AQA Biology New Specification

AQA Biology New Specification

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3.3 Unit 1: Biology 1
B1.1 Keeping healthy
A combination of a balanced diet and regular exercise is needed to help keep the body healthy. Our
bodies
provide an excellent environment for many microbes which can make us ill once they are inside us. Our
bodies
need to stop most microbes getting in and deal with any microbes which do get in. Vaccination can be
used to
prevent infection.
Candidates should use their skills, knowledge
and understanding to:
evaluate information about the effect of food
on health
evaluate information about the effect of lifestyle
on development of disease
analyse and evaluate claims made by slimming
programmes, and slimming products.
B1.1.1 Diet and exercise
a) A healthy diet contains the right balance of the
different foods you need and the right amount of
energy. Carbohydrates, fats and proteins are used
by the body to release energy and to build cells.
Mineral ions and vitamins are needed in small
amounts for healthy functioning of the body.
A person is malnourished if their diet is not
balanced. This may lead to a person being
overweight or underweight. An unbalanced
diet may also lead to deficiency diseases or
conditions such as Type 2 diabetes.
b) A person loses mass when the energy content
of the food taken in is less than the amount of
energy expended by the body. Exercise increases
the amount of energy expended by the body.
c) 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. Metabolic
rate may be affected by inherited factors.
d) Inherited factors also affect our health; for example
cholesterol level.
e) People who exercise regularly are usually
healthier than people who take little exercise.
B1.1.2 How our bodies defend themselves against infectious diseases
Candidates should use their skills, knowledge
and understanding to:
relate the contribution of Semmelweiss in
controlling infection to solving modern problems
with the spread of infection in hospitals
explain how the treatment of disease has changed
as a result of increased understanding of the action
of antibiotics and immunity
evaluate the consequences of mutations of bacteria
and viruses in relation to epidemics and pandemics
evaluate the advantages and disadvantages of

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Microorganisms that cause infectious disease
are called pathogens.
b) Bacteria and viruses may reproduce rapidly inside
the body and may produce poisons (toxins) that
make us feel ill. Viruses damage the cells in which
they reproduce.
c) The body has different ways of protecting itself
against pathogens.
d) White blood cells help to defend against pathogens by:
ingesting pathogens
producing antibodies, which destroy particular
bacteria or viruses
producing antitoxins, which counteract the toxins
released by the pathogens.…read more

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Many strains of bacteria, including MRSA, have
developed resistance to antibiotics as a result of
natural selection. To prevent further resistance
arising it is important to avoid overuse of antibiotics.
j) Mutations of pathogens produce new strains.
Antibiotics and vaccinations may no longer be
effective against a new resistant strain of the
pathogen. The new strain will then spread rapidly
because people are not immune to it and there is
no effective treatment.…read more

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Hormones are used in some forms of contraception and in fertility
treatments. Plants
also produce hormones and respond to external stimuli.
Candidates should use their skills, knowledge
and understanding to:
evaluate the benefits of, and the problems that may
arise from, the use of hormones to control fertility,
including In Vitro Fertilisation (IVF)
evaluate the use of plant hormones in horticulture as
weedkillers and to encourage the rooting of
plant cuttings.
15
Subject Content16
B1.2.…read more

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The fertilised
eggs develop into embryos. At the stage when
they are tiny balls of cells, one or two embryos
are inserted into the mother's uterus (womb).
Additional guida
B1.2.3 Control in plants
a) Plants are sensitive to light, moisture and gravity:
their shoots grow towards light and against the
force of gravity
their roots grow towards moisture and in the
direction of the force of gravity.
b) Plants produce hormones to coordinate and
control growth. Auxin controls phototropism
and gravitropism (geotropism).…read more

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Drugs are tested in a series of stages to find
out if they are safe and effective.
New drugs are extensively tested for toxicity,
efficacy and dose:
in the laboratory, using cells, tissues and
live animals
in clinical trials involving healthy volunteers
and patients. Very low doses of the drug are
given at the start of the clinical trial. If the drug is
found to be safe, further clinical trials are carried
out to find the optimum dose for the drug.…read more

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Awareness of the benefits of medical drugs, the impact
of non-medical drugs such as alcohol and the possible
misuse of legal drugs should be considered.
Additional guidance:
B1.4 Interdependence and adaptation
Organisms are well adapted to survive in their normal environment. Population size depends on a
variety of factors
including competition, predation, disease and human influences. Changes in the environment may
affect the
distribution and behaviour of organisms.…read more

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Plants may be adapted to survive in dry environments
by means of:
changes to surface area, particularly of the leaves
water-storage tissues
extensive root systems.
g) Animals and plants may be adapted to cope with specific
features of their environment, eg thorns, poisons and
warning colours to deter predators.
B1.4.2 Environmental change
a) Changes in the environment affect the distribution
of living organisms.
b) Animals and plants are subjected to environmental
changes.…read more

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Radiation from the Sun is the source of energy for
most communities of living organisms. Green plants
and algae absorb a small amount of the light that
reaches them. The transfer from light energy to
chemical energy occurs during photosynthesis.
This energy is stored in the substances that make
up the cells of the plants.
b) The mass of living material (biomass) at each stage
in a food chain is less than it was at the previous
stage.…read more

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