Question

Variation caused by mutation, as proposed by Hugo-de Vries is:
(A) Random and directional
(B) Random and directionless
(C) Small and directional
(D) Small and directionless

Answer 1

Hint: Hugo-de Vries put forward the theory of mutation that changes in DNA sequence and it causes variations which can be caused by inherited or environmental factors. These can be continuous or discontinuous.

Complete answer: According to the theory, living organisms can develop changes to their genes that greatly alter the organisms. These changes are passed down to the next generation and lead to the development of new species. Once a new species has evolved, it becomes fixed and stop changing.
Prior to Hugo-de Vries work, Charles Darwin had proposed his theory of natural selection as a slow, gradual change of species over time called ‘Gradualism’. They thought the process involved many small changes occurring and building up over many generations.
Hugo-de Vries disagreed with the slow and steady idea after seeing the ‘sudden’ mutations in the evening primrose plants. He believed that evolution could occur via discontinuous variations, or large changes happening in a few generations. This means that organisms can have drastic ‘jumps’ that immediately result in a new species coming into existence.
This theory also tells that living organisms can develop changes to their genes that greatly alter the organism. These changes are passed down to the next generation and lead to the development of new species.
Hence, the correct answer is option (B)-Random and directionless.

Note: Hugo-de Vries, a Dutch botanist, one of the independent rediscoveries of Mendelism, put forward his views regarding the formation of new species in 1901. He also met some of the objections found in Darwin’s theory.