Enzymes and Digestion

Question 1

What is the function of glucose?

Answer 1

Short-term energy supply which is used for respiration.

Question 2

What is starch?

Answer 2

Chains of glucose molecules, which get broken down into glucose for respiration.

Question 3

What is the function of protein?

Answer 3

• Maintain cell function.

* Growth and repair of cells and tissues.

Question 4

What is the function of lipids?

Answer 4

Long-term energy storage.

Question 5

What is the function of fibre?

Answer 5

• In plants - make up cell walls.

* In humans - keep digestive system healthy and prevent constipation.

Question 6

What is the function of minerals?

Answer 6

Make healthy bones and blood.

Question 7

What is the function of vitamins?

Answer 7

Take part in important chemical reactions in the body.

Question 8

What is the function of water?

Answer 8

Carry substances around the body and replace lost water.

Question 9

How can you test for glucose?

Answer 9

By using Benedict’s reagent, which will turn from blue to brick red when heated if glucose is present.

Question 10

How can you test for starch?

Answer 10

By using iodine, which will turn from brown/yellow to blue/black when if starch is present.

Question 11

How can you test for protein?

Answer 11

By using Biuret reagent, which will turn from light blue to purple if protein is present.

Question 12

What can a deficiency in Vitamin A cause?

Answer 12

Night blindness - degeneration of rod cells in the retina.

Question 13

What can a deficiency in Vitamin C cause?

Answer 13

Scurvy - loss of teeth, gum bleeding, poor wound healing.

Question 14

What can a deficiency in Vitamin D or calcium cause?

Answer 14

Rickets - brittle bones, bow legs, poor teeth.

Question 15

What can a deficiency in iron cause?

Answer 15

Anaemia - low energy levels, dizziness.

Question 16

What can a deficiency in protein cause?

Answer 16

Kwashiorkor - swollen belly, poor muscle growth, weight loss.

Question 17

What can a deficiency in iodine cause?

Answer 17

Goitre - swollen lump in thyroid gland, slow metabolism.

Question 18

How is energy in food used?

Answer 18

• Movement - kinetic energy.
• Body heat - heat energy.
• Growth and repair - chemical energy.

Question 19

What is the structure of lipids?

Answer 19

1 part glycerol to 3 parts fatty acids.

Question 20

Why can energy requirements differ with each person?

Answer 20

They very with activity levels, age, temperature, pregnancy, e.t.c.

Question 21

What is the function of the mouth, teeth and tongue?

Answer 21

Starting point of digestion, where the teeth break up food particles mechanically and the tongue mix food with saliva.

Question 22

What is the function of the oesophagus?

Answer 22

Transport of food to stomach.

Question 23

What is the function of the stomach?

Answer 23

Storage and digestion of food.

Question 24

What is the function of the duodenum?

Answer 24

Main digestion of food.

Question 25

What is the function of the pancreas?

Answer 25

Secretes digestive juices and enzymes.

Question 26

What is the function of the gall bladder?

Answer 26

Site of bile salt storage.

Question 27

What is the function of the liver?

Answer 27

Site of bile salt production.

Question 28

What is the function of the ileum (small intestine)?

Answer 28

Main absorption of nutrients.

Question 29

What is the function of the large intestine?

Answer 29

Absorption of water.

Question 30

How does food move along the digestive system?

Answer 30

Peristalsis - | • series of wave-like muscle contractions that moves food along the digestive system

Question 31

How is absorption made efficient in the digestive system?

Answer 31

• Large surface area - the ileum is lined by thousands of villi and there are thousands of microvilli on each cell of the villus wall. • Short diffusion distance - the villus wall is very thin (1 layer of cells thick) - blood vessels are directly under the villus wall • High concentration gradient - continuous flow of blood which requires nutrients - peristalsis brings along food constantly

Question 32

What are enzymes?

Answer 32

Proteins that speed up chemical reactions (biological catalysts).

Question 33

How do enzymes work?

Answer 33

* Each enzyme binds to its substrate at the active site. * An enzyme-substrate complex forms. * Reaction takes place. * Product no longer fits into active site and is released. * Enzyme can be used again.

Question 34

Why are enzymes useful?

Answer 34

They speed up the breakdown of molecules.

Question 35

What factors affect enzyme activity?

Answer 35

* Temperature - at around 40°C, after that the enzymes denature. * pH.

Question 36

How is starch digested?

Answer 36

* In the mouth, starch is digested into maltose by carbohydrase (produced in the salivary glands). * In the duodenum, maltose is digested into glucose by carbohydrase (produced in the pancreas and duodenum).

Question 37

How is protein digested?

Answer 37

* In the stomach, the enzyme protease (pepsin), made in the stomach lining, digests protein into amino acids. * In the duodenum, the enzyme protease (trypsin), made in the pancreas, digests protein into amino acids.

Question 38

How are lipids digested?

Answer 38

• In the duodenum, the enzyme lipase, made in the pancreas, digests lipids into glycerol and fatty acids.

Question 39

What role does bile play in digestion?

Answer 39

* Bile neutralises the pH of food when it exits the stomach and enters the duodenum so that enzymes are not denatured and can digest the food. * Bile emulsifies lipids into droplets to increase the surge area and help with lipase action.

Question 40

Where is bile produced and stored.

Answer 40

Bile is produced by the liver and stored in the gall bladder.

Question 41

What is the function of iron?

Answer 41

Iron is a component of haemoglobin (in red blood cells) and helps to transport oxygen. Iron is needed in order for your body to carry out respiration.

Question 42

How are amino acids absorbed into the bloodstream?

Answer 42

They are absorbed into the blood by active transport against the concentration gradient using energy (from respiration).

Question 43

What can happen to make someone's faeces very separate hard lumps?

Answer 43

• Lack of water - lots of water is reabsorbed. • Lack of fibre. (constipation)

Question 44

What can happen to make someone's faces very watery with no solid pieces

Answer 44

• Food poisoning/infection. • Too little water absorbed. (diarrhoea)

Question 45

What health problems can someone develop with too much fat in their diet?

Answer 45

* High blood pressure (clogged arteries). * Increased risk of heart attack. * Obesity. * Diabetes. * Stroke.

Question 46

Why is snacking on crisps, chocolate and soft drinks an unsuitable diet for an inactive child?

Answer 46

Too many calories are consumed and all will not be burned/used up.