Biology unit 1

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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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.

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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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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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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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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