B1: Diet and exercise
- Blood pressure has two readings, dialostic: blood pressure between heart beats. Systolic: maximum pressure the heart produces (both in mmHg, millimetres of mercury).
- Smoking, a high alcohol intake and a diet rich in saturated fats and salt increase blood pressure.
- High blood pressure can damage the brain (stroke) and the kidneys.
- Being fit is the ability to do exercise, being healthy is being fit from disease.
- A balanced diet will vary according to age, gender, activity, religion and personal choice.
- The body mass index (BMI) can be used to indicate being over or underweight.
- The EAR can be used to calculate protein requirements. It depends on age pregnancy and lactation.
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B1: Drugs and disease
- Harmful drugs are classified as Class A, B and C, Class A being the most harmful.
- Depressant and stimulant drugs affect the nervous system by affecting the transmission across synapses.
- High levels of alcohol can cause cirrhosis of the liver.
- Immunisation protects against certain diseases by using harmless pathogens.
- Changes in lifestyle can reduce the risk of some cancers.
- The mosquito is a vector that carries malaria.
- Plasmodium is the pathogen that causes malaria. It is a parasite and humans are its host.
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B1: Homeostasis and plant hormones
- Homeostasis is maintaining a constant internal environment.
- Vasodilation and vasconstriction control heat transfer from the body.
- Automatic systems in the body keep water, temperature and carbon dioxide levels constant.
- The hormone insulin controls blood sugar levels. It converts excess blood glucose into glycogen.
- Auxins are a group of plant hormones. They cause shoot curvature by cell elongation.
- Auxins are involved in phototropism (response to light) and geotropism (response to gravity).
- Plant hormones have many commercial uses (selective weedkiller, rooting powder, control of fruit ripening).
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B1: The nervous system
- Light rays are refracted as they pass through the cornea and lens.
- The eye acommodates by altering the shape of the lens.
- Long and short sight is caused by the the eyeball or lens being the wrong shape.
- Monocular vision has a wider field of view but poorer distance judgement than binocular vision.
- A nerve impulse travels along the axon of a neurone.
- A neurotransmitter substance diffuses across a synapse, so the nerve impulse can pass to the next neurone.
- A spinal reflex involves a receptor, sensory, relay and motor neurones and an effector.
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B1: Variation and inheritance
- Alleles are different versions of the same genes.
- Sex is determined by Sex chromosomes, ** in female, XY in male.
- Human body cells have 23 pairs of chromosomes.
- Dominant alleles are expressed if present, recessive alleles are expressed in the absence of a dominant allele.
- Being homozygous is having two identical alleles,being heterozygous is having two different alleles.
- Most faulty alleles are recessive.
- Inherited disorders are caused by faulty alleles.
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