Biology Unit 1

Diet and metabolic rate-

A healthy diet contains the right proportions of each food group and enough energy for the individual (but not too much)

The different food groups are:

·         carbohydrates, release energy

·         fats, provides insulation and releases energy

·         protein, for growth and cell repair/ replacement

·         fibre, provides a medium for the intestines to contract against so things move smoothly through the digestive system

·         vitamins

·         mineral ions

Energy is needed to fuel chemical reactions in the body, and the rate of these chemical reactions is known as the metabolic rate. muscle requires more energy than fatty tissue so people with a higher proportion of muscle with have a higher metabolic rate, the larger the person the more energy is needed across the body and therefore the metabolic rate is also higher, and men have both of these attributes to a larger extent and therefore have a higher metabolic rate than women. When you exercise your metabolic rate goes up so people with more active job need to eat more.

Metabolic rate= the sum total of all chemical reactions in the body

Unbalanced diets: people who have out of balance diets are described as malnourished, and are generally extremely under or over weight.

obesity--> caused from excess carbohydrates and is often seem in more developed countries as there is more access to high fat and carb foods. It is a product of over eating and lack of exercise. It causes health problems such as arthritis, type 2 diabetes, high blood pressure and heart disease.

Deficiency diseases--> lack of food causes people to become severely underweight and is common in developing countries, the side effects are dependent upon what food group is lacking but overall deficiency causes stunted growth, fatigue, poor resistance to infection and irregular periods.

Lack of...

·         vitamin c= scurvy... the rotting of gums

·         vitamin d= rickets... weak and often bent bones

·         iron= anaemia

·         calcium= osteoporosis

Exercise increases energy used and decreases the amount of energy stored as fat, it also builds muscle helping to boost metabolic rate yet you can be fit and unhealthy e.g. malnourished but physically fit.

Inherited factors affect health too, for example an underactive thyroid lowers the metabolic rate increasing the risk of obesity. You can also inherit high/low blood cholesterol levels which affects a person's risk of heart disease

With 'slimming' claims on foods it is important to check if it was published in a reputable journal, written by a qualified person who is not connected to the seller (so not biased), was the sample of people tested large enough to give reliable results and whether there have been other tests conducted giving similar results.

Fighting Diseases-

Bacteria are very small cells that damage cells and produce toxins.

Viruses are the smallest pathogen which replicate inside human body cells to the point that the cells burst

Body defence systems are our skin, cilia and…