enzymes, digestion and metabolism

Question 1

Define digestion?

Answer 1

The breakdown of large insoluble molecules into small soluble molecules so that they can be absorbed by the small intestine and pass into the blood.

Question 2

How is food moved through the digestive system?

Answer 2

The digestive system is made of a muscular tube that squeezes food through (peristalsis).

Question 3

State the function of the mouth in the digestive system.

Answer 3

Has teeth to chew food into smaller pieces to make it easier to move through the digestive system and to create a larger surface area for enzymes to work on.

Question 4

State the function of the salivary glands.

Answer 4

Adds saliva to moisten food, enabling it to move easily through the oesophagus. The saliva also contains amylase, an enzyme that starts carbohydrate digestion.

Question 5

State the function of the oesophagus.

Answer 5

Muscular tube that contracts and relaxes to push food through to the stomach.

Question 6

State the function of the stomach.

Answer 6

Made of muscular and glandular tissues. The muscles churn the food to mix it with digestive juices released by the glandular tissue.

Question 7

State the function of the liver.

Answer 7

Produces bile.

Question 8

State the function of the gall bladder.

Answer 8

Stores bile and releases it into the small intestine where it emulsifies lipids and neutralises hydrochloric acid.

Question 9

State the function of the small intestine.

Answer 9

This is where small soluble molecules are absorbed into the blood. Produces all three digestive enzymes.

Question 10

State the function of the pancreas.

Answer 10

Produces all three digestive enzymes and releases them into the small intestine.

Question 11

State the function of the large intestine.

Answer 11

Where water is absorbed from undigested food and faeces is formed.

Question 12

State the function of the rectum.

Answer 12

Where faeces is stored before it is egested (pushed out of the body).

Question 13

Name 2 glands in the digestive system.

Answer 13

Pancreas and salivary gland.

Question 14

Where in the digestive system are small soluble molecules absorbed?

Answer 14

Small intestine.

Question 15

Define diffusion.

Answer 15

The net movement of particles from a high concentration to a low concentration.

Question 16

State three ways that the small intestine is adapted to enable rapid diffusion.

Answer 16

Large surface area, good blood supply, short diffusion distance.

Question 17

What is an enzyme?

Answer 17

They are proteins that act as biological catalysts that speed up reactions.

Question 18

Name the three main groups of enzymes found in the digestive system.

Answer 18

Carbohydrases, proteases, lipases.

Question 19

Complete the table for Carbohydrase.

Answer 19

Substrate: Carbohydrate (e.g. starch)
Products: Simple sugars (e.g. maltose)

Question 20

Complete the table for Protease.

Answer 20

Substrate: Protein
Products: Amino acids

Question 21

Complete the table for Lipase.

Answer 21

Substrate: Lipids
Products: Fatty acids and glycerol

Question 22

State where each digestive enzyme is made.

Answer 22

Carbohydrase – mouth, pancreas, small intestine; Protease – stomach, pancreas, small intestine; Lipase – pancreas, small intestine.

Question 23

What is faeces?

Answer 23

Undigested food with most of the water removed.

Question 24

Name the three compounds that make up all cells.

Answer 24

Carbohydrates, lipids, and proteins.

Question 25

Name the three elements that make up the main compounds found in cells.

Answer 25

Carbon, hydrogen, oxygen.

Question 26

Give two examples of simple sugars.

Answer 26

Maltose and glucose.

Question 27

Give two examples of complex carbohydrates.

Answer 27

Starch and cellulose.

Question 28

Describe the structure of a molecule of lipid.

Answer 28

A lipid is made up of a glycerol molecule and 3 fatty acid molecules.

Question 29

Describe the structure of a protein.

Answer 29

A chain of amino acids.

Question 30

Give 4 functions of protein in the body.

Answer 30

Building cells and tissues, enzymes, antibodies, hormones, haemoglobin.

Question 31

Describe what happens to the structure of an enzyme when it denatures.

Answer 31

The long amino acid chain unravels.

Question 32

Define metabolism.

Answer 32

The sum total of all the reactions that happen in a cell or in the body.

Question 33

What is enzyme specificity?

Answer 33

An enzyme is specific as it has the shape to bind to only one type of substrate.

Question 34

Explain how enzyme specificity allows metabolism to be controlled.

Answer 34

Enzymes are specific to a certain reactant/substrate, so will only breakdown or build up/catalyse specific reactions, enabling metabolism to occur in stages.

Question 35

What is emulsification?

Answer 35

Breaking down large lipid droplets into smaller lipid droplets.

Question 36

Explain why emulsification speeds up the digestion of lipids.

Answer 36

Emulsification creates a larger surface area for the enzyme lipase to work on so it can digest the lipid molecules more quickly.

Question 37

Name the acid produced in the stomach.

Answer 37

Hydrochloric acid.

Question 38

Name the enzyme produced by the stomach.

Answer 38

Protease.

Question 39

Give the two roles of acid in the stomach.

Answer 39

To kill bacteria and to create the correct/optimum pH for the protease enzyme to work.

Question 40

Explain why the acid needs to be neutralised when it moves to the small intestine.

Answer 40

The enzymes in the small intestine will be denatured by the acidic pH, so to create the optimum pH for these enzymes to work.

Question 41

Name the substance the liver produces.

Answer 41

Bile.

Question 42

Name the organ that stores bile.

Answer 42

Gall bladder.

Question 43

State the name of the organ that bile is released into.

Answer 43

Small intestine.

Question 44

Give the two functions of bile.

Answer 44

To emulsify fats/lipids and to neutralise hydrochloric acid that has entered the small intestine from the stomach.

Question 45

What is the structure of a lipid in a liquid state?

Answer 45

In a liquid, the lipid is described as an oil, with molecules randomly arranged and medium forces of attraction.

Question 46

What is the structure of a lipid in a solid state?

Answer 46

In a solid, the lipid is described as being a fat, with molecules arranged in rows and strong forces of attraction.

Question 47

Fill in the table for Starch.

Answer 47

Food found in: Celery, potato, lettuce leaves Function in cells: A store of glucose.

Question 48

Fill in the table for Lipids.

Answer 48

Food found in: Any food containing fat Function in cells: Part of cell membranes.

Question 49

Fill in the table for Sucrose.

Answer 49

Food found in: Any food containing sugar Function in cells: Broken down to be used in respiration for the release of energy.

Question 50

Fill in the table for Protein.

Answer 50

Food found in: Any food containing protein Function in cells: Building and repairing tissues.

Question 51

What is the positive result for starch testing?

Answer 51

Blue-black.

Question 52

What is the negative result for starch testing?

Answer 52

Orange/brown.

Question 53

What is the positive result for simple sugars testing?

Answer 53

Red/Orange/Green.

Question 54

What is the negative result for simple sugars testing?

Answer 54

Blue.

Question 55

What is the positive result for lipids testing?

Answer 55

A white emulsion is formed.

Question 56

What is the negative result for lipids testing?

Answer 56

Colourless.

Question 57

What is the positive result for protein testing?

Answer 57

Lilac/Purple.

Question 58

What is the negative result for protein testing?

Answer 58

Blue.