Diet and food production

Question 1

What is a balanced diet?

Answer 1

A diet that contains all the nutrients required for health in appropriate proportions.

Question 2

What are the components of a balanced diet?

Answer 2

1. Carbohydrates: Main source of energy.
2. Proteins: Growth repair of muscles and body tissues.
3. Fats: Form of energy storage as well as used for many other roles including insulation and producing new cells.
4. Vitamins: Important chemical components of metabolic processes.
5. Minerals: Inorganic chemicals and ions used for making essential substances.
6. Water: Solvent for metabolic reactions and also used for many other roles like transport.
7. Fibre and roughage: Important for maintaining a healthy and strong digestive system.

Question 3

What causes malnutrition?

Answer 3

• They do not have regular access to food so they are deficient in all aspects of their diets, especially energy.
• They have restricted access to food and rarely consume certain vital nutrients, resulting in deficiencies in those areas.
• They have too much of some, if not, all essential nutrients which leads to the body taking drastic measures in reducing or storing those nutrients.

Question 4

What are the causes of obesity?

Answer 4

1. An individual consumes too much foods high in energy and/ or isn’t actively expending that energy.
2. Energy consumed is in excess of energy expended, so there is a surplus of energy.
3. Body stores excess of energy in the form of fats deposited in adipose tissue.
4. Build up of fat in adipose tissue leads to obesity which may increase risk of developing other health problems.

Question 5

What is your BMI?

Answer 5

Body mass index. It is a measure of body mass against height squared and is used to determine whether a person is overweight, underweight or normal weight.

Question 6

What problems may be caused by obesity?

Answer 6

1. Cancer.
2. Cardiovascular disease.
3. Type 2 diabetes.
4. Gallstones.
5. Osteoarthritis.
6. Hypertension.

Question 7

What problems may an excess salt diet cause?

Answer 7

Too much salt lowers the water potential of blood which causes more water to be held in the blood. This increases the volume in blood and causes hypertension, which may damage arterial endothelia and contribute towards atherosclerosis.

Question 8

What problems may an excess fats diet cause?

Answer 8

An excess in fats will often increase the body’s production of lipoproteins which may cause atherosclerosis. Saturated fats produce low density lipoproteins (unhealthy) and unsaturated fats produce high density lipoproteins (healthy).

Question 9

How is cholesterol carried in the body?

Answer 9

• Cholesterol is a lipid, so it is not soluble in water and cannot be carried directly in blood.
• Cholesterol can be combined with proteins and other lipids to create the water soluble lipoproteins that can be transported directly in blood.
• There are two types of lipoproteins; high density lipoproteins (HDLs) and low density lipoproteins (LDLs).

Question 10

What is the function of HDLs?

Answer 10

• HDLs are made from a combination of proteins, unsaturated fats and cholesterol.
• HDLs carry cholesterol from body tissue back to the liver where is is absorbed via receptors, broken down and used for making bile.
• High levels of HDLs is generally associated with reducing cholesterol levels and may even reduce the risk of CHD.

Question 11

What is the function of LDLs?

Answer 11

• LDLs are responsible for carrying cholesterol from the liver to body tissue where they are absorbed by receptors.
• If concentration of LDLs in the blood is too high, and the arterial endothelia are damaged, they may get deposited under the endothelium as atheromas and cause atherosclerosis.

Question 12

How does consuming saturated/ unsaturated fats contribute towards CHD?

Answer 12

• High levels of saturated fats in the blood has been proven to inhibit activity of LDL receptors on cells which slows down intake of LDLs and causes a build-up in the blood, increasing the risk of atherosclerosis.
• High levels of unsaturated fats in the blood has been proven to aid the activity of LDL receptors, increasing the rate of LDL intake and reducing LDL concentration in the blood, decreasing risk of CHD.

Question 13

How does diet affect lipoprotein build-up?

Answer 13

Eating a low fat diet will result in low lipoprotein levels in blood. However, a higher proportion unsaturated fats diet will help reduce the level of LDLs in the blood and reduce risk of CHD.

Question 14

Why do we depend on plants for nutrition?

Answer 14

Plants are autotrophs, they are able to convert simple inorganic molecules into complex organic molecules used for energy and growth. Humans are heterotrophs, so we are unable to produce many essential nutrients, therefore we depend on plants in order to acquire these.

Question 15

How can we improve plant yield in agriculture?

Answer 15

• Improve rate of growth.
• Increase size of each plant.
• Reduce death by disease or pests.
• Making harvesting easier by standardising plant size.
• Improving fertiliser efficiency.

Question 16

How can we improve animal yield in agriculture?

Answer 16

• Improve rate of growth.
• Increase productivity (for animal products).
• Increase disease resistance.

Question 17

What is the process of selective breeding?

Answer 17

1. The plant/animal with a desired characteristic is selected from the population by observation or genetic analysis (identifying the genotype responsible for the phenotype).
2. Find another individual with the desired characteristic and breed the 2 individuals together; either by isolation or artificial fertilisation.
3. From the offsprings, select the ones with the desired characteristic and breed them together.
4. Repeat process for many generations and the characteristic will become more exaggerated.

Question 18

How do fertilisers improve yield?

Answer 18

Fertilisers contain vital minerals like magnesium, nitrates, phosphates… which may be deficient in soil, increasing plant rate of growth and size.

Question 19

How do pesticides improve yield?

Answer 19

Plants: Pesticides are able to kill any pests that may compete with plants for nutrients or kill them with disease. This increases number of plants that survive to harvest, improving yield.
Animals: Animals can be treated with regular doses of antibiotics which is able to cure them from many diseases that may affect their rate of growth.

Question 20

How can food be spoilt?

Answer 20

1. Many microorganisms use saprophytic nutrition which involves excreting enzymes to break down food and then absorbing the products. This may reduce food into an inedible mush.
2. Microorganisms may begin growing on food to form visible colonies.
3. Microorganisms living on food may produce toxins that are lethal if ingested.
4. Some microorganisms may cause infections once they enter the body as they are not killed by stomach acid.

Question 21

What methods are used to prevent food spoilage?

Answer 21

1. Cooking: Denatures enzymes and proteins, killing microorganisms causing spoilage.
2. Pasteurising: Denatures enzymes and kills microorganisms that cause food spoilage.
3. Drying/salting/marinating: Decreases water potential of surroundings and dehydrates microorganisms, killing them.
4. Smoking: Dehydrates as well as contains antibacterial agents, killing bacteria.
5. Pickling: Acidity denatures enzymes and proteins, killing microorganisms responsible for spoilage.
6. Irradiation: Ionising radiation kills microorganisms.
7. Cold storage: Decreases enzyme activity significantly and inactivates microorganisms causing spoilage.
8. Canning: Prevents microorganisms from contacting food.
9. Vacuum wrapping: Removes air for aerobic respiration, eventually killing microorganisms.

Question 22

How are microorganisms used in food production?

Answer 22

Microorganisms are used to produce a range of foods including:

• Cheese.
• Yoghurt.
• Bread.
• Alcohol.
• Producing single-cell proteins (SCPs) that can be used directly as food; providing vital nutrients without additional fats.

Question 23

What are the advantages of microorganisms in food production?

Answer 23

• They are faster at producing proteins than plants and animals.
• Production can be increased or decreased easily.
• No animal welfare issues.
• Good source of proteins as a meat substitute.
• Proteins do not contain lipids.
• Can be used as a method of waste disposal.

Question 24

What are the disadvantages if microorganisms in food production?

Answer 24

• Some people don’t like the idea of food being f=grown on waste.
• A complex isolation process is required to separate the microorganisms from the growing medium.
• Conditions required to grow food microorganisms are ideal for pathogenic ones so precautions need to be taken in order to prevent contamination.
• The proteins produced do not produce the same flavour and texture as traditional meats.