B1 OCR

B1 OCR

Diet and Exersize
1. Blood pressure has 2 readings: diastolic and systolic, in mmHg
  1. Smoking, a high alcohol intake and a diet rich in saturated fats and salt increase blood pressure
    1. High blood pressure can damage the brain (stroke) and kidneys
2. Being fit is the ability to do exersize, being healthy is being free from disease
3. A balanced diet will vary according to age, gender, activity, religion or personal choice
Drugs and Disease
1. Harmful drugs are classified as class A, B and C. Class A being the most harmful
  1. Depressant and stimulant drugs affect the nervous system by affecting the transmission across synapses
    1. High levels of alcohol can cause cirrhosis of the liver
2. Immunisation protects against certain diseases by using harmless pathogens
3. Changes in the lifestyle can reduce the risk of certain cancers
4. The mosquito is the vector that carries malaria
  1. Plasmodium is the pathogen that causes malaria. It is a parasite and humans are its host
Homeostatis and Plant Hormones
1. Homeostatis is maintaining a constant internal environment
2. Vasodilation and vasconstriction control heat transfer from the body
  1. Auxins are involved in phototropism (response to light) and geotropism (response to gravity)
    1. A spinal reflex involves a receptor, sensory, relay and motor neurones and an effector
3. Auxins are a group of plant hormones. They cause shoot curvature by cell elongation
  1. The hormone insulin controls blood sugar levels. It converts excess blood glucose into glycogen
    1. Automatic systems in the body keep water, temperature and carbon dioxide levels constant
The Nervous System
1. Light rays are refracted as they pass through the corneas and lens
2. Monocular vision has a wider field of view but poorer distance judgement than binocular vision
  1. Long and short sight is caused by the eyeball or lens being the wrong shape
  2. The eye accommodates by altering the shape of the lens
3. A nerve impulse travels along the axon of a neurone
  1. A neurotransmitter substance diffuses across a synapse, so the nerve impulse can pass to the next neurone
    1. A spinal reflex involves a receptor, relay, sensory and motor neurone and an effector
Variation and Inheritance
1. Inherited disorders are cause by faulty alleles
  1. Most faulty alleles are recessive
2. Dominant alleles are expressed if present, recessive alleles are expressed in the absence of a dominant allele
  1. Alleles are different versions of the same gene
3. Being homozygous is having 2 identical alleles, being heterozygous is having two different alleles
4. Human body cells have 23 pairs of chromasomes
  1. Sex is determined by sex chromosomes, XX in female, XY in male

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	Created by Hannah Fowkes almost 11 years ago