Diet and Food Production

Question 1

Balanced diet

Answer 1

One that contains all the nutrients required for health in appropriate proportions

Question 2

Malnutrition

Answer 2

Caused by an unbalanced diet. Can be deficiency, however the most common form of malnutrition is obesity

Question 3

Obesity

Answer 3

Caused by consuming too much energy. The excess energy is deposited as fat in the adipose tissues. Obesity is when the excess fat deposited impairs health, and is usually when someone’s BMI is over 30. If fat is around your middle, you are more at risk than someone whose fat is around their hips and thighs

Question 4

Linking diet and coronary heart disease

Answer 4

• excess salt decreases the water potential of the blood, so more water is held there and blood pressure increases. This can damage artery linings, one of the early steps in the process of atherosclerosis
• excess cholesterol and fats are very bad. See another flash card for this. Too long for this one

Question 5

Cholesterol and different types of fats and coronary heart disease

Answer 5

• Cholesterol is transported in the blood as High-density lipoproteins: (HDLs, made from unsaturated fats, cholesterol and protein) and Low-density lipoproteins (LDLs, made for saturated fats, cholesterol and protein).
• HDLs take cholesterol from tissues to liver (receptors on liver cells receive them to be broken down/in bile) - hooray, its going to lower blood cholesterol levels, and maybe remove fatty depositions in artery walls!
• LDLs take cholesterol from liver to tissues. (receptors on tissue cells receive them) Don’t want too many of these, or there will be deposition in the artery walls
• Saturated fats decrease activity of LDL receptors, so will be more LDLs in the blood (they’re made of sat. fats as well - vicious circle)
• Poly/mono unsaturated fats increase activity of LDL receptors - less in blood!

Question 6

What do humans depend on for food?

Answer 6

Plants! - they are the basis of all food chains. They carry out photosynthesis, converting the energy from sunlight to a stored chemical form. Absorb carbon dioxide from starch to make carbohydrates.

Question 7

Selective breeding in plants

Answer 7

We select individuals with the desired characteristics (e.g. growth rate, yield, disease/pest resistance etc) and only save certain plant seeds for sowing. This means, we get an improved batch next generation. With new technology, sections of DNA can be used as a marker, so selection can occur at an early stage. Tomatoes have been selectively bred by finding wild tomatoes with resistance to ‘yellow leaf curl virus’ and selectively breeding them into a domestic variety.

Question 8

Selective breeding in animals

Answer 8

We select individuals with the desired characteristics (e.g. egg production, milk production, meat quality, disease resistance) and only allowing these animals to breed. With new technology, sections of DNA can be used as a marker, so selection can occur at an early stage.

Question 9

Use of fertilisers in food production

Answer 9

Fertilisers replace minerals in the soil which may have been used by previous crops. They may contain nitrates, potassium and phosphate. They increase growing rate and size of crops

Question 10

Use of pesticides in food production

Answer 10

Pesticides are designed to kill disease causing organisms in crops that would reduce the yield or kill the crop. Examples are fungicides and dipping sheep to kill ticks

Question 11

Use of antibiotics in food production

Answer 11

Reduces spread of disease among animals that are farmed close together, as the diseases could reduce growth performance and impair reproduction

Question 12

Advantages of using microorganisms to make food for human consumption

Answer 12

• Production of protein is many times faster than with animal/plant protein
• Production can be increased/decreased according to demand
• Good source of protein for vegetarians
• Protein doesn’t contain animal fat/cholesterol
• SCP (single-celled protein used directly as food) production could be combined with removal of waste products, as the micro-organism can grow on waste materials, e.g. paper and whey

Question 13

Disadvantages of using microorganisms to make food for human consumption

Answer 13

• People don’t want to eat fungal protein/food grown on waste
• Isolation of the protein: the microorganisms are grown in huge fermenters and need to be isolated from the material on which they grow
• The protein has to be purified to avoid contamination
• Infection: conditions for microorganisms to grow are ideal for pathogenic organisms - have to insure culture isn’t infected (but meat can also me contaminated..!)
• Palatability - protein doesn’t taste like or have the same texture as traditional protein

Question 14

Salting, adding sugar to prevent spoilage

Answer 14

Dehydrates the microorganisms, as water leaves them by osmosis, due to the low water potential of the outside environment. Kills bacteria

Question 15

Pickling to prevent spoilage

Answer 15

An acid pH is used to kill microorganisms by denaturing their enzymes and other proteins

Question 16

Freezing to prevent spoilage

Answer 16

Don’t kill microorganisms! Slow down enzyme activity metabolism, growth and reproduction is very slow

Question 17

Heat treatment to prevent spoilage

Answer 17

Heat denatures enzymes and other proteins, killing microorganisms

Question 18

Irradiation to prevent spoilage

Answer 18

Ionising radiation kills the micro-organisms by disrupting their DNA structure