bio p2

• EVOLUTION

  (disadvantage)

  loss of biodiversity

  reduction in gene pool

  (advantage)

  evolution of new species

  opportunity for speciation
• FOSSILS

  fossils buried deep so hard to find

  fossils smaller so harder to find

  more likely to be destroyed by earthquakes / erosion

  oldest organisms were softbodied so most of the tissue decayed

  dating older fossils is hard
• improving human food security in the future

  • less land required (so) more space for crops (for humans)
  • less methane (from animals)
  • therefore less global warming
  • (therefore) less harmful effects of global warming on (human)
  • allow more meat (from cows etc) for humans
• retina sensitive to light

  impulse passes along (sensory) neurone

  (along) optic nerve
• link to biodiversity

  • deforestation

  • loss of habitat

  • consequence of loss of habitat eg (change in) migration

  • fertiliser run off polluting water

  • use of pesticide / insecticide / herbicide reduces insects / plants which damages food chains

  • more soil erosion
• link to atmospheric pollution

  • more carbon dioxide (from farm animals / machinery)

  • more methane (from cows)

  • climate change or global warming

  • example of impact on biodiversity • acid rain
• FOSSILS FORMED

  (snake is) covered in sediment / mud or sinks into the mud

  (then) the soft parts decay / are eaten

  bones / hard parts do not decay

  (so) minerals enter bones or bones are replaced by minerals
• extinction

  • changes to the environment
  • new predators
  • new diseases
  • new (more successful) competitors
  • catastrophic event
• carbon cycle for growth of new leaves

  (carbon compounds in) dead leaves are broken down by decomposers /bacteria

  photosynthesis uses carbon dioxide

  (microorganisms) respire

  (and) release carbon from the leaves as carbon dioxide

  plants take in the carbon dioxide released to use in photosynthesis to produce glucose

  use of carbon in growth:

  • glucose produced in photosynthesis is used to make amino acids / proteins / cellulose (which are) required for the growth of new leaves
• why people might selectively breed cats

  • so that they do not have specific genetic defects
  • to produce docile cats or so they are not aggressive
  • for aesthetic reasons
• inbreeding

  • more likely to pass on (recessive) disorders
  • more likely to be susceptible to diseases
• Explain how the cat has been produced using selective breeding

  • parents who produce the least Fel D1 are initially selected
  • parents with the desired characteristic are selected
  • the parents are bred together to produce offspring
  • offspring with the desired characteristics are selected and bred
  • repeated over many generations
  • care is taken to ensure cats are healthy and avoid possible problems associated with selective breeding
• Explain how the mutation could cause the enzyme not to work

  • (mutation) changes from C to T in the DNA code
  • there is a change in the three bases
  • (mutation) changes the amino acid
  • (this could) change the protein (so it) forms a different shape / changed active site
  • (therefore) the enzyme no longer fits the substrate / carbohydrat
• intensive farming dis

  • diseases spread more rapidly
  • over use of antibiotics
  • increased use of fossil fuels (to heat the barn)
• how does intensive farming increase the efficiency of food production

  • kept inside or in a temperature controlled environment
  • less energy / heat is lost in controlling body temperature
  • kept enclosed or in a restricted environment
  • less energy required for movement
  • so more energy is available for growth
  • less energy / heat is transferred to the environment
• Suggest what would happen in the body of a person with hyperthyroidism.

  • too much thyroxine is released into the blood
  • raises BMR
  • causing increase in formation of glycogen / lipids / proteins
  • or increase in rate of respiration
  • or increase in breakdown of excess protein
• FSH causes eggs to mature and stimulate ovaries to produce oestrogen

  LH stimulates the egg to be released
• • (missing a dose causes a) dip / drop in progesterone levels (therefore)
  • FSH is not inhibited anymore
  • (therefore) LH is not inhibited anymore
  • (and consequently) an egg is matured and released
• abiotic

  • water
  • oxygen / air (in soil)
  • • pH (of soil)
  • • minerals / ions
  • • temperature
• biotic

  • • food
  • • predators / consumers / carnivores
  • • disease / pathogens / bacteria / fungi
• • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• BINORMIAL NAME = GENUS + SPECIES
• Examples of conditions that need to be kept constant are:

  • BODY TEMPERATURE
  • BLOOD GLUCOSE LEVELS
  • WATER CONTENT
• • PITUITARY GLAND: Known as the 'MASTER GLAND,' it produces SEVERAL hormones that regulate body conditions. These hormones influences OTHER GLANDS to stimulate OTHER HORMONES to be released to bring about effects.
  • THYROID: Produces THYROXINE, which is crucial for regulating metabolism, heart rate, and temperature.
• BMR is regulated by THYROID-STIMULATING HORMONE (TSH) which is released by the PITUITARY GLAND.

  • When TSH is RELEASED, the thyroid gland RELEASES thyroxine.
  • When TSH is INHIBITED (stopped), the thyroid gland STOPS RELEASING thyroxine.
• • A stimulus affects a receptor (cell or organ that converts a stimulus into an electrical impulse)
  • A sensory neurone carries impulses from the receptor to the CNS (spinal cord)
  • Connector/relay neurone carries impulse slowly (because it has no myelin sheath) across the spinal cord
  • The motor neurone carries impulses from the CNS to the effector
  • The effector (either a muscle or a gland) carries out the response
• Gravitropism: a response in which a plant grows towards (positive) or away (negative) from gravity.

  • Auxins’ role in gravitropism:
  • Made in the shoot tip
  • Then, it diffuses through the plant from the shoot tip
  • Auxin is unequally distributed in response to light and gravity
  • Auxin stimulates cell elongation
• Phototropism: a response in which a plant grows towards (positive) or away (negative) from the direction light is coming.

  • Auxins’ role in phototropism:
  • If the sun shines on the right side of a plant’s shoot, auxins accumulate on the dark opposite left side.
  • Auxins accumulating makes cells on the left side grow faster than cells on the right.
  • When the left side of the shoot starts growing faster than the right side, the shoot will start to bend to the right side towards sunlight.
• • Population: a group of organisms of one species living in the same area at the same time.
  • Community: all of the populations of different species in an ecosystem.
  • Ecosystem: a unit containing the community of organisms and their environment interacting together.
• • Carbon is taken from the atmosphere by photosynthesis (plants)
  • It is passed on to animals and decomposers by feeding.
  • It is returned by respiration in plants and animals and decomposed by microorganisms.
• HUMAN INSULIN IN BACTERIA

  • Isolation of the DNA making up a human gene using restriction enzymes, forming sticky ends.
  • Cutting of bacterial plasmid DNA with the same restriction enzymes, forming complementary sticky ends.
  • Insertion of human DNA into bacterial plasmid DNA using DNA ligase to form a recombinant plasmid – insertion of the plasmid into bacteria.
  • Replication of bacteria containing recombinant plasmids, which make human protein as they express the gene