B3-Digestion

Question 1

How does temperature effects enzyme controlled reactions ?

Answer 1

Increasing temperature increases rate of reaction up to certain point. This point is called the ‘optimum’ temperature and if it goes higher than this temperature the enzyme will ‘denature’ (bonds are broken) changing the ‘active site’ shape meaning that the reaction stops.

Question 2

How does pH effects enzyme controlled reactions ?

Answer 2

All enzymes have an optimum pH at which they work best. In conditions with a lower or higher pH, the pH starts to interfere with bonds that hold the enzyme in the correct shape causing the ‘active site’ to change shape and therefore stop the reaction.

Question 3

What is the name of the group of enzymes that breakdown carbohydrates into simple sugars?

Answer 3

Amylases

Question 4

What is the name of the group of enzymes that breakdown proteins into amino acids ?

Answer 4

Proteases

Question 5

What is the name of the group of enzymes that breakdown lipids (fats) into glycerol and fatty acids?

Answer 5

Lipase

Question 6

Where in the digestive system is water reabsorbed?

Answer 6

Large intestine

Question 6

Where is bile produced?

Answer 6

The liver

Question 6

Which acid is produced by the stomach?

Answer 6

Hydrochloric acid

Question 6

What are the finger-like projections in the small intestine called?

Answer 6

Villi

Question 6

How is food moved through the gut?

By peristalsis
By gravity
By waves of liquid

Answer 6

By peristalsis

Question 7

The enzyme that starts the chemical digestive process at the mouth is..

Answer 7

Amylases (for the starch)

Question 8

Before it is Egested, faeces is retained in the …

Answer 8

Rectum

Question 9

Absorption of carbohydrates, proteins and lipids occurs in the…

Answer 9

Small intestine

Question 10

Which solution can be used to test for starch?

Answer 10

Iodine solution

Question 11

Where in the digestive system are lipase enzymes produced

Answer 11

Pancreas and small intestine

Question 12

Why is bile needed?

Answer 12

• to emulsify fats

- to raise the pH of the stomach so the enzymes aren’t denatured

Question 13

Protease break down……. into ……

Answer 13

Protein into amino acids

Question 14

Lipase break down …… into …..

Answer 14

Lipids into glycerol and fatty acids

Question 15

What is the name of the area where the enzyme binds to the substrate?

Answer 15

The active site

Question 16

What do you call it when the substrate has reached the active site of the enzyme?

Answer 16

Enzyme-substrate complex

Question 17

The “lock and key” model shows how the …..

Answer 17

Substrate binds onto the active site

Question 18

What is the function of hydrochloric acid in the stomach?

Answer 18

To provide the optimum pH for the working enzymes in the stomach

Question 19

Why is it necessary to breakdown large insoluble food molecules into smaller soluble molecules?

Answer 19

• as they cant be absorbed into the bloodstream
• small, soluble molecules can be absorbed into the blood stream to construct new carbohydrates, proteins and lipids in the body
• some glucose produced by digestion is used for respiration

Question 20

Why are enzymes important in the metabolism of cells or organisms?

Answer 20

Chemical reactions needed for life could not take place fast enough without enzymes to speed them up

Question 21

Explain why emulsification is important?

Answer 21

Fats do not mix with other liquids in digestive system, staying as large molecules that are hard for lipase enzymes to act on.
Larger surface area produced by bile action
allows enzymes to reach more fat molecules and break them down more quickly.