AQA GCSE- Biology 1.1

Core Science 1.1

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Biology Unit B1.1 Diet and exercise
A healthy diet contains the right balance of the different foods you need and the right amount of energy
and the different food groups are...
Carbohydrates and fats are needed to provide energy for your body chemistry to function correctly, and to
keep you warm at 37oC,
o But too excessive fats or carbohydrates build up in your body which can lead to obesity.
o Obesity can cause health issues: arthritis, diabetes, high blood pressure and heart disease
o Too much saturated fat in a diet causes blood cholesterol levels to rise, leading to higher blood pressure
Proteins are used by the body to build cells - growth of new tissue, cell repair and cell replacement.
Mineral ions and vitamins are needed in small amounts for healthy functioning of the body - organs, skin,
bones etc.
o You need mineral salts, but too much salt can cause high blood pressure and heart problems.
Fibre keeps everything moving smoothly through your digestive system.
A person is malnourished if their diet is not balanced, it's common in the poorer developing countries.
The effects of malnutrition depend on what is missing from the diet but common symptoms are slow growth
in children, weight loss in adults, poor resistance to disease and infection and fatigue. Deficiency diseases are
caused by lack of specific vitamins or minerals.
Starvation is when there is not enough food to maintain life.
An unbalanced diet may also lead to deficiency diseases or conditions such as Type 2 diabetes.
To maintain a healthy body you have to eat the right amounts and types of food.
A person loses mass when the energy content of the food eaten is less than the energy expended by the body.
You need energy to fuel the chemical reactions in your body to keep you alive, these reactions are called your
metabolism. Different people have small differences in their resting metabolic rates because:
o Muscle needs more energy than fatty tissue, so more muscular people tend to have a higher metabolic
rate because of the higher ratio of muscle to fat.
o Bigger people tend to have a higher metabolic rate because more energy is needed to maintain a greater
mass of cells.
o Usually men have a greater metabolic rate because they tend to have a greater proportion of muscle.
o Exercise increases the amount of energy expended (used) by the body.
People need different amounts of energy:
o Athletes or people engaged in heavy manual work would need a greater energy (calorie) intake.
o People who do little exercise and have a job sitting in an office should reduce their carbohydrates and fats
intake accordingly because you need less energy to get through the day.
The rate at which all the chemical reactions in the cells of the body are carried out (the metabolic rate)
varies with the amount of activity you do and the proportion of muscle to fat in your body.
Inherited factors
Metabolic rate may be affected by inherited factors, e.g. an underactive thyroid gland which can lower metabolic
rate, increase fatigue and ultimately cause obesity. Any energy not used will be stored as fat.
People can inherit factors that affect the blood cholesterol level, cholesterol is an essential fatty substance for good
health and it's in every cell in the body but if it is too high it causes fatty deposits on the inner surfaces of blood vessels
causing higher blood pressure and heart disease
Regular exercise lowers your cholesterol levels, lowering harmful cholesterol and increasing good cholesterol, lowering
the risk of heart disease and other health problems.

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How our bodies defend themselves against infectious diseases
He worked in Vienna General Hospital in the 1840s and witnessed large numbers of women dying after
childbirth from a puerperal fever disease.
He thought that the hospital staff were spreading the disease via unwashed hands.
After instructing doctors and nurses to wash their hands in an antiseptic solution, the mortality rate was
considerably reduced.
Although he didn't realise it at the time, the antiseptic solution was killing the infecting bacteria.…read more

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Antibiotics, including penicillin, are medicines that help to cure bacterial disease by killing infectious bacteria
inside the body.
Antibiotics cannot be used to kill viral pathogens (viruses)
Anti-viral drugs may attack good cells too, so it's difficult to develop drugs that kill viruses without also
damaging the body's tissues.
Different antibiotics attack different bacteria, so it is important that specific bacteria should be treated by
specific antibiotics.
The use of antibiotics has greatly reduced deaths from infectious bacterial diseases.…read more


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