Passage - General Questions

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Passage Discussion

This Science passage addresses the new developments in lichen-forming fungi research, and then
discusses some of the implications of those developments.

Although the average student fi nds science-based passages intimidating, remember that they are in
no way different from any other type of passage. The subject matter and terminology is designed to
be daunting, so remember to keep focused on the structure of the passage, and do not get bogged
down in the details; you can always return to the passage later to confi rm the facts regarding a
diffi cult concept.

Paragraph 1 Overview

The author uses the fi rst paragraph to give defi nitions and introduce a discovery. The fi rst sentence
provides two defi nitions:

1. Lichen: a fungus living in symbiosis with an alga.
2. Symbiosis: a mutually benefi cial relationship.

The author then informs us that even though the evolutionary origins of lichen-forming fungi
have been a mystery, recent DNA evidence clears up the issue somewhat. Lichen-forming fungi
are closely related to common fungi, which accounts for the visual similarity of lichens to more
recognizable fungi.

Lines 6-8 state that new research has revealed the relationship of lichen-forming fungi to known
portions of the fungi family tree, and you should expect that the point of the passage is to explain
how that has occurred.

You should not focus too much on the examples that the passage gives. If you need to know about
Dutch elm disease or the like, you can look back at the fi rst paragraph.

Paragraph 2 Overview

The author explains why fungi are in general diffi cult to study, and why lichen-forming fungi are
particularly diffi cult to study:

1. In general, fungi are parasitic or symbiotic, which makes it diffi cult to separate them from
their host for study purposes.
2. Lichen-forming fungi are particularly diffi cult to differentiate from the host algae as they
are so intertwined.

Then, the author mentions that a new technique allows researchers to separate DNA more effectively
and then use the DNA testing results to understand the relationship of the lichen-forming fungi to
the fungi family tree. The researchers are establishing branches of the fungi family tree to which
the lichen-forming fungi belong, and further development of our understanding of these fungi is
expected.

You should take note of this general increase in understanding, and consider that a precise
understanding of why the testing works is probably not important.

Paragraph 3 Overview

The author proceeds to discuss an implication of the new research. The author believes that the
research may help overturn the assumption that interactions lead the fungi to become more symbiotic
over time. The author believes this because the new tree establishes that parasitic fungi can be found
both early and late in evolutionary history.

Characteristically, the author has offered a point that is somewhat questionable.
Even though the parasitic fungi exist both early and late in evolutionary history, that does not mean
that fungi do not, overall, evolve towards symbiosis. This inclusion of a highly questionable opinion
is common on recent LSAT reading passages, and even though you must be careful not to overreact
to it, you might expect to be questioned about this weakness.

Passage Summary

The point of the passage, as suggested in lines 6-8, is to show that new research has revealed the
close relation of lichen-forming fungi to known branches of the fungi family tree.

The structure of the passage is as follows:

Paragraph 1: Defi ne terms, introduce a mystery, and a resolving discovery.
Paragraph 2: Explain some diffi culties involved in studying fungi, and a particular resolving
method and results.
Paragraph 3: Provide an elaboration on the results.

The important elements in this passage consist of defi nitions, explanations of diffi culties, and results.
You should have noticed that the author’s elaborations in the last paragraph are questionable because
not enough evidence is provided to make such a broad statement, but you should not have spent too
much time critiquing the argument.