Section 8 - Exchange and Transport in Animals

Question 1

Give waste products that need to be removed from cells.

Answer 1

carbon dioxide and urea

Question 2

Give four substances that cells need to take in from the environment.

Answer 2

oxygen, water, dissolved food molecules and mineral ions.

Question 3

Outline how aerobic respiration drives the need for the transport of gases in and out of cells.

Answer 3

Aerobic respiration requires oxygen to be taken into cells. Aerobic respiration produces carbon dioxide that needs to be removed from the cells.

Question 4

What is alveoli?

Answer 4

alveoli are small air sacs in the lungs where gas exchange takes place

Question 5

Explain why alveoli need a good blood supply for efficient gas exchange.

Answer 5

To maintain the concentration gradients of oxygen and carbon dioxide.

Question 6

Explain how gas is exchanged between the lungs and blood that has just returned from the rest of the body.

Answer 6

The alveoli are surrounded by capillaries carrying blood that has just returned from the rest of the body. The blood contains lots of carbon dioxide and not much oxygen. In alveoli, the oxygen concentration is high and the carbon dioxide concentration is low. This means oxygen diffuses out of the alveoli into the blood, and carbon dioxide diffuses out of the blood into the alveoli.

Question 7

What other name can be used for erythrocytes?

Answer 7

red blood cells

Question 8

What is the function of white blood cells?

Answer 8

they defend the body against infection

Question 9

What is plasma?

Answer 9

the liquid that carries everything in blood.

Question 10

Describe the function of lymphocytes.

Answer 10

white blood cells that produce antibodies against microorganisms. Some also produce antitoxins to neutralise any toxins produced by the microorganisms

Question 11

Explain the importance of haemoglobin in red blood cells.

Answer 11

Haemoglobin enables red blood cells to carry oxygen through the body. In the lungs, haemoglobin binds to oxygen to become oxyhaemoglobin. In body tissues, oxyhaemoglobin splits up to release oxygen to the cells.

Question 12

True or false? Arteries carry blood to the heart.

Answer 12

False. Arteries carry the blood away from the heart. Veins carry blood to the heart.

Question 13

Which type of blood vessel has the largest lumen?

Answer 13

veins

Question 14

Which type of vessel contains valves? What is their function?

Answer 14

Veins have valves. They help to keep the blood flowing in the right direction.

Question 15

What is the disadvantage of the walls of capillaries being only one cell thick?

Answer 15

It means the distance over which materials are exchanged is very small, so the rate of diffusion between capillaries and cells is high.

Question 16

Describe the difference in thickness between an artery wall and a vein wall. Why does this difference exist?

Answer 16

Arteries have thicker walls than veins. Arteries carry blood that has been pumped from the heart at high pressure, so the walls have thick layers of muscle and elastic fibres to make them strong and elastic. In veins, blood is at a lower pressure, so the walls don’t need to be as thick.

Question 17

Capillaries branch out to form a network of blood vessels, rather than continuing as a single blood vessel. Suggest why.

Answer 17

Capillaries branch out, allowing them to get close to every cell in the body in order to exchange substances with them.

Question 18

Which side of the heart pumps deoxygenated blood to the lungs?

Answer 18

Right side

Question 19

Name the blood vessel which carries blood into the right atrium of the heart.

Answer 19

vena cava

Question 20

What is meant by cardiac output?

Answer 20

The total volume of blood pumped by a ventricle every minute.

Question 21

What is the function of valves in the heart.

Answer 21

Valves stop the blood from flowing backwards.

Question 22

Describe the route that blood from the lungs take through the heart.

Answer 22

Oxygenated blood from the lungs enters the atrium through the pulmonary vein. It then moves through to the left ventricle, and then leaves the heart via the aorta.

Question 23

Where in the body does respiration take place?

Answer 23

Occurs in every cell in the body.

Question 24

Give the product(s) of anaerobic respiration in plant cells.

Answer 24

ethanol and carbon dioxide

Question 25

Give one factor that could affect the rate of respiration in an organism

Answer 25

temperature

Question 26

Why would you put soda lime in a respirometer?

Answer 26

Soda lime would absorb any CO₂ produced so that it won’t affect the results.