2018

• biotic factors

  -diseases

  -herbivores
• Abiotic factors


  -temp

  -water
• A square frame measuring 0.5m $\times$ 0.5m = Quadrat


  An electronic device to measure light intensity- Light meter
• to keep light intensity as similar as possible

  why is the investigation done as quickly as possible on the same day
• FACTOR-lack of water/rain


  REASON-because the leaves are stopping the rain.
• why are these microorganisms called extremophiles

  -they survive in high temperatures

  -They survive where it is acidic
• carl Woese

  developed the 3-domain system of classification
• 3 -domain system of classification


  -based on DNA evidence

  -archaea-simple bacteria

  -Prokaryota- true modern bacteria

  -Eukaryota -includes protists, fungi, plants & animals
• Why does a conscious action take longer than a reflex action

  The impulse has to travel to the brain and back
• suggest one advantage of using a progesterone patch rather than a progesterone oral contraceptive

  lower dose so fewer side effects
• describe the type of cell division that produces gametes

  -called meiosis

  -DNA replicates

  -2 divisions to form 4 cells
• Q: Explain why the students thought their hypothesis would be correct.[3 marks]

  A:

  • Leaves block light near the tree, so there is less light.
  • As you move outwards, there is more light available.
  • More light increases photosynthesis, which produces more glucose for growth.
• Most of the microorganisms from the caves were classified as belonging to the Archaea domain of the ‘three-domain system’.Suggest why.

  Answer:

  These microorganisms live in extreme conditions.
• What advice should be given to doctors to stop the spread of the new antibiotic-resistant Pseudomonas strain?(6 marks)

  Summary Answer:

  • Don’t prescribe antibiotics for mild infections – body can fight it.
  • Don’t prescribe for viruses (e.g., colds/flu) – antibiotics don’t work on them.
  • If prescribed, make sure patients finish the full course – stops bacteria surviving and becoming resistant.
  • Only prescribe if patient has that specific strain – to avoid encouraging resistance.

  Hospital hygiene advice:

  • Doctors/nurses should use alcohol handwash/disinfect wards to kill bacteria.
  • Isolate infected patients – to stop spreading the resistant bacteria.
• Q: Compare how information is transferred along a neurone vs across a synapse (gap P).

  A:

  • In a neurone: transferred as electrical impulse
  • Across synapse: transferred by chemical movement

  
• In the 1950s, India couldn’t grow enough rice for its growing population. Scientists at IRRI (International Rice Research Institute) began a selective breeding program using 10,000 rice varieties. In 1966, they developed IR8 – a rice variety with short stems and large grains, yielding up to 10× more than traditional types. IR8 was grown widely across India to help feed the population.

  Answer to the Question – How IR8 was made using selective breeding (4 marks):

  Scientists:

  • Chose rice plants with short stems and large grains
  • Cross-bred the selected plants
  • Selected offspring with desired traits (shortest stems and largest grains)
  • Repeated the process over generations until all plants had these characteristics
• Why do some people agree and some disagree with growing genetically modified (GM) rice in India?

  Answer (4 marks):

  Agree:

  • GM rice is resistant to disease, leading to higher crop yield.
  • It can have better nutritional content (like added vitamins), improving people's health.
  • Resistant to herbicides, so less competition from weeds, meaning more water and nutrients go to the rice.

  Disagree:

  • Traditional rice varieties may be lost, causing reduced biodiversity.
  • GM rice might affect human health as there's not enough research yet.
  • Herbicide use may harm other plants, further reducing biodiversity.
• Describe the sequence of hormone interactions in the menstrual cycle and state where each hormone is produced.[5 marks]

  Answer:

  • FSH (from the pituitary gland) stimulates oestrogen production in the ovaries.
  • Oestrogen causes thickening of the uterus lining (especially during the first half of the cycle).
  • Oestrogen inhibits FSH but stimulates LH release from the pituitary gland.
  • A high level of LH triggers ovulation (egg release around day 14).
  • Progesterone (from the ovaries) inhibits both FSH and LH to prevent another egg being released.
• Why can't triploid oysters reproduce?

  [1 mark]

  • Meiosis doesn’t work properly because the chromosome number can’t halve evenly with three sets.
• Why do triploid oysters grow more quickly than diploid oysters?

  [2 marks]

  • They don’t use energy for reproduction,
  • So more energy is available to synthesise proteins and support growth.
• Q7.5 — Reasons for population reduction (2 marks)

  1. New predators may be eating the oysters.
  2. New pathogens could be causing diseases
• Q7.6 — Evaluate the production of triploid oysters (6 marks)

  For:

  • Oysters available all year → more popularity + reliable supply.
  • Cheaper to produce → helps feed growing population.
  • Faster growth → more oysters for restaurants / supermarkets = more profit.
  • Replenished yearly → more sustainable.
  • Consistent harvest = stable income for farmers.

  Against:

  • Chemical used (cytochalasin B) is a carcinogen (cancer risk).
  • Triploids might outcompete native oysters → harm ecosystem / cause extinction.
  • People may avoid eating them due to chemical use.
  • Farmers need to buy seed oysters each time → increased cost.

  Other points:

  • Should fully test oysters before sale.
  • Need alternatives to make triploid oysters.
  • Uncertain impact on environment / ecosystem.
  • Might change flavour or replace natural beds.