b3

Question 1

Name the five levels of organisation.

Answer 1

cells→tissues→organs→organ systems→organisms

Question 2

What is a tissue?

Answer 2

group of cells with similar structures and functions

Question 3

What is an organ?

Answer 3

group of tissues working together to perform a specific function

Question 4

What is the function of the liver in digestion?

Answer 4

produces bile, which neutralises hydrochloric acid from the stomach and emulsifies fat to form small droplets with a large surface area

Question 5

What is the function of saliva in digestion?

Answer 5

lubrication to help swallowing - contains amylase to break down starch

Question 6

Name three enzymes produced in the pancreas?

Answer 6

amylase, protease, lipase

Question 7

What are enzymes?

Answer 7

protein molecules that catalyse specific reactions in organisms

Question 8

Why are enzymes described as specific?

Answer 8

each enzyme only catalyses a specific reaction, because the active site only fits together with certain substances (like a lock and key)

Question 9

Describe the function of amylase.

Answer 9

to break down starch into glucose

Question 10

Where is amylase produced?

Answer 10

salivary glands, pancreas, and small intestine

Question 11

Describe the function of proteases.

Answer 11

to break down proteins into amino acids

Question 12

Where are proteases produced?

Answer 12

stomach, pancreas, and small intestine

Question 13

Describe the function of lipases.

Answer 13

to break down lipids into fatty acids and glycerol

Question 14

Where are lipases produced?

Answer 14

pancreas and small intestine

Question 15

What are two factors that affect the rate of activity of an enzyme?

Answer 15

temperature and pH

Question 16

What does denatured mean?

Answer 16

shape of an enzyme’s active site is changed by high
temperatures or an extreme pH, so it can no longer bind
with the substrate

Question 17

Describe the effect of temperature on enzyme activity.

Answer 17

as temperature increases, rate of reaction increases
until it reaches the optimum for enzyme activity –
above this temperature enzyme activity decreases and
eventually stops

Question 18

Describe the effect of pH on enzyme activity.

Answer 18

different enzymes have a different optimum pH at which
their activity is greatest – a pH much lower or higher
than this enzyme activity decreases and stops

Question 19

Why do different digestive enzymes have different optimum pHs?

Answer 19

different parts of the digestive system have very
different pHs – the stomach is strongly acidic, and the
pH in the small intestine is close to neutral

Question 20

What is an organ system?

Answer 20

a group of organs working together to perform a specific function