AQA Biology 1

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  • Created by: Joyce Jay
  • Created on: 18-12-12 17:34
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Keeping Healthy 1
A balanced diet keeps someone healthywithout it, someone is malnourished. Too much food can lead
to someone becoming overweight, and too little food can lead to someone becoming underweight.
Metabolic rate: rate of chemical reactions in cells, affected by daily activity, genes, gender, age.
Cholesterolgood: HDL. Bad: LDL. HDL cholesterol used for cell membranes and vital substances.
High LDL levels can lead to heart disease, type 2 diabetes, and cardiac arrest.
Pathogens are microbesbacteria or virus.
Pathogens can produce toxins to make you feel ill, though it is rarely done by virusesthey usually
invade cells, damaging them.
A doctor called Semmel weiss realised that infection could be transferred by direct contact, telling his
staff to wash their hands between dissecting a dead body and helping women give birth.
The skin helps stop pathogens entering the body.
Pathogens are also trapped by mucus and killed by stomach acid.
White blood cellsthey can ingest pathogens. They can produce antibodies to help destroy pathogens.
They can produce antitoxins to counteract the toxins that pathogens produce.
Coordination & Control 1
Receptors detect stimuli. Receptors are in the eye, ear, nose, tongue & skin.
Light stimulates receptors in eye so electrical impulses pass to the brain along neurons. Stimule
include: sounds, chemicals, temperature, touch, pain.
Brain + spinal cord= CNS.
Sensory neurons: receptors to CNS.
Motor CNS to effector organ (muscle/gland).
1. Receptor detects stimulus.
2. Sensory to CNS.
3. Relay passes on.
4. Motor neuron stimulated, passes to effector.
5. Action is taken. Does not go to the brain, so it's quicker.
Synapse Gap between 2 neuroneschemicals transmits impulse across.
Menstrual cycle: 1. FSHmade by pituitary gland matures an egg, oestrogen production.
2. Oestrogenmade by
Ovaries, inhibits FSH production, causes womb lining, LH production. 3. LH made by pituitary gland,
gets matured egg to be releasedovulation.
Contraceptive: have oestrogen or progesterone. Progesteroneonly pills: fewer side effects. Prevent
production of FSHno eggs mature

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Contraceptives: plan pregnancies, reduce family size, but can have side effects, is unethical, against
IVF FSH and LH injections. Eggs collected from woman, fertilised with man and become an
embryotransplanted into woman. Helps infertile couples. However, expensive and not always
Medicine & Drugs
Medicines are tested to check for safety, side effects and effectiveness.
Firstly, tested on cells & tissues or organstesting for safety.
Then on animalsinformation on doses and side effects.
Healthy human volunteersvery low doses to check for side effects.…read more

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Offspring get one set of chromosomes from mother, other set from father.
Asexual no fusion of gametes. All genetic information is from one parent little variety.
Sexual fusion of gametes. Mixing of genetic information, so offspring show variation.
Genes are most important in controlling the appearance of an individual.
Cloningplant cloning can be cheap and effective. Cuttings can be taken and then grown. Taking cells
from a plant and growing them under special conditions tissue culture is more expensive.…read more

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Homeostasis is maintaining a constant internal environment:
Conditions in your body need to be kept steady so that cells can function properly. This involves
balancing inputs (stuff going into your body) with outputs (stuff leaving). For example:
Levels of Co2 respiration constantly produces CO2, which you need to get rid of.
Water content you need to keep a balance between the water that you gain (in drinks,
foods, and from respiration) and the water you pee, sweat and breathe out.…read more


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