Diffusion, gas exchange and respiration

Question 1

Which substances do humans need to take in?

Answer 1

Oxygen, glucose, water, mineral ions, dissolved food molecules

Question 2

Which substances do humans need to remove?

Answer 2

carbon dioxide, urea, excess mineral ions, excess water

Question 3

What is the site of gas exchange in humans?

Answer 3

alveoli

Question 4

How does surface area affect rate of diffusion?

Answer 4

larger surface area to volume ratio = faster diffusion

Question 5

What is a concentration gradient?

Answer 5

Difference in concentration between two areas

Question 6

How does concentration gradient affect rate of diffusion?

Answer 6

Larger/steeper concentration gradient = faster diffusion

Question 7

How does diffusion distance affect rate of diffusion?

Answer 7

Further distance / thicker membrane = faster diffusion

Question 8

How does temperature affect rate of diffusion?

Answer 8

Higher temperature = faster diffusion

Question 9

Why does temperature affect rate of diffusion?

Answer 9

At higher temperatures molecules gain energy so move faster, speeding up diffusion

Question 10

What is diffusion?

Answer 10

Movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient

Question 11

Name 3 features of alveoli which make them suitable for gas exchange

Answer 11

thin walls, good blood supply, large surface area:volume ratio

Question 12

What is the word equation for aerobic respiration?

Answer 12

glucose + oxygen -> carbon dioxide + water

Question 13

What is the word equation for anaerobic respiration?

Answer 13

Glucose -> lactic acid

Question 14

What is the purpose of respiration?

Answer 14

To produce energy for life processes

Question 15

When is anaerobic respiration used?

Answer 15

When the body cannot supply enough oxygen to cells, e.g. during intense exercise

Question 16

Which produces more energy; anaerobic or aerobic respiration?

Answer 16

Aerobic

Question 17

What is the problem with producing lactic acid?

Answer 17

Lactic acid is toxic and corrosive to cells. When it builds up it damages tissues

Question 18

Where does respiration take place?

Answer 18

Mitochondria of all cells

Question 19

Is respiration endothermic or exothermic?

Answer 19

exothermic

Question 20

Which piece of equipment measures rate of respiration?

Answer 20

respirometer

Question 21

How can we measure rate of respiration?

Answer 21

by measuring the amount of oxygen used or carbon dioxide produced in a given time