Biology 1

All topics needed for AQA GCSE B1

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Co-ordination and Control

  • Control of the body's functions and responses involves hormones (chemicals) and the nervous system (impulses- electrical at neurones, chemical at synapses).
  • Reflex actions are rapid and automatic, they do not involve the brain
  • Reflex Actions - stimulus->receptor -> co-ordinator ->effector ->response
  • Menstrual Cycle = 28 days, ovulation at day 14
  • FSH - made by pituarity gland, causes egg to mature and stimulates the oestrogen to be produced
  • OESTROGEN - prduced by ovaries, stimulates womb lining to develop to recieve the fertillised egg, inhibits production of FSH, stimulates production of LH
  • LH made by pituarity gland, stimulates the mature egg to be released
  • The contraceptive pill- contains oestrogen , prevents pregnancy
  • Fertillity treatment - FSH given
  • Internally controlled conditions are - water content, ion content, temperature and blood sugar levels
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Healthy Eating

  • Balenced diet = correct amouts of the different foods that the body needs
  • Malnourished = don't have this balanced diet
  • if you need more food than you need you put on weight
  • very fat = OBESE = more likely to suffer from arthiritus, diabetes, high blood pressure and heart disease.
  • Fast food often contains too much fat and salt
  • Too much salt can lead to high blood pressure
  • Cholesterol = made by the liver and is in the foods we eat. Too much =increased risk of heart disease and disease of the blood vessels
  • Low - density lipoproteins (LDL's) can cause disease
  • High - density lipoproteins (HDL's) are 'good' for you
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Drug abuse

  • All drugs can cause problems whether they are legal or illegal
  • Many drugs are addictive, if you try to stop taking them, this can cause severe withdrawal symptoms
  • Some legal drugs can be used illegally
  • Alcohol is a legal recreational drug which can cause serious health problems and slows down the nervous system therefore slows down your reactions
  • Smoking tobacco is legal over the age of 16. Niccotine is very addictive. Tobacco smoke can cause many health problems and will probably lead to an early death.
  • When new drugs are developed, they have to be tested thoroughly to ensure there are no serious side effects
  • Thalidomide was used as a sleeping pill which was discovered to prevent morning sickness in pregnant women. It had very serious side effects on feuteses in the womb . it is now used to help cure leprosy
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Contolling Infectious Disease

  • Pathogens are microorganisms that case infectious disease
  • Bacteria and viruses produces poisons (toxins)that make us feel ill.
  • White blood cells do 3 things 1. ingest pathogens. 2. Produce antiobodies. 3. Antibodies
  • Antibiotics can be used to kill bacteria
  • Viruses live in cells, so to kill the virus you have to kill/damage the cell
  • Pathogens can change by mutation or through natural selection. It is very hard to control these pathogens.
  • New medicines must be : effective, be able to be stored for a period of time and safe,
  • New medicines have to be tested thoroughly on animals and human volunteers to see if they work and to see if there are any serious side effects.
  • You can be immunised against a disease; you are given dead or inactive forms of the pathagen. The white blood cells react by producing antibodies. When the real pathogen comes along, the white blood cells respond rapidly and produce the correct antibody.
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Adaptation for Survival

  • If animals weren't adapted for survive in the areas they live in, they would die.
  • Plants compete for light, water and nutrients
  • Plants need to be adapted to survive being eaten by animals.
  • Successful plants have structures and habits that allow healthy growth.
  • Animals compete with each other for food, water, space, mates and breeding sites.
  • Most succesful animals survive, and pass on their genes to the next generation.
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  • Information from parents is passed to the offspring in the genes
  • 2 types of reproduction- sexual and asexual
  • sexual - involves fusion of sex cells (gametes). 2 parents. There is a mixing of genetic information = variation
  • asexual - only 1 parent, offspring identical to parent (a clone)
  • Cloning of plants - cuttings (cheap and effective)
  • - tissue culture (taking groups of cells and growing them)
  • Cloning of animals - embryo transplant (embryo's split into smaller groups of cells , then each group is allowed to develop in a host animal)
  • - fusion cell cloning
  • - adult cell cloning (nucleus of cell of animal you want is put into an empty egg cell. this cell is then developed in a different animal.
  • Genetic engineering involves changing the genetic make-up of an organism to ensure the organism have desired charachteristics
  • Genetic engineering is used to make insulin for diabetics.
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  • Fossils help to decide when life began on Earth
  • Therios of evolution - 1. Lamark 2. Darwin
  • Lamark - acquired charachteristics can be passed on to the next generation.
  • Darwin - takes place through natural selection. The best adapted survive to breed and pass on their genes
  • Sexual reproduction = variation.
  • Mutation means more variation and can help an animal/plant to survive and pass on the gene.
  • Extinction = a species which once existed has been completely wiped out
  • Extinction can be caused by: new disease, climate change, new predator, new competitor , habitat may be destroyed
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How people affect the planet

  • Human population increasing rapidly = more resources are being used and we produce more waste and polution
  • Acid Rain = caused by sulphur dioxide and nitrogen oxides
  • GLOBAL WARMING = inceases of greenhouse gases means less heat is able to escape the atmosphere, warming up the Earth
  • This is causing ice caps to melt and sea levels to rise.
  • These greenhouse gases are CO2 (from burning fuels and deforestation) and methane (from cows and rice fields)
  • Sustainable development means finding ways of reducing the need for more resources.
  • Lichens are indicators of the level of pollution in the air.
  • Freshwater invertabrates are indicators of pollution in freshwater
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