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A2 · Practice questions · Extinction and conservation

Threat, value, protection.

Six original Cambridge-style questions on why species become extinct and how they are conserved, locally and internationally.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Explain the threat, name the tool.

01
Explain
[4 marks]

Explain how climate change and the degradation of habitats can each cause a species to become extinct.

  • Climate change: temperature and rainfall patterns shift, so the conditions the species is adapted to are found in a smaller area or elsewhere. ✓
  • If the species cannot migrate or adapt quickly enough, survival and reproduction fall and the population declines. ✓
  • Habitat degradation / loss: clearing or pollution removes food, shelter and breeding sites, lowering the number of individuals the area can support. ✓
  • Fragmentation leaves small isolated populations with low genetic diversity, vulnerable to inbreeding and chance events. ✓
02
Recall
[3 marks]

Outline three reasons for the need to maintain biodiversity.

  • Ecological: diverse ecosystems are more stable and provide services such as pollination, nutrient cycling and clean water. ✓
  • Economic / practical: wild species provide food, medicines, timber and genes for improving crops and livestock; ecotourism brings income. ✓
  • Ethical / aesthetic: people have a responsibility to protect other species for their own sake and for future generations. ✓
03
Explain
[3 marks]

Outline the roles of frozen zoos and seed banks in the conservation of endangered species.

  • Frozen zoos store sperm, eggs, embryos and tissue samples in liquid nitrogen at −196 °C. ✓
  • These keep genetic diversity and can be used in IVF / embryo transfer, even after the donor has died. ✓
  • Seed banks store dried seeds at low temperature (about −20 °C) for long periods, conserving the genetic diversity of wild plants and crops; seeds are germinated periodically to test viability and renew stocks. ✓
04
Explain
[4 marks]

Describe how IVF, embryo transfer and surrogacy can be used to increase the number of offspring of an endangered mammal.

  • A female of the endangered species is treated with hormones so that several eggs mature; the eggs are collected. ✓
  • The eggs are fertilised with sperm (fresh or from a frozen zoo) in the laboratory: IVF. ✓
  • The embryos are grown for a few days, then transferred into the uterus of a female: embryo transfer; spare embryos can be frozen. ✓
  • A surrogate mother, possibly of a closely related common species, carries the pregnancy, so the rare female can produce many more offspring. ✓
05
Explain
[3 marks]

Explain reasons for controlling invasive alien species.

  • Invasive species often have no natural predators, parasites or competitors in their new area, so their populations increase rapidly. ✓
  • They out-compete native species for food, light or space, prey on them, or spread disease / hybridise with them. ✓
  • This reduces native biodiversity and can disrupt food webs and ecosystems (and damage crops or the economy), so controlling them protects native species. ✓
06
Recall
[2 marks]

Outline the roles of the IUCN and CITES in conservation.

  • IUCN: assesses the conservation status of species and publishes the Red List of threatened species, helping set priorities and supporting conservation projects. ✓
  • CITES: an international agreement that bans trade in the most endangered species and controls trade in others by permits (for example ivory, rhino horn, live animals and plants). ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.