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AQA GCSE Science ­
Biology Unit 1…read more

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1A…read more

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Diet and exercise
· Chemical reactions collectively known · THYROXINE made in THYROID
as METABOLISM GLAND touches every cell + controls
· Metabolic rate: how quickly chemical metabolic rate.
reactions take place · MORE THYROXINE = HIGHER
· Factors that affect your metabolic rate:
· The amount of activity you do · Muscles make energy to contract while
· The proportion of muscle to fat in your exercising more exercise = more
body muscle contraction more energy is
needed muscle cells respire to
· Inherited characteristics
release energy from glucose
glucose is provided by eating more
· Humans are made up of lots of cells, food.
cells all have to make energy
· Tall = bigger surface area lose more
· More muscle + less fat = higher heat, so cells respire to make heat
metabolic rate so high metabolic rate.
· Less muscle + more fat = lower · Overweight = high body mass, means
metabolic rate more energy needed to carry around
mass = high metabolic rate.…read more

Slide 4

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Diet, exercise and weight loss
· How does a diet of exercise, and · Four ways regular exercise improves
reduced sugar and fat result in weight your health:
loss? · You are rarely overweight
· Usually healthier then people who
· Exercise uses muscles which have to have little exercise
contract muscles must respire (make · You don't have the health risks
energy from glucose), during the process involved with being over weight
of respiring, muscle make more energy
· Exercise burns fat and raises
and burn fat therefore you lose
metabolic rate.
· Eating less fat and sugar means the
glucose your cells use to respire is taken
from the fat stored in your body this
makes you lose weight as you are using
up the fat stores in your body.
· With less fuel and more demand, you
use your reserves therefore you lose
weight…read more

Slide 5

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Diet and health
Food/nutrient Why you need Source Balanced diet:
to eat A balanced diet is compromised of
Carbohydrates For energy Pasta, potatoes, correct amounts of each food.
(immediate bread, rice
source) Malnutrition:
Fats For energy Fish, cake · If diet is unbalanced and the wrong
(store) amount or types of food are eaten.
· May lead to being too fat or thin
Proteins To build cells Fish, meat, eggs,
and repair tissue dairy products · Can also cause deficiency diseases,
such as, rickets.
Mineral ions and Needed in small Fresh fruit and
vitamins amounts to keep vegetables, dairy
the body products, liver
·Lack of vitamins or minerals:
functioning · Deficiency diseases
healthily · Lack of calcium = bones not strong
Roughage Prevents Unprocessed
enough tends to cause bowing and
constipation plant fruit bending of legs (sign of rickets)
·Lack of vitamin D = rickets
Water To keep Any drink
·Lack of vitamin C = scurvy (wounds
reactions going take long to heal, gums bleed, teeth go
loose and fall out, can eventually kill)…read more

Slide 6

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· Cholesterol · SUMMARY
· A fatty substance found in foods · Diet is very important for health
from animals · The correct amount of food
· Too much can cause CHD (coronary chemicals is needed to stay healthy
heart disease) which blocks arteries and the correct weight
and restricts blood flow · Too little of something can lead to
· However cholesterol is needed to deficiencies
stick cells together and is also used · Too much can cause weight problems
to make some hormones
· The liver makes cholesterol,
cholesterol can be reduced by
controlling how much the lover
makes ­ medicines called statins do
this effectively.…read more

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