Horizontal gene transfer occurs when an organism of one species acquires genetic material from an organism of another species through nonreproductive means. The genetic material can then be transferred "vertically" in the second species--that is, through reproductive inheritance. Scientist Atma lvancevic and her team have hypothesized infection by invertebrate parasites as a mechanism of horizontal gene transfer between vertebrate species: while feeding, a parasite could acquire a gene from one host, then relocate to a host from a different vertebrate species and transfer the gene to it in turn.

Which choice best describes the function of the underlined portion in the text as a whole?

Question

Accepted Answer

It describes a means by which horizontal gene transfer might occur among vertebrates.

Answer

It explains why parasites are less susceptible to horizontal gene transfer than their hosts are.

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It clarifies why some genes are more likely to be transferred horizontally than others are.

Answer

It contrasts how horizontal gene transfer occurs among vertebrates with how it occurs among invertebrates.