Digestive System

Question 1

What is a tissue?

Answer 1

A group of cells.

Question 2

What are organs made of?

Answer 2

Tissues.

Question 3

What does the pancreas contain?

Answer 3

• Hormones to control blood sugar.

- Some digestive enzymes.

Question 4

How are the villi in the small intestine adapted?

Answer 4

• A large surface area to absorb soluble food molecules by diffusion and active transport.
• A thin wall for a short diffusion path.
• A good blood supply to carry food molecules away to maintain a concentration gradient.

Question 5

What happens in the liver?

Answer 5

Bile is produced.

Question 6

What happens in the small intestine?

Answer 6

• Absorption of food occurs through the villi.

- Enzymes are released.

Question 7

What happens in the large intestine?

Answer 7

Water is absorbed, producing faeces.

Question 8

What are carbohydrates made of?

Answer 8

Units of sugar.

Question 9

Why are starch and cellulose complex carbohydrates?

Answer 9

They are made of long chains of simple sugar units.

Question 10

What are lipids made of?

Answer 10

Three molecules of fatty acids linked to a molecule of glycerol.

Question 11

What proteins made of?

Answer 11

Long chains of amino acids.

Question 12

What are all chemical reactions in cells controlled by?

Answer 12

Proteins called enzymes.

Question 13

What are enzymes?

Answer 13

Proteins.

Question 14

What can enzymes do?

Answer 14

• Build large molecules from smaller ones, such as starch from glucose.
• Change one molecule into another.
• Break down large molecules into smaller ones.

Question 15

What do digestive enzymes do?

Answer 15

Break down large molecules into smaller ones.

Question 16

What is the effect of pH on enzyme action?

Answer 16

-pH affects the forces which hold the folded shape of the protein molecule in place. So, the shape of the active site changes - DENATURED.

Question 17

How does an enzyme work best at optimum pH?

Answer 17

Its active site has the best shape so can work most efficiently.

Question 18

Where are digestive enzymes produced?

Answer 18

By specialised cells in glands and in the lining of the small intestine.

Question 19

Where do digestive enzymes work, unlike most enzymes?

Answer 19

Outside of the cells.

Question 20

How does pH change throughout the digestive system?

Answer 20

• In the mouth and the small intestine, it is alkaline.

- In the stomach it is acidic.

Question 21

Where is amylase produced and what does it do?

Answer 21

It is produced by the salivary glands, the pancreas and the small intestine. It catalyses the digestion of starch (breaks it down) into to glucose (sugars) in the mouth and small intestine.

Question 22

Where is protease produced and what does it do?

Answer 22

It is produced by the stomach, pancreas and the small intestine. It catalyses the breakdown of proteins into amino acids in the stomach and small intestine.

Question 23

Where is lipase produced and what does it do?

Answer 23

It is produced by the pancreas and the small intestine. It catalyses the breakdown of lipids into fatty acids and glycerol.

Question 24

At what temperature does the human digestive system work best?

Answer 24

37*C (body temperature).

Question 25

At what pH do protease enzymes work best at?

Answer 25

Acidic pH (in the stomach).

Question 26

At what pH do other proteases, amylase and lipase work best at?

Answer 26

Slightly alkaline pH (in the small intestine).

Question 27

Where is bile produced, where is it stored, and where is it released into?

Answer 27

Bile is produced in the liver, stored in the pancreas, and released into the small intestine.

Question 28

What is the function of bile

Answer 28

Bile:

• Neutralises the stomach acid.
• Makes the conditions in the small intestine slightly alkali.
• Emulsifies fats to increase their surface area for lipase enzymes to work on.

Question 29

What three tissues are found in the stomach and what are their functions?

Answer 29

Muscular tissue - contracts to bring about movement.

Glandular tissue - produces substances such as enzymes or hormones.

Epithelial tissue - covers the inner and out surfaces of the stomach.