biology section 7/8/9

• what are hormones 


  chemicals released by glands and are carried in blood to other parts of body (endocrine glands which make up endocrine system)
• what are the endocrine glands

  pituitary gland: release hormones and act on other glands

  ovaries: produce oestrogen

  testes: produce testosterone

  thyroid gland: produces thyroxine which regulates heart rate & temp

  adrenal glands: produce adrenaline

  pancreas: produces insulin to control blood glucose level
• what is oestrogen 


  causes lining of uterus to thicken and grow and which causes ovulation
• what is progesterone

  released by corpus luteum after ovulation and maintains lining of uterus & prevents release of hormones which causes egg dev & ovulation
• what is homeostasis 


  keeping the right conditions inside body so everything works properly e.g amount of glucose
• what does insulin do

  converts glucose into glycogen which is stored in liver & muscle cells, removes glucose from blood
• what is type 1 diabetes

  pancreas stop making insulin, need insulin injected
• what is type 2 diabetes

  resistant to insulin and if pancreas don’t produce enough insulin, can be controlled by healthy diet, exercise
• what do organisms take in & out 


  take in oxygen, water, food, mineral ions

  get rid of carbon dioxide & urea (waste product of protein breakdown in animals)
• what does the alveoli do

  moist lining for dissolving gases, very thin walls and good blood supply to make them adapted to gas exchange in mammals
• words to know for relationships between living things

  habitat: place where organism lives

  community: different species living in a habitat

  ecosystem: community of organisms with non-living condition
• what is interdependent 


  organisms depend on each other for things like good and shelter
• what is mutualism 


  type of relationship between two organisms e.g bees and flowering plants
• what are abiotic and biotic factors

  abiotic: non-living factors e.g temperature

  biotic: living things e.g predation

  both affect distribution of population and population size
• abiotic factors

  light intensity: as trees grow, they can shade the grass

  amount of water: daisies grow best when soils are slightly wet

  temperature: organisms prefer warmer temps

  level of pollutant: lichen can’t survive if concentration of sulphur dioxide is too high
• biotic factors

  competition: red and grey squirrels live in same habitat and compete for food & shelter

  predation: foxes are predators and rabbits are their prey
• how can you find population size of small organisms

  quadrat
• what can belt transects be used for 


  study the distribution along a gradient
• what is biodiversity 


  variety of living organisms in an ecosystem
• what affects biodiversity 


  species in area decreasing means biodiversity will decrease

  species in area increasing means biodiversity will increase

  humans can have a positive effect from reforestation
• what can reduce biodiversity 


  eutrophication: nitrates used as fertilisers, can get into river and lakes from rain and cause death of species in water

  fish farms: fish can be farmed in big tents, fish food can got into water an cause eutrophication, parasites can infect fish and infect wild animals

  predators e.g sea lions can die as they are attached to nets
• how can non indigenous species reduce biodiversity 


  species that aren’t naturally found in area and brought there could kill other species e.g signal crayfish carry a disease that kill UK crayfish
• carbon cycle

  plants take in co2 from air during photosynthesis

  these make carbon compounds like carbohydrates

  eating passes carbon compounds in plant to animals in food chains

  plant & animal respiration releases co2 in air

  they eventually die and are turned into useful products

  burning plant & animal products & fossil fuels release co2 back in air

  decomposers break animal waste and dead organisms and this releases co2 back in air through respiration
• water cycle

  energy from sun makes water evaporate and turn into water vapour

  water also evaporates from plants

  warm water vapour is carried upwards

  water vapour cools and condenses to form clouds

  water from clouds fall as precipitation

  water drains into sea and process repeats
• nitrogen cycle

  nitrogen fixing bacteria: takes nitrogen gas and turn it into ammonia

  nitrifying bacteria: turn ammonia into nitrites then nitrates, these can be taken by plants

  plants use nitrates to make proteins

  animals take nitrogen when they eat plants

  bacteria working as decomposers break down dead plant & animals which releases ammonia

  denitrifying bacteria turn nitrates back into nitrogen gas
• how can farmers increase nitrates in soil 


  crop rotation: nitrogen fixing crop has nitrogen fixing bacteria in roots which can put nitrates into soil

  fertilisers: artificial fertilisers contain nitrates but are expensive, animal manure or compost put nitrogen into soil when they decompose
• how can farmers increase nitrates in soil 


  crop rotation: nitrogen fixing crop has nitrogen fixing bacteria in roots which can put nitrates into soil

  fertilisers: artificial fertilisers contain nitrates but are expensive, animal manure or compost put nitrogen into soil when they decompose