Question

Change in gene structure changes the trait it represents. The theory about the formation of new species with the help of such changes is :
(a)Theory of natural selection
(b)Mutation theory
(c)Theory of inheritance of acquired characters.
(d)Theory of biogenesis

Answer 1

Hint: This theory gives the idea that new species are formed from the sudden and unexpected emergence of alterations in their defining traits. Advanced at the beginning of the 20th century by Dutch botanist and geneticist Hugo de Vries.

Complete answer:
Mutations are the sudden changes that take place in the DNA sequence of an organism causing structural changes in genes.
These are the permanent changes that can be either induced or occur naturally which leads to the variation in the populations. Mutations are essential for speciation since variations are the raw material for evolution.

Additional Information: Salient Features of the Mutation Theory:
Based on the above observations, Hugo de Vries (1901) proposes a theory of evolution, called mutation theory. The theory conveys that evolution is a type of jerky process where new varieties and species are formed by mutations (discontinuous variations) that function as the raw material of evolution. The salient features of mutation theory are:
-Mutations or discontinuous variations are the main raw material of evolution.
-Mutations appear all of a sudden. They become operational immediately.
-Unlike Darwin's continuous variations or fluctuations, mutations don't revolve around the mean or normal character of the species.
-A similar kind of mutation can appear in several people of a species.
- Accumulation of variations produces new species. Sometimes a replacement species is produced from one mutation.
- Useful mutations are selected naturally. Lethal mutations are eliminated. However, useless and fewer harmful ones can continue the progeny.
-Mutations appear altogether conceivable directions.
- All mutations are inheritable.
- Evolution may be a jerky and discontinuous process.
So, the correct answer is 'Mutation theory.'

Note: -Significance of Hugo de Vries Mutation Theory:
-This theory gives direct attention to the mutations. But later on, it was thought that evolution cannot occur by mutations alone. Natural Selection and isolation of mutants were also essential for evolution.