Digestion

Question 1

What helps chemical digestion take place more quickly and how is it achieved

Answer 1

Increase in surface area

Physical digestion breaks food into smaller pieces

Question 2

Describe peristalsis

Answer 2

The process of food passing through the gut

Starts at oesophagus and continues through alimentary canal
Food moves along by contraction of circular muscles in gut wall

Question 3

What is produced in the liver

Answer 3

Bile

Question 4

What is function of gall bladder

Answer 4

Bile stored here before it is released into the small intestine

Question 5

What does large intestine do

Answer 5

Absorb water into bloodstream

By this stage the material in large intestine has had most/all of useful food molecules removed

Question 6

What does small intestine do

Answer 6

Digestion and absorption of useful food molecules into blood

Question 7

Chemical digestion

Answer 7

Uses enzymes to break down large insoluble molecules (carbohydrates,fats and proteins) into smaller molecules

These can then diffuse through walls of small intestine and into blood or lymph

Question 8

How are large insoluble molecules digested in the body

Answer 8

Digested by specific enzymes found in mouth,stomach and small intestine

Question 9

Describe how insoluble carbohydrate digestion starts in the mouth

Answer 9

Carbohydrase enzymes break down large insoluble carbohydrates (long chains of sugar molecules eg. starch)
into small soluble sugars, individual sugar molecules

Question 10

Describe the two-step process of breaking starch down into glucose

Answer 10

Starch (amylase) > maltose
Maltose (maltase) > glucose

Starch breaks to maltose by amylase
Maltose breaks to glucose by maltase

Question 11

In the stomach how are insoluble proteins broken down

Answer 11

Protease enzymes break down large insoluble proteins into smaller peptides
These are ultimately broken down to soluble amino acids

Question 12

Describe purpose of hydrochloric acid in stomach

Answer 12

Released by cells in the wall of stomach

Kills most bacteria in food and creates conditions that help enzymes to work effectively

Question 13

Give example of bacteria that can survive in acidic conditions

Answer 13

Proteus bacterium

Question 14

What does the pancreas produce to digest carbohydrates and proteins

Answer 14

Pancreas produces carbohydrases and proteases for digestion of carbohydrates and proteins

Question 15

How does the pancreas break down fats

Answer 15

The pancreas produces lipase enzymes to break down fats into fatty acids and glycerol

Question 16

Why do protease enzymes work so well in the stomach

Answer 16

Stomach acid provides optimum pH for protease ezymes to work

Other enzymes in the mouth and small intestine require more alkaline pH for optimal acivity

Question 17

Describe how soluble molecules absorbed into blood

Answer 17

Small soluble molecules (produced by digestion) are absorbed into the blood through wall of small intestine
Done mainly through diffusion (some active transport)

Question 18

After soluble molecules enter blood how do they then enter body tissues

Answer 18

Molecules enter blood in small intestine and enters body tissues after being processed by the liver

Question 19

How is the small intestine adapted for efficient absorption of food

Answer 19

Being very long
Possessing thousands of villi and microvilli (on epithelial cell) which increases surface area
Thin lining reduces diffusion distance for dissolved food molecules
Good blood supply from extensive capillary network

Question 20

Why is fat hard to digest

Answer 20

Does not mix easily with water in the intestine

Question 21

Why is bile produced in the body

Answer 21

Emulsifies fat droplets
(breaks big droplets into smaller drops, increase surface area) Enables lipase enzymes to work faster (break down fats into fatty acids and glycerol)

Question 22

Physical digestion

Answer 22

Includes chewing and squeezing food in the stomach to break it into smaller pieces to pass through gut easily