Question

According to theory put forth to explain the mechanism of organic evolution, when the structure of a gene undergoes a change, the trait it represents also changes. This results in a heritable variation in population, and may lead to the formation of new species. The above theory is known as
a. Theory of origin of species by natural selection
b. Mutation theory
c. Theory of inheritance of acquired characters
d. Theory of biogenesis

Answer 1

Hint: The changes that occur in an organism which cause genetic makeup of the species in a population as a result of responding to environmental changes is called organic evolution.

Complete answer:
Organic evolution is a selective force that acts for evolution in a species to take place. It emphasizes the descent and genetic differences that can be inherited by the offspring of the next generation. Genetic drift, mutation, migration and natural selection work as mechanisms of the change in organic evolution. It also describes the significance of genetic variation and impact of various species on each other’s evolution. It helps to figure out consequences of a reduction in genetic variation and nature of genetic drift. It also describes the role of differential reproduction, variation and heredity in evolution by natural selection.

Mutation is a force that drives evolution in a species. It makes a random change in the genetic composition of an organism causing an impact on the gene pool of a population. This change in the structure of DNA in one or more chromosomes results in producing a new allele which causes genetic variation. This change in allele causes change in traits represented by a gene as structure is gene changes. Elimination of less fit and allowing survival of fittest is decisive in mutation and occurs through natural selection.

Hence, the correct answer is option (B).

Note: There are other theories that are associated with organic evolution which are natural selection, Gene flow, genetic drift and development of species. Hugo de Vries stated this theory of Mutation.