Question

A theory explaining the mechanism of evolution based on the change of gene structure was put forward by:
(a) De Vries
(b) Darwin
(c) Lamarck
(d) Wallace

Answer 1

Hint: A Dutch botanist who was among the first geneticists to give about the concept of the genes and was working parallel to Gregor's Mendel who was working on mutation. He was the one to rediscover the laws of genetics.

Complete answer:
Hugo de Vries explained the mechanism of evolution based on the gene structure which is also called mutation theory. This theory involves the changes that occur in the structure of the genes that are the result of the addition, deletion, inversion, or substitution of nucleotides.
- Hugo de Vries named genes as pangenes in his book Intracellular Pangenesis, after Darwin’s theory of Pangenesis.
- Although Mendel was working on the laws of inheritance in genetics, de Vries was unaware of it.
- He worked on the law of segregation, the law of dominance, and the law of assortment on his own in his experiments to find the 3:1 ratio in the second generation of the plants.
- He suggested that the same gene is sometimes responsible for the appearance of a particular character in two different species.
- He was well known for his work on mutation theory and found new forms of the Evening Primrose.
- He discovered many new varieties by taking several seeds from the plant.
- He then postulated that evolution occurs frequently on a large scale and this gives rise to the origin of the new species.
- These changes occur due to the mutation occurring in the sequence of the DNA resulting in the origin of new species.
So, the correct answer is ‘De Vries’.

Note: Charles Darwin is called the ‘Father of Genetics’. He is best known for his work in the field of evolution and for introducing the theory of evolution. John Baptiste Lamarck was a French biologist and naturalist who is well known for his contributions to biological evolution. He also worked on the classification of invertebrates which he published in 1801. Alfred Wallace was also known for his work on the theory of evolution independently. He is sometimes called the ‘Father of Biogeography’.