biology paper 2

• Osmosis

  movement of water across a partially permeable membrane from high to low concentration
• Preserving biodiversity

  breeding programmes, protecting habitats, reducing deforistation, reforistation
• Conservation

  preservation of ecosystems and organisms living in them
• eutrophication

  1. fertilizers added to field
  2. heavy rain washes it off
  3. nitrates and phosphates washed into stream
  4. this encourages algae to grow
  5. algae blocks sunlight and plants at bottom of the lake die
  6. animals die as plants arent producing oxygen
• Fish farming

  overfishing has damaged aquatic ecosystems

  aims to produce more fish

  fish farmed in large nets of tanks within lakes or sea

  can cause disease to spread easier, predators can be trapped in nets, fish can escape
• Parasitism

  lives in or on another organism, it takes what it needs and host recieves nothing
• Photosynthesis

  carbon dioxide+water=glucose+oxygen
• aerobic respiration

  glucose+oxygen=carbon dioxide+water
• biotic factors

  competition

  new pathogens

  new predators

  availability of food
• Abiotic factors

  light intensity

  carbon dioxide levels

  temperature

  moisture levels
• enzymes

  biological catalyst

  speeds up chemical reactions
• active transport

  movement of particle through a cell membrane from low to high concentration using energy
• diffusion

  movement of particles from high to low concentration
• synthesis

  building larger molecules from smaller subunits
• photosynthesis

  plants trap energy transferred by light with is then transferred into molecules of sugar

  occurs in chloroplasts - contain chlorophyll that traps light

  endothermic reaction
• leaf adaptations

  palaside cells - packed with chloroplasts

  stomata - allows carbon dioxide to diffuse

  guard cells - light = water flows in making them rigid = opens stomata

  night - water flows out losing rigidness = stomata shuts
• limiting factors - photosynthesis

  carbon dioxide concentration

  temperature

  light intensity
• root hair cell

  hairs = large surface area = more water and mineral ions absorbed

  thin cell walls = flow of water not slowed

  water passes into cytoplasm by osmosis
• transpiration

  flow of water into root up stem and out of leaves
• increase transpiration

  wind

  low humidity

  high temperatures

  greater light intensity
• xylem vessel

  form pipes leading from roots into leaves

  long empty vessel = water can move easily

  thick side walls , rings of hard lignin = water pressure doesnt burst / collapse them

  rigidness = helps support plant
• phloem


  sucrose translocated in sieve tube of phloem

  large central channel in sieve cell is connected to neighbor by holes

  companion cells = pump sucrose in + out of sieve cells that form sieve tubes

  sucrose pumped in = increased pressure = sucrose flows up to growing shoots / down to storage organs
• type 1 diabetes

  pancreatic cells destroyed by immune system so cant produce insulin
• type 2 diabetes

  cells dont produce enough insulin / target organs dont respond properly
• white blood cells

  lymphocytes = produce antibodies = stick to and destroys foreign bodies

  phagocytes = surround + digests foreign bodies
• platelets

  clots the blood
• heart rate

  number of times heart beats in a minute
• stroke volume

  volume of blood ejected from the heart each beat
• cardiac output

  volume of blood ejected per minute

  SV * HR