recall mark schemes

• body temp regulation (6 marks)

  • temp receptors in TC detects blood temperature
  • temp receptors in the skin send impulses to TC giving info about skin temp
  • if its too high, vasodilation happens so more blood flows to the skin and more heat is lost
  • sweat glands release more sweat to cool the body by evaporation
  • if its too low, vasoconstriction happens so less blood flows to the skin and less heat is lost
  • muscles shiver to release heat energy from respiration
• darwin's theory

  • there is variation in the population
  • animals most adapted to the environment are more likely to survive and reproduce
  • they pass on these characteristics to their offspring
• blood glucose levels

  • if it's too high, insulin is released from pancreas
  • so glucose is moved into cells
  • if it's too low, glucagon is released
  • which causes glycogen to be turned into glucose and to be released into the blood
• how are amino acids removed from the body

  • amino acids are broken down and form urea in the liver
  • urea is filtered by kidney
  • and stored in the bladder
• water content in blood

  • if water is too low, ADH is released by pituitary gland into the blood
  • kidney reabsorbs more water
  • so more concentrated urine is produced
  • if water is too high, ADH is lowered
  • kidney reabsorbs less water
  • so more dilute urine is produced
• urine production

  • the kidney filters the blood
  • then reabsorbs all of the glucose
  • reabsorbs some of the ions
  • reabsorbs some of the water
  • releases urea
• genetic modification

  • use an enzyme to cut out the gene
  • use another enzyme to fuse it to the chromosome of the organism
  • at an early stage of development
• speciation

  • a population of a species is geographically isolated
  • there is genetic variation in the populations
  • the most adapted to environment survive and reproduce
  • over a long period of time the populations become genetically different and cannot breed a fertile offspring