Population Viability Analysis: reading answers and analysis
Population viability analysis predicts how likely a species is to die out in an area, and it could guide Australian forestry decisions. Four processes drive extinction: random births and deaths in small populations, inbreeding, lost genetic variation, and environmental swings and catastrophes. Isolated groups are more vulnerable, and more logging always means a higher chance of extinction.
Questions 28-39 · 12 marks · 4 question blocks
Where the answers sit
YES / NO / NOT GIVEN (28-31) is Part A only. The process matching (32-35) is Part B, paragraphs A to D. The sentences (36-38) are Part C. Question 39 is about the whole passage.
Questions 28-31
Forestry's impact on wildlife is exactly what PVA assesses (YES). PVA has been used in the US and has 'enormous potential' in Australia, so it isn't long-established there (NO). A species is extinct when the last one dies, not when one is left (NO). Whether extinction is natural isn't discussed.
| Question | Answer | Also accepted |
|---|---|---|
| 28 | YES | — |
| 29 | NO | — |
| 30 | NO | — |
| 31 | NOT GIVEN | — |
Questions 32-35
A: the chance nature of reproduction. B: inbreeding when one sex is scarce (an imbalance of the sexes). C: lost genetic variation, so a species can't adapt. D: catastrophes like fire, flood and drought (natural disasters). 'Human disasters' and 'evolution' are the leftovers.
| Question | Answer | Also accepted |
|---|---|---|
| 32 | vi | — |
| 33 | iii | — |
| 34 | i | — |
| 35 | ii | — |
Questions 36-38
Part C says small isolated groups may not survive, that distribution matters as well as size, and that extinction becomes more likely when logging takes place. The key accepts several forms of each.
| Question | Answer | Also accepted |
|---|---|---|
| 36 | will not survive | may not survive / will become extinct / may become extinct / could become extinct |
| 37 | locality | distribution |
| 38 | logging takes place | logging occurs |
Question 39
The passage explains what PVA considers (chance, inbreeding, genetics, catastrophes, distribution) when assessing a species' chance of survival. It doesn't propose protection measures or economics.
| Question | Answer | Also accepted |
|---|---|---|
| 39 | B | — |
The questions most people get wrong
iii. B's example is 20 animals with only one male, an imbalance of the sexes that forces inbreeding.
NO. PVA was used successfully in the US, and there is now 'enormous potential' for Australia, so it's new there.
NO. 'A species becomes extinct when the last individual dies', so with one individual left it isn't yet extinct.
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Cambridge IELTS 1, Test 4, Reading Passage 3. The passage name belongs to Cambridge University Press. No passage text or question wording is reproduced on this page. The answers are published for self-marking, and the analysis is our own.