dioxide from it

Question 21

Where are the alveoli found and what are they?

Answer 21

They are little air sacs found in the lungs

Question 22

Describe the stages of gas exchange between alveoli and the blood?

Answer 22

Blood arriving at the alveoli has just returned to the lungs from the rest of the body, so it contains lots of CO2 and not much O2. This maximises the concentration gradient for the diffusion of both gases.

O2 diffuses out of the air in the alveoli (where the concentration of O2 is high) and into the blood (where the concentration of O2 is low)

CO2 diffuses in the opposite direction to be breathed out

Question 23

What is fick’s law?

Answer 23

Rate of diffusion is directly proportional to:

SA X Concentration difference/thickness of membrane

Question 24

According to Fick's law, when the surface area doubles, what happens to the thickness of the membrane?

Answer 24

It halves

Question 25

What is the role of red blood cells (erythrocytes)?

Answer 25

To carry oxygen from the lungs to all the cells in the body

Question 26

What does oxyhaemoglobin split up to form in body tissues?

Answer 26

Haemoglobin and oxygen, to release oxygen into the cells

Question 27

What do haemoglobin and oxygen bind to form in the lungs?

Answer 27

oxyhaemoglobin

Question 28

What is the process known as in which phagocytes engulf unwanted microorganisms?

Answer 28

phagocytosis

Question 29

What happens when there is a lack of platelets?

Answer 29

Excessive bleeding and bruisins

Question 30

Briefly explain how a double circulatory system works in mammals

Answer 30

The heart pumps blood around the body in two circuits. In the first circuit, the heart pumps deoxygenated blood to the lungs to take in oxygen. In the second circuit, the hear pumps Oxygenated blood around all the other organs of the body to deliver oxygen to the body cells. Deoxygenated blood then returns to the heart

Question 31

How does a single circulatory system work in fish?

Answer 31

Deoxygenated blood from the fish's body travels to the heart, which then pumps it right round the body again in a single circuit.

Question 32

Describe how blood is pumped throughout the body

Answer 32

The right atrium of the heart receives deoxygenated blood from the body through the vena cava. The deoxygenated blood moves through to the right ventricle, which pumps it to the lungs via the pulmonary artery. The left atrium receives oxygenated blood from the lungs through the pulmonary vein The oxygenated blood then moves to the left ventricle, which pumps it out round the whole body via the aorta

Question 33

Why does the left ventricle have a much thicker wall than the right ventricle?

Answer 33

Because is needs more muscle because it has to pump blood around the whole body at high pressure, whereas the right ventricle only has to pump it to the lungs

Question 34

What are the functions of valves?

Answer 34

To prevent the backflow of blood in the heart

Question 35

What is the equation for cardiac output?

Answer 35

Cardiac output (cm3 min-1) = heart rate (b/m X stroke volume (cm3)

Question 36

Give three examples of what the energy from respiration is used for in mammals?

Answer 36

Metabolic processes Contracting muscles Maintaining a steady body temperature

Question 37

Why is anaerobic respiration used?

Answer 37

When you do vigorous exercise your body can't supply enough oxygen to your muscles for aerobic respiration- even though your heart rate and breathing rate increase. This means that your muscles have to start respiring anaerobically

Question 38

What does the build up of lactic acid cause?

Answer 38

Cramps

Question 39

How can you measure the rate of respiration?

Answer 39

1) Add some soda lime granules to two test tubes. Soda lime absorbs the CO2 produced 2) A ball of cotton wool is placed above the soda lime in each tube. Woodlice are placed on top of the cotton wool in each tube. Glass beads with the same mass as the woodlice are used in the control tube instead of woodlice 3) The respirometer is then set up going into both test tubes 4) The syringe is used to set the fluid in the manometer to a known level 5)The apparatus is then left for a set period of time in a water bath set to 15C 6) During this time, there'll be a decrease in the volume of the air in the test tube containing the woodlice. This is because the woodlice use up oxygen in the tube as they respire. (The CO2 they produce is absorbed by the soda lime so it doesn't affect the experiment) 7) The decrease in volume reduced the pressure in the tube, causing the coloured liquid in the manometer to move towards the test tube containing the woodlice 8) The distance moved by the liquid in a given time is measured. This value can then be used to calculate the volume of oxygen taken in by the woodlice per minute. This gives you the rate of respiration 9) Repeat steps 1-8 with the water bath set at different temperatures. This will allow you to see how changing the temperature affects the rate of respiration