7. Human Nutrition

Question 1

Describe what is meant by a balanced diet

Answer 1

Consists of all of the food groups in the correct proportions

Question 2

List the 7 food groups

Answer 2

1. Carbohydrates
2. Proteins
3. Lipids
4. Vitamins
5. Minerals
6. Dietary Fibre
7. Water

Question 3

State the principal dietary sources and describe the importance of: Carbohydrates

Answer 3

• Importance/function: Main source of energy
• Dietary sources: Bread, cereals, pasta

Question 4

State the principal dietary sources and describe the importance of: Proteins

Answer 4

• Importance/function: Growth and repair
• Dietary sources: Meat, fish, eggs

Question 5

State the principal dietary sources and describe the importance of: Lipids

Answer 5

• Importance/function: Insulation and energy storage
• Dietary sources: Oil, butter, nuts

Question 6

State the principal dietary sources and describe the importance of: Vitamin C & D

Answer 6

1. Vitamin C
   - Importance/function: Forming an essential part of collagen protein (this makes skin, hair, gums & bones)
   - Dietary sources: Citrus fruits, green vegetables, strawberries
2. Vitamin D
   - Importance/function: Helps the body to absorb calcium for strong bones and teeth
   - Dietary sources: Eggs, liver, dairy products, also natural sun

Question 7

State the principal dietary sources and describe the importance of: Mineral Ions - Iron and Calcium

Answer 7

1. Calcium
   - Importance/function: For strong teeth and bones + involves in the clotting of blood
   - Dietary sources: Milk, cheese, eggs
2. Iron
   - Importance/function: To make haemoglobin which transports oxygen
   - Dietary sources: Red meat, liver, leafy green vegetables

Question 8

State the principal dietary sources and describe the importance of: Dietary Fibre

Answer 8

• Importance/function: Provides bulk (roughage) for the intestine to push through it
• Dietary sources: Vegetables, whole grains

Question 9

State the principal dietary sources and describe the importance of: Water

Answer 9

• Importance/function: For chemical reactions to take place in cells
• Dietary sources: Water, juice, milk, fruits and vegetables

Question 10

State the causes of scurvy

Answer 10

• Severe vitamin C deficiency
• Treatment: Oral or intravenous vitamin C supplements

Question 11

State the causes of rickets (poor bone development)

Answer 11

• Severe lack of vitamin D
• Treatment: Increase consumption of foods containing calcium and vitamin D or vitamin D supplements

Question 12

List the main organs of the digestive system; limited to alimentary canal

Answer 12

1. Mouth
2. Oesophagus
3. Stomach
4. Small intestine (duodenum and
   ileum)
5. Large intestine (colon, rectum,
   anus)

Question 13

List the main organs of the digestive system; limited to associated organs

Answer 13

1. Salivary glands
2. Pancreas
3. Liver
4. Gall bladder

Question 14

Describe the functions of: Salivary glands

Answer 14

• Amylase in saliva digests starch into maltose
• Lubricates the food for easy swallowing

Question 15

Describe the functions of: Oesophagus

Answer 15

Food is forced downwards by contractions of the walls; Peristalsis

Question 16

Describe the functions of: Stomach

Answer 16

• Digestion of proteins by protease
• Hydrochloric acid provides a pH for the enzymes and also destroys any pathogens

Question 17

Describe the functions of: Liver

Answer 17

Produces bile which aids fat digestion and neutralises the stomach acid

Question 18

Describe the functions of: Gallbladder

Answer 18

Stores bile before being released into the duodenum via the bile duct

Question 19

Describe the functions of: Pancreas

Answer 19

Produces amylase, protease and lipase before being released into the duodenum

Question 20

Describe the functions of: Duodenum

Answer 20

-* Acidic contents are neutralised by bile to slightly alkaline
- Enzymes complete chemical digestion

Question 21

Describe the functions of: Ileum

Answer 21

Food and water are absorbed into the blood via villi in the lining of the ileum

Question 22

Describe the functions of: Colon

Answer 22

• Remaining water is absorbed from food into the blood,
• Solid waste left forms faeces

Question 23

Describe physical digestion

Answer 23

The breakdown of food into smaller pieces without chemical change to the food molecules

Question 24

State the effect and reason of physical digestion on the surface area of the food

Answer 24

Physical digestion increases the surface area of food for the action of enzymes in chemical digestion

Question 25

List the 4 types of human teeths

Answer 25

1. Incisor 2. Canine 3. Premolar 4. Molar

Question 26

State the functions of each type of human teeths

Answer 26

1. Incisors: Chisel-shaped for biting and cutting 2. Canines: Pointed for tearing, holding and biting 3. Premolars: Large, flat surfaces with ridges at the edges (2 cusps and 1-2 roots) for tearing and grinding up food 4. Molars: Larger, flat surfaces with ridges at the edges (4-5 cusps and 2-3 roots) for chewing and grinding up food

Question 27

Describe the function of the stomach in physical digestion

Answer 27

Contracts its muscles to physically squeeze and mix the food with strong digestive juices (e.g. protease) made by the glandular tissue for the digestion of food

Question 28

Outline the role of bile in emulsifying fats and oils to increase the surface area for chemical digestion

Answer 28

- Neutralise hydrochloric acid since its alkaline - Increase the surface area for chemical digestion by emulsification, allowing lipase to break down lipids into glycerol and fatty acids faster

Question 29

Describe chemical digestion

Answer 29

The breakdown of large insoluble molecules into small soluble molecules

Question 30

State the role of chemical digestion

Answer 30

To produce small solubles that can be absorbed

Question 31

Describe the functions of enzymes: amylase, protease and lipase

Answer 31

1. Amylase: Break down starch to simple reducing sugars molecules 2. Proteases: Break down protein to amino acids 3. Lipase: Break down fats and oils (lipids) to fatty acids and glycerol

Question 32

State where, in the digestive system, amylase, protease and lipase are secreted and where they act

Answer 32

1. Amylase: - secreted by: salivary glands and pancreas - acts in: mouth and duodenum 2. Protease: - secreted by: stomach and pancreas - acts in: stomach and duodenum 3. Lipase: - secreted by: pancreas - acts in: duodenum

Question 33

Describe the functions of hydrochloric acid in gastric juice

Answer 33

1. Killing harmful microorganisms in food: Denatures the enzymes in their cells 2. Providing an acidic pH for optimum enzyme activity: Ensures the pH level/conditions in the stomach is in the optimum range for pepsin to work at its fastest rate

Question 34

Describe the digestion of starch in the digestive system

Answer 34

- Amylase is secreted into the alimentary canal by mouth and duodenum - Amylase breaks down Starch → Maltose - Maltase breaks down Maltose → Glucose (on the membranes of the epithelium lining the small intestine)

Question 35

Describe the digestion of protein by proteases in the digestive system

Answer 35

- Proteases: group of enzymes that break down protein molecules into amino acids - Pepsin produced in the stomach, breaks down protein in the acidic conditions of the stomach - Trypsin produced in the pancreas, breaks down protein in the alkaline conditions of the duodenum

Question 36

Explain the effect of bile being an alkaline mixture

Answer 36

Neutralizes the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action

Question 37

State what a small intestine is

Answer 37

Small intestine: The region where nutrients are absorbed

Question 38

Absorption happens in the colon and small intestine. Which one absorbs water the most?

Answer 38

Small intestine but some is absorbed by the colon

Question 39

Explain the significance of villi and microvilli in increasing the internal surface area of the small intestine

Answer 39

- The adaptations of ileum for absorption is its long length and highly folded surface with millions of villi. These increases the surface area of the ileum allowing an increase in the rate and efficiency of absorption - Microvilli (on the surface of the villi) further increases the surface area for faster absorption of nutrients

Question 40

Describe the roles of capillaries and lacteals in villi

Answer 40

- Blood capillaries: Transports glucose and amino acids away from the small intestine in the blood - Lacteal: Transports fatty acids and glycerol away from the small intestine in the lymph (fat absorption)