AQA Biology unit one - Keeping Healthy

1. AQA Biology Unit one
Keeping healthy

2. Diet and exercise
 Regular exercise and a balanced diet are needed to keep
the body healthy. Too little food leads to a person being
underweight and prone to certain types of illness, while
too much food and not enough exercise leads to a
person being overweight and other types of ill health.

3.  Nutrients
 A mixture of different types of food in the correct amounts is
needed to maintain health.
 The main food groups are carbohydrates, fats and
proteins.
 This table summarises some typical sources of these
nutrients and why our bodies need them.

4. Carbohydrates
potatoes, pasta, bread,
bananas, sugar and rice
a source of energy for life
processes
Fats
cheese, butter, margarine
and oils
a source of energy for life
processes: fats are also
needed to make cell
membranes and to
insulate our bodies
Proteins
meat, fish, eggs and
cheese
growth and repair -
building cells
Mineral ions and vitamins are also
important in a healthy diet. They are
needed in small amounts for healthy
functioning of the body.

5.  small amounts for healthy functioning of the body.
 Imbalanced diets
 An imbalanced diet causes a person to become malnourished.
For example:
 too little food may lead to a person being underweight
 too much food may lead to a person being overweight.
 A poor diet may also lead to deficiency diseases. For example,
too little vitamin D in the diet can lead to rickets, which affects
the proper growth of the skeleton. Type 2 diabetes is also a
problem related to poor diet. Note that you do not need to know
how the nutrients work or the effects of any particular deficiency
in the diet for your exam.

6.  Exercise
 If someone’s diet consists of food with a lower energy content than the
amount of energy their body uses, the person will lose body mass.
 Metabolic rate
 Respiration is a chemical reaction that allows cells to release energy
from food. The metabolic rate is the speed at which such chemical
reactions take place in the body and varies because of several factors,
including age, gender and inherited factors.
 Metabolic rate is also affected by the:
 proportion of muscle to fat in the body
 amount of exercise and other physical activity.
 The metabolic rate increases as we exercise and stays high for a while
afterwards. People who exercise regularly are usually healthier than
people who don't.

7.  Other factors affect health too, including inherited factors. For
example, the cholesterol level in the blood can affect health.
Cholesterol is made in the liver and is needed for healthy cell
membranes. However, too much cholesterol in the blood
increases the risk of heart disease and diseased arteries.

8. Quick Test Q1
 What is 'the metabolic rate'?
 A ) The speed at which our food is digested
 B) The speed at which chemical reactions take place in our
bodies
 C) The speed at which we eat

9. Q2
 After exercise: ?
 A) the metabolic rate stays permanently high
 B) the metabolic rate stays permanently low
 C) the metabolic rate stays high for a while

10. What is it best to have for a healthy heart?
A high proportion of HDL compared to LDL
A low proportion of HDL compared to LDL
A lot of cholesterol in the diet

11. Answers
 Q1 What is 'the metabolic rate'?
 The speed at which chemical reactions take place in our
bodies

12. Q2
 After exercise:
 the metabolic rate stays high for a while

13. Q3
 What is a feature of low-density lipoproteins (LDLs)?
 A feature of LDLs is they carry cholesterol from the liver to
the cells of the body.

14. Q4
 What is it best to have for a healthy heart?
 It is best to have a high proportion of HDL compared to LDL
for a healthy heart.