This is an explanation for passage 3 of LSAT preptest 34, the June 2001 LSAT. This passage is about Lamarck’s theory of acquired characteristics and how modern evidence offers some support.
This section has paragraph summaries and an analysis of the passage, links to the explanations for the questions are below.
- Scientists thought Lamarck was wrong because they couldn’t find genetic evidence for his theory. Lamarck’s thought disuse or use of an organ would be passed on to an animal’s children.
- If you remove a cell wall from a bacteria, it will pass that on to its children without any genetic changes.
- Other examples: heating fly eggs will overcome poor genes. And bacteria can spread genes horizontally (meaning from one to another, not from parents to child).
- Some organisms can inherit genes horizontally, even between species. This may show Lamarck was right and that acquired characteristics can be inherited.
The scientific language in this passage might throw you off. It’s crucial to reread anything you’re not clear on. It takes more time, but it allows you to approach the questions with confidence.
The main theme of the passage is that organisms can acquire some characteristic without having inherited them genetically from their parents.
You don’t need to know all of the examples. You can refer back to the passage if needed. But you should understand vertical transmission (a parent giving genes to a child at birth) and horizontal transmission (one organism passing on a trait to another, not at birth).
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