Question

Hugo de Vries contribution is:
A. Theory of Natural selection
B. Theory of mutations
C. Law of dominance
D. Law of segregation

Answer 1

Hint: Hugo de Vries proposed a theory which stated that evolution is caused by sudden discontinuous changes. These changes can go either ways, i.e. it can be beneficial as well as non-beneficial to the organism.

Complete answer:
Hugo de Vries was a Dutch botanist who gave the concept of mutation theory. He experimented on evening Primrose. He studied that new traits can be inherited that were not previously present in the ancestors. He stated that mutations lead to the formation of new species and are known as single step large mutation or saltation.
i. “Theory of natural selection” was given by Darwin. According to natural selection theory, organisms having traits that help them to survive are selected and will reproduce. It is also called the survival of fittest which supports the survival of species with favourable characteristics.
ii. The “Law of dominance” was given by Gregor Mendel. According to this law in the heterozygous state, the allele that expresses itself is known as the dominant allele and the allele which is masked is called a recessive allele. For example in heterozygous tall pea plant (Tt) T allele is dominant and t allele is recessive.
iii. The “Law of segregation” was also given by Gregor Mendel, which states that one of the two copies of the gene present in parents enters the gamete. This law was given by the monohybrid cross experiment.
Hence, the correct answer is option B.

Note: The salient features of mutation theory is that mutations appear all of a sudden. They become operational immediately. Unlike Darwin's continuous variations or fluctuations, mutations do not revolve around the mean or normal character of the species.