PrepTest 154, Section 4, Question 12
A lichen is made up of a photosynthetic(57 more words not shown)
Which one of the following(8 more words not shown)
- ALichens would not(14 more words not shown)
- BThe return of(12 more words not shown)
- CThe absence of(14 more words not shown)
- DThe photosynthetic organism(15 more words not shown)
- ESerious air pollution(8 more words not shown)
Reading the argument
What happens when a lichen absorbs something harmful and can't get rid of it?
A lichen has two partners growing together: a photosynthetic organism and a fungus. It absorbs material from the air, rainwater, and the surface beneath it, but cannot excrete the elements it takes in. That makes the next fact easy to connect: some varieties are very vulnerable to toxic compounds, including compounds in polluted air. Those compounds can damage both partners.
What we’re looking for
We don't have to turn that into a claim that every lichen exposed to any pollution will die. The supported point is simpler: air pollution can cause problems for lichens. For this inference question, keep the answer within the limits of the facts rather than trying to explain every place where lichens do or don't grow.
Working the answers
- A
Being able to excrete a substance wouldn't necessarily prevent it from causing damage first. Imagine a harmful material damaging an organism before the organism gets rid of it. That possibility shows the extra claim A makes. The passage says lichens cannot excrete absorbed elements; it doesn't establish that excretion would make them invulnerable.
- B
Lichens could return for a reason other than cleaner air. Perhaps more of the minerals they need become available while the air remains the same. That could make the location more suitable without establishing that its pollution has decreased. And only some varieties are described as very vulnerable. We can't treat the return of lichens as a reliable report on air quality without knowing more about why they returned.
- C
Their absence could also have another explanation. What if conditions were too cold for the lichens that might otherwise grow there? That's a possibility to illustrate the gap, not a new fact about their temperature limits. Knowing that pollution can damage lichens doesn't establish that pollution probably explains every place lacking them.
- D
Growing together doesn't tell us whether the two partners can thrive separately. Maybe each relies on something the other supplies. The passage describes the combined organism and damage to its partners; it gives no evidence that either partner can flourish independently.
- ECorrect
The passage tells us that some lichens are vulnerable to toxic compounds found in polluted air and that those compounds can damage both partners. So serious air pollution can cause problems for lichens. The modest word can matters: E doesn't claim that all pollution harms every variety or that pollution is the only reason lichens struggle.
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