This set of Class 12 Biology Chapter 7 Multiple Choice Questions & Answers (MCQs) focuses on “Mechanism of Evolution”.
1. Hugo de Vries did an experiment on which plant to prove mutation theory?
a) Evening primrose
b) Morning primrose
c) Night primrose
d) Pea pant
Explanation: Hugo de Vries proved mutation theory by doing experiments on Oenothera lamarckian, also known as evening primrose. It was from this plant; he came up with the observations. It is a complex heterozygous plant with a chromosomal aberration.
2. Which of the following does not belong to Mutation theory?
a) It can appear in all direction
b) It is the raw material of evolution
c) It appears suddenly
d) It is a continuous process
Explanation: Mutation is a jerky and discontinuous process. Otherwise, it can appear in all direction and are inheritable. Also, it can appear suddenly and produce their effect immediately.
3. _______ is termed as single-step large mutation.
c) Anti mutation
d) Infinite mutation
Explanation: Single-step that causes large mutation is called saltation. It is called as such because the mutation occurs suddenly and abruptly that leads to evolution in large scale. Hugo de Vries used this term against Darwin’s theory of evolution.
4. Mutations are small and directional whereas Darwinism variations are random and directionless.
Explanation: It is a wrong statement. The statement should be in opposite manner i.e. mutations are random and directionless, whereas Darwinism variations are small and directional.
5. Which of the following point favor mutation theory?
a) Mutations are not very common
b) Mutations are mostly recessive
c) Mutation give rise to new varieties
d) Evening primrose is not a normal plant
Explanation: A number of mutations appear in nature and some mutations are also induced which have given rise to variations. This theory could explain both progressive and retrogressive evolution. The remaining options are against mutation theory.
6. Mutation theory couldn’t explain _______
a) development of mimicry
d) chromosomes of flowers
Explanation: One of the drawbacks of mutation theory was that it couldn’t explain the development of mimicry, the relationship between the position of nectars in flower and also length of proboscis in their insect pollinators. The problem was that these cannot be imagined to have developed all of a sudden.
7. Who proposed the Evolutionary species concept?
a) Hugo de Vries
b) Charles Robert Darwin
c) George Gaylord Simpson
d) Gregor Johann Mendel
Explanation: Evolutionary species concept was given by George Gaylord Simpson. According to this concept, a species is an ancestor sequence of the population that evolved separately from other species and has its own evolutionary role and tendencies. This concept also includes evolution.
8. Which is the most accepted concept of species?
a) Biological species concept
b) Evolutionary species concept
c) Polytypic species concept
d) Typological species concept
Explanation: Typological species concept is the most accepted concept of species. According to this concept, a fixed pattern of characters is visible in the species of every living organism. All the members of that species show maximum resemblance with this pattern.
9. The process of formation of one or more new species from an existing species is called ______
Explanation: The process of formation of one or more species from an existing species is called Speciation. It is of two types, mainly: Divergent speciation and Transformation speciation. Speciation was one of the main theories of Darwin.
10. The local population of a particular area is known by a term called ______
Explanation: Local population of a particular area is called demes. The members of two different demes of the same species can interbreed. Races are small groups of species which are geographically isolated and have some genetic difference, which is controlled by genes.
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