Nutrition

Question 1

Nutrients

Answer 1

Chemical substances in the food that are used in the human body

Question 2

Nutrition

Answer 2

The supply of nutrients

Question 3

Malnutrition

Answer 3

A deficiency, imbalance or excess of specific nutrients

Question 4

Diet

Answer 4

The total food intake by an organism

Question 5

Balanced diet

Answer 5

A diet that contains all nutrients

Question 6

Non-essential nutrients

Answer 6

Nutrients that are either made in the body another nutrient or for which other nutrient that can be used for the same purpose exists

Question 7

Essential nutrients

Answer 7

Nutrients that cannot be synthesised by the body so they must be in the diet

Question 8

Amino acids

Answer 8

Of the 20 amino acids about half are essential. Lack of essential amino acids affects protein synthesis. This causes protein deficiency malnutrition- kwashiorkor is a form of protein deficiency

Question 9

Minerals

Answer 9

Chemical elements usually in ionic form that are needed in the diet in relatively small quantities.

Question 10

Vitamins

Answer 10

Chemically diverse carbon compounds needed in very small quantities eg. calciferol and ascorbic acid. They act as cofactors for enzymes and hormones. They are categorised as fat-soluble and water soluble. Water soluble vitamins, like ascorbic acids, are lost in excess in urine. Fat soluble vitamins can be stored in the body

Question 11

Calorimetry

Answer 11

The energy content of food can be measured by burning a sample and measuring the energy released via calorimetry

Question 12

Calorimetry equation

Answer 12

Q=mcΔt

Question 13

Source of error in calorimetry

Answer 13

Unwanted heat loss to the environment.
Improvement: sealed contained instead of an open tube

Question 14

Control of appetite

Answer 14

Centre in the hypothalamus and is responsible for feelings of appetite or satiety

Question 15

Starvation

Answer 15

Prolonged shortage of food. Lack of all nutrients and thus energy deficiency. Body first uses its glycogen and fat reserves and then breaks down its own muscle tissues. Can suffer from marasmus

Question 16

Anorexia

Answer 16

A condition in which an individual voluntarily starves oneself. Muscle tissues are broken down, hair becomes thinner, heart rate and blood pressure are reduced and infertility. Heart muscle is broken down

Question 17

Obesity

Answer 17

An excessive storage of fat in adipose tissue due to prolonged intake of more energy in the diet than is used in cell respiration. People with obesity are more likely to suffer from type II diabetes and hypertension.

Question 18

Vitamin D deficiency

Answer 18

Needed for the absorption of calcium. A lack of vitamin D results in inadequate bone mineralisation due to calcium salts not being deposited or reabsorbed. Vitamin D does not fit the definition of vitamin very well, as it can be synthesised by the skin through sunlight or UV light.
Sources: fish oils, eggs, liver

Question 19

Ascorbic acid deficiency

Answer 19

Needed for the synthesis of collagen fibres. Causes scurvy. Most plants and animals including mammals have the enzymes to synthesise ascorbic acid. It was thought that scurvy was specific to humans but it was falsified when scurvy was induced in guinea pigs

Question 20

Phenylketonuria (PKU)

Answer 20

Phenylalanine is an essential aa, but tyrosine is a non-essential aa. Tyrosine can be synthesised from phenylalanine by the enzyme phenylalanine hydroxylase. Phenylketonuria is a genetic disease: caused by genetic mutations in the gene coding for phenylalanine hydroxylase. The mutated allele is recessive. The result is that phenylalanine accumulates and so there is a deficiency in tyrosine. From birth, the levels of phenylalanine can rise causing reduced head brain growth and mental retardation. phenylalanine levels are routinely tested after birth for immediate treatment. Die with low levels of phenylalanine.
Foods like: meat, fish and nuts can be eaten in small quantities. Tyrosine supplements might also be needed.

Question 21

Cholesterol and coronary heart disease

Answer 21

Cholesterol is a steroid and is a component of cell membranes, synthesis of Vitamin D and steroid hormones and production of bile. There is correlation between levels of cholesterol in blood plasma and increased risk of CHD

Question 22

Why cannot we determine that lowering dietary cholesterol reduces the risk of CHD

Answer 22

-the liver can synthesise cholesterol so dietary cholesterol is not the only source
-genetic factors more important than dietary intake
-positive correlation between dietary intake of saturated fats and intake of cholesterol
-reducing dietary cholesterol often has a small effect on blood cholesterol levels
- drugs are more effective at reducing blood cholesterol levels