LSAT 138 – Section 4 – Question 24

LSAT 138 - Section 4 - Question 24

December 2012

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Question QuickView	Type	Tags	Answer Choices	Curve	Question Difficulty	Psg/Game/S Difficulty	Explanation
PT138 S4 Q24	+LR +Exp	Most strongly supported +MSS Conditional Reasoning +CondR Rule-Application +RuleApp	A 4% 161 B 14% 159 C 70% 166 D 10% 160 E 2% 154	146 156 166	+Harder	146.393 +SubsectionMedium

Mammals cannot digest cellulose and therefore cannot directly obtain glucose from wood. Mushrooms can, however; and some mushrooms use cellulose to make highly branched polymers, the branches of which are a form of glucose called beta-glucans. Beta-glucan extracts from various types of mushrooms slow, reverse, or prevent the growth of cancerous tumors in mammals, and the antitumor activity of beta-glucans increases as the degree of branching increases. These extracts prevent tumor growth not by killing cancer cells directly but by increasing immune-cell activity.

Summary

Mammals cannot absorb glucose from wood because they cannot digest cellulose. However, mushrooms can digest cellulose and some mushrooms use it to make branches of polymers that form a type of glucose called beta-glucans. Beta-glucan extracts from some types of mushrooms prevent cancerous tumors from growing in mammals. This antitumor activity increases as the degree of branching increases. Beta-glucan extracts kill cancer cells by increasing immune-cell activity, not by killing cancer cells directly.

Strongly Supported Conclusions

The more branching that occurs in the production of beta-glucans, the stronger the effect of increasing immune-cell activity.

Mammals obtain no beneficial health effects from eating cellulose.

We don’t know if mammals receive no beneficial health effects from eating cellulose. We only know that mammals cannot digest cellulose.

If extracts from a type of mushroom slow, reverse, or prevent the growth of cancerous tumors in mammals, then the mushroom is capable of using cellulose to make beta-glucans.

We only know that the reverse of this relationship is true in some instances. It is possible that there is a type of mushroom that does not produce beta-glucans but also produces antitumor extracts.

The greater the degree of branching of beta-glucans, the greater the degree of immune-cell activity it triggers in mammals.

We know that the greater degree of branching, the greater degree of antitumor activity. Since antitumor activity is also strongly correlated with immune-cell activity, we can effectively say that the more branching, the more immune-cell activity.

Immune-cell activity in mammals does not prevent tumor growth by killing cancer cells.

We only know that beta-glucans do not kill cancer cells directly. It is possible that a mammal’s immune cells prevent tumors by killing cancer cells directly.

Any organism capable of obtaining glucose from wood can use cellulose to make beta-glucans.

We don’t know whether any organism could do this. We only know that mushrooms are one example of an organism capable of obtaining glucose from wood and then using cellulose to make beta-glucans.

LSAT 138 – Section 4 – Question 24

LSAT 138 - Section 4 - Question 24

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LSAT PrepTest 138 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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