Biology unit 1

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  • Created by: leah
  • Created on: 30-05-13 15:12

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, XX 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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