Biology Paper 1

• natural contraception

  • abstinence
  • rhythm method - avoid sex around ovulation
• surgical contraception

  • vasectomy - sperm tubes cut and tied
  • female sterilization - oviducts cut and tied
• auxins - plant hormones

  • selective weed killer
  • delay fruit ripening
  • seed dormancy
• ethene

  • ripening of fruit
  • flowering
• giberellins

  • seed dormancy
• parthenocarpy

  • seedless fruit
• type 1 diabetes

  • childhood
  • treatment - insulin injections
  • problem - can't produce insulin
• type 2 diabetes

  • later in life
  • treatment - regulate diet
  • problem - no response to insulin
• urine to detect problems

  • blood - diseases in kidney, urinating system or bladder
  • sugar - diabetes
  • protein - kidney disease
• haemodialysis

  • blood is diverted to an external machine to be filtered
• hypertonic

  • lots of sugars/salts
• isotonic

  • same concentration as cells
• hypotonic

  • very dilute
• reflex arc

  • stimulus --> sensory receptors detect --> impulses get to CNS (coordinates response) --> impulse goes to effectors --> response
• accomodation


  far object - stretch lens

  close object - fatten lens
• rod and cones


  rod cells - light intensity

  cone cells - colours
• Adrenaline?


  increased heart rate --> more blood + oxygen delivered

  increased rate and depth of breathing --> cope with demand for more oxygen

  diverted blood from gut to muscles --> muscles have more glucose + oxygen

  glucose released from liver --> increased respiration

  pupils dilate --> more light --> better vision

  hair stands up --> appear larger, more threatening
• mechanical contraception

  • IUD/IUS (intra-uterus device/system)/coil - no sperm in uterus
  • diaphragm/ cap - no sperm in uterus
  • condom - no sperm in vagina
• chemical contraception

  • oral contraceptive pill (taken daily) - oestrogen and progesterone --> inhibits FSH --> no mature egg
  • implant/ injection --> slow release hormone over 3 years
  • spermicides (cream inserted into vagina) - normally used with diaphragm
• small intestine (SI)

  • digests food
  • walls of SI have villi and micro villi --> larger surface area
• xylem

  • made of dead cells, thick walls, lignin, impermeable
  • water and minerals one direction
• phloem

  • made of living cells, thin walls, sieve plates + cytoplasm
  • sugar and amino acids two direction
• arteries

  • high pressure
  • thick outer wall
  • thick muscle and fibre
  • small lumen
• veins

  • valves, goes to the heart
  • thin wall, thin muscle and fibre
  • large lumen
• capillaries

  • semi permeable
  • connect arteries and veins
  • single cell thick wall
  • small lumen
• test for reducing sugars

  • reagent - Benedict's
  • method - add reagent to food sample and boil in water bath
  • initial colour - blue
  • colour change - brick red precipitate
• test for starch

  • reagent - iodine
  • method - add to the food
  • initial colour - yellow/brown
  • colour change - blue/black
• test for protein 


  reagent - biuret (NAOH + CuSO4)

  method - add to the food

  initial colour - blue

  colour change - lilac/purple
• test for fats 


  reagent - ethanol

  method - add to food and dissolve in water

  initial colour - colourless

  colour change - white emulsion
• ADH (anti-diuretic hormone)

  • released from the pituitary gland
  • increases reabsorption in the kidney
• eye

  retina - where the image form

  optic nerve - sends impulse to the brain

  lens - focuses light onto the retina

  suspensory ligament - connects cilliary muscle to lens

  cilliary muscle - alters the lens shape

  iris - alters pupil size to allow light

  pupil - allows light in to eye

  cornea - direct light into the eye