Answer Explanation: Academic Reading 1 - Population Viability Analysis

Answer Explanation: Academic Reading 1 - Population Viability Analysis

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Answer explanations to Academic Reading Passage Sample 1 - Population Viability Analysis.

Go to the Reading Passage using the link - Population Viability Analysis.

Answer Explanation:

Question 1: Scientists are interested in the effect of forestry on native animals.
Answer: Not Given.

Explanation: Some of the teachers we have talked to firmly disagree that the answer to this question is "Yes". They believe that the answer is clearly "Not Given". We agree with their arguments as they are strongly opposing the idea or assuming in IELTS Reading Test.

[Our previous answer was YES, but we've changed the answer to "Not Given".]

Answer Explanation: The reading text does not clearly mention anywhere that Scientists are interested in the effect of forestry on native animals. Since this is not explicitly mentioned, and we are not going to just assume; so, the answer is clearly "Not Given". 

Explanation in support of the answer "Yes": [We no longer believe that the answer is "Yes".]

This is perhaps the most confusing question in this whole reading passage. The techniques and strategies that you have learned so far (so did we) to find answers from a reading passage would easily assist you to decide that the right answer is 'Not Given'. Believe me, this was my initial answer as well. However, the right answer is 'Yes'. But why?

The first point to notice is that you have to find evidence for the answer from Part A, as mentioned in the reading passage. So even if any evidence is given otherwise in Part B or C, would not be applicable here. If you are still confused, read the question instruction again, which says 'Do the following statements agree with the views of the writer in Part A of Reading Passage 1?'.

Now we only have to search the proof within Part A of the paragraph and that has become a bit easier for us.

Look at the beginning of "Part A" that says:

"To make political decisions about the extent and type of forestry in a region it is important to understand the consequences of those decisions. One tool for assessing the impact of forestry on the ecosystem is population viability analysis (PVA).This is a tool for predicting the probability that a species will become extinct in a particular region over a specific period."

It is certain that someone is interested in the effect of forestry on native animals but we are still not convinced if this "someone" is a scientist or not?

Don't be confused about the word 'political' as it does not mean that here only politicians are involved. In this reading passage 'to make political decisions' indicates the 'decision-making process' and the writer implies that the decision-making process leads directly to consequences.
 
Part A of the reading passage includes:

"One tool for assessing the impact of forestry on the ecosystem is population viability analysis (PVA)." So, It should be obvious that the tool (PVA) is being used by scientists and ecosystems, and includes the native animals.

Question 2.  PVA has been used in Australia for many years.
Answer: NO.

Explanation: Part A of the reading passage indicates that-

"It (PVA) has been successfully used in the United States... ...and there is now an enormous potential for using population viability to assist wildlife management in Australia’s forests."

It should be clear that PVA is yet to be used in Australia but it has the potential to become handy to assist wildlife managements in Australia's forests. Potential means 'possible, likely, prospective, future, and probable' which clearly explains that it might be used in the future and has not been used and tested yet.  

Question 3: A species is said to be extinct when only one individual exists.
Answer: NO.

Explanation: Part A of the reading passage clearly mentions that "A species becomes extinct when the last individual dies." So finding the answer to this question should be very easy for you and this is quite straightforward. 

Question 4: Extinction is a naturally occurring phenomenon.
Answer: NOT GIVEN.

Explanation: According to the question instruction, we have to find evidence from Part A of this reading passage for question 4 as well.

Look at the last sentence in Part A which states -

"To make a prediction about extinction we need to understand the processes that can contribute to it and these fall into four broad categories which are discussed below."

It makes it clear that 'the reasons why extinction occurs' fall into four broad categories which we still don't know and would not want to know as they are not included in Part A of the reading passage. They might be a natural phenomenon or man-made.

Be aware: Do not apply your general knowledge or subject matter expertise while answering the IELTS reading passages. In reality, extinctions of different species might be a natural phenomenon. To answer this question you have to rely on the information given in this reading passage, not your previous knowledge or expertise.  

Tips: A group of questions (1-4 in this case) in IELTS reading usually appears chronologically; i.e. follow the order in the text of the passage. Since you found the answer to question 3 in the line "A species becomes extinct when the last individual dies", for the next question, we will start looking from the next line of this sentence, NOT from the beginning of the paragraph.

Questions 5- 8: Part B of the reading passage has four paragraphs namely a), b), c) and d). We need to find suitable processes that are listed in the table, i.e. i-vi. Do not write the process name in your answer sheet, rather write the roman numbers i - vi. Notice that there are six processes while you need to pick four out of these six to match with the 4 paragraphs given. 

Question 5: Paragraph A

Answer: vi  (The haphazard nature of reproduction) [In your answer sheet write only vi, we have included the answer in the () for the purpose of explaining it.]

Explanation: According to paragraph A) of Part B -

"Small populations will fluctuate enormously because of the random nature of birth and death and these chance fluctuations can cause species extinctions even if, on average, the population size should increase. Taking only this uncertainty of ability to reproduce into account, extinction is unlikely if the number of individuals in a population is above about 50 and the population is growing."

Main points/ keywords/ keyphrases to notice here - random nature of birth and death, the uncertainty of ability to reproduce into account. 

Thus "The haphazard nature of reproduction" is the most suitable process that the writer has described here. 

Question 6: Paragraph B

Answer: iii (An imbalance of the sexes) [In your answer sheet write only iii, we have included the answer in the () for the purpose of explaining it.]

Explanation: According to paragraph B) of Part B -

"This is particularly true if there is a very small number of one sex. For example, if there are only 20 individuals of a species and only one is a male, all future individuals in the species must be descended from that one male. For most animal species such individuals are less likely to survive and reproduce. Inbreeding increases the chance of extinction."

Thus "An imbalance of the sexes" is the process the writer has described in this paragraph.

Question 7: Paragraph C

Answer: i (Loss of ability to adapt) [In your answer sheet write only i, we have included the answer in the () for the purpose of explaining it.]

Explanation: According to paragraph C) of Part B -

"Without genetic variability, a species lacks the capacity to evolve and cannot adapt to changes in its environment or to new predators and new diseases. The loss of genetic diversity associated with reductions in population size will contribute to the likelihood of extinction."

Thus the "Loss of ability to adapt" is the process the writer has described in this paragraph.

Be aware that it is tempting to pick "Evolution" as the answer to this question if you do not understand the paragraph. It is talking about a process which lets a species go extinct and the lack/loss of adaptability is the right answer here, NOT the evaluation.

Question 8: Paragraph D

Answer: ii (Natural disasters) [In your answer sheet write only ii, we have included the answer in the () for the purpose of explaining it.]

Explanation: According to paragraph D) of Part B -

"Recent research has shown that other factors need to be considered. Australia’s environment fluctuates enormously from year to year. These fluctuations add yet another degree of uncertainty to the survival of many species. Catastrophes such as the fire, flood, drought or epidemic may reduce population sizes to a small fraction of their average level..."

Note that Environmental fluctuations, and catastrophes like floods, drought or epidemics are all 'natural disasters'.

Thus "Natural Disaster" is the process the writer has described in this paragraph.

Questions 9-11: Note that you have to answer questions 9 to 11 based on Part C of the paragraph. You need to fill the gaps with the word(s) that are TAKEN FROM THE PASSAGE and DO NOT use more than three words to fill in a single gap. Also, the sentence must make sense and should be grammatically accurate when you use your words to fill the gaps.

Question 9: While the population of a species may be on the increase, there is always a chance that small isolated groups .......... (9) ..........

Answer: (either one of the following) 

• become extinct
• will become extinct
• may become extinct
• could become extinct
• will not survive
• may not survive

Explanation: You have to pick "three" or "fewer than three" words to fill in this gap. Make sure you use word(s) that has/have appeared in the reading passage. In this case extinct and survive are both accurate as they both come from the reading passage. However, you have to use become, may become... will not survive or any of the right answers to make the sentence grammatically correct. 

You could be sure of this answer from the excerpt -

"A species that occurs in five isolated places each containing 20 individuals will not have the same probability of extinction as a species with a single population of 100 individuals in a single locality."

Question 10: Survival of a species depends on a balance between the size of a population and its .......... (10) .........

Answer: (either one of the following) 

• distribution
• locality

Explanation: You must not use more than three words to fill in this gap. Make sure you use the word(s) that has/have appeared in the reading passage. In this case extinct and survive are both accurate as they both come from the reading passage.

You could be sure of this answer from the line(s) -

"Besides these processes, we need to bear in mind the distribution of a population... ...Where logging occurs (that is, the cutting down of forests for timber) forest-dependent creatures in that area will be forced to leave. Ground-dwelling herbivores may return within a decade. However, arboreal marsupials (that is animals which live in trees) may not recover to pre-logging densities for over a century. As more forests are logged, animal population sizes will be reduced further. "

Question 11: The likelihood that animals which live in forests will become extinct is increased when ..........  (11) ...........

Answer: (either one of the following) 

• logging occurs
• logging takes place

Explanation: You must not use more than three words to fill in this gap. Make sure you use the word(s) that has/have appeared in the reading passage. In this case extinct and survive are both accurate as they both come from the reading passage.

You could be sure of this answer from the excerpt -

"Where logging occurs (that is, the cutting down of forests for timber) forest-dependent creatures in that area will be forced to leave. Ground-dwelling herbivores may return within a decade. However, arboreal marsupials (that is animals which live in trees) may not recover to pre-logging densities for over a century. As more forests are logged, animal population sizes will be reduced further. "

Caution: "logging occur/ logging take place" are grammatically inaccurate and hence if you write either of them, your answer would be treated as a wrong answer. The same rule applies to spelling mistakes. Even if your answer is correct, you won't get any marks for a spelling mistake. Thus 'loggin occurs' would NOT be treated as a correct answer as 'loggin' is not the correct spelling.

Question 12: An alternative heading for the passage could be:

Answer: B.

Explanation: The correct answer here would be "Influential factors in assessing survival probability" (i.e. B). The reading passage already has a heading, which is 'Population Viability Analysis'. This question now asks you to find an alternative and suitable heading for this same reading passage and the four options are given. By the time you have reached question 12, you already have a fairly good idea about the reading passage.

Option A) The protection of native flora and fauna - as an alternative heading is not at all suitable as the reading passage has not talked about how to protect the trees and animals. In the same way, option C) 'An economic rationale for the logging of forests' is totally off-topic.

Option D) includes 'Preventive measures for the extinction of a species' which is also off-topic as the reading passage is about the four main factors that could be used to assess the survival probability of a species.

Thus the most obvious choice is B) "Influential factors in assessing survival probability". 

This is the end of the "Answer Explanation" section for the reading passage "Population Viability Analysis".

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