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Question

Variations caused by mutation, as proposed by Hugo de Vries, are

A
small and directionless
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B
random and directional
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C
random and directionless
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D
small and directional
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Solution

The correct option is C random and directionless
Hugo de Vries, based on his work on Oenothera lamarckiana (evening primrose), proposed the mutation theory. In this theory, he explained that new species evolve by sudden and distinct heritable changes called mutations.

These mutations can occur any time and hence are random. These can be useful, harmful or have no effects at all on the organisms and hence are directionless.

As the mutations occur occasionally without prior precedent, they are termed as discontinuous heritable changes in the genetic material.

On the other hand, Darwin’s theory states that new variations appear in every generation (continuous) and such small variations accumulate over several generations by natural selection until the offspring become significantly different, thus evolving into a new species. Thus, Darwinian variations were considered small and directional.

Hugo de Vries believed that it is mutation which causes evolution and not the minor variations (heritable) that Darwin discussed in his theory.

Mutations are random and directionless while Darwinian variations are small and directional.

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