2.5 - Digestion

Question 1

What is the function of the oesophagus?

Answer 1

Gullet has circular muscles in its wall which contract and squeeze behind the food to push it along- peristalsis

Question 2

What is the function of the stomach?

Answer 2

Release food into the small intestine

• gastric juices contain pepsin which breaks down proteins
• hydrochloric acid kills bacteria

Question 3

What is the function of the duodenum? (Small intestine)

Answer 3

Receives pancreatic juice which acts on all classes of food. It contains sodium carbonate which neutralises the acid

Question 4

What is the function of the Ileum? (SI)

Answer 4

Digested food is absorbed

• has a large surface area caused by villi to allow fast absorption
• thin lining to allow digested food to rapidly into the bloodstream

Question 5

What is the function of the liver?

Answer 5

The liver cells make bile and its salts emulsify the lips which can be more easily broken down by lipases

Question 6

What is the function of the pancreas?

Answer 6

Enzymes in the pancreas secrete into the small intestine

Question 7

What is the function of the colon?

Answer 7

Breaks down part of the fibre into fatty acids which the colon can absorb. The colon also absorbs water from undigested material

Question 8

What is the function of a rectum?

Answer 8

-semi-solid waste or stools is passed out into the rectum by peristalsis - egestion

Question 9

Chemical digestion of carbohydrates

Answer 9

They are broken down inti simple sugars by carbohydrases in the small intestine and mouth

Question 10

Chemical digestion of proteins

Answer 10

They are broken down into amino acids by proteases in the stomach and small intestine

Question 11

Chemical digestion of lipids

Answer 11

They are broken down into fatty acids and glycerol by lipases in the small intestine

Question 12

When does assimilation occur?

Answer 12

Where the body cells will take the separate soluble molecules and build up structures needed by cells

Question 13

With visking tubes, how are the tubes similar to the gut of an organism?

Answer 13

Molecules diffuse from small intestine into the blood and the gut contains enzymes
-mixture of large and small molecules

Question 14

What features of a real gut are missing from the Visking tubes?

Answer 14

-no Villi and there is no blood

Question 15

What is the function of the mouth?

Answer 15

Allows the food to be chewed and produces saliva

Question 16

What is the use for starch, proteins and fats?

Answer 16

Starch to provide energy

• proteins for growth and repair
• fats to store and provide energy

Question 17

How to test for glucose, protein and starch?

Answer 17

Protein- add blue biuret to food in a test tube, will turn lilac

• glucose add blue Benedicts solution and place test tube in boiling water bath for 5 mins, turns green, orange then brick red
• starch = add brown iodine to food, turns blue-black

Question 18

What is the function of the bile duct?

Answer 18

Carries bile to the small intestine

Question 19

What is peristalsis?

Answer 19

How food is moved along the digestive system by the contraction of muscles in the gut wall

Question 20

What are the conclusions from the Visking tube?

Answer 20

• starch, fat and protein molecules are too big to pass through the holes in the Visking membrane
• Glucose molecules are small enough to pass through the holes in the tubing

Question 21

What does bile ‘emulsifies’ fats mean?

Answer 21

-breaking down large droplets of fat to smaller droplets which increases the surface area of the fats for the enzyme lipase to work on

Question 22

What happens to the oil after first placing it on the water and then after adding detergent?

Answer 22

First it sits on the surface in a circular shape then doesn’t
= oil is fats
Detergent = bile

Question 23

Function of gall bladder

Answer 23

To store bile produced by the liver