Tag: natural selection

Questions Related to natural selection

The major/ ultimate source of variations are

botany classical genetics variation and its type natural selection introduction to genetics

  1. Polyploidy

  2. Mutations

  3. Chromosome aberrations

  4. Segregation

Show answer
Correct Option: B
Explanation:
Ultimate source of variation is MUTATION and nothing else. Mutations are mistakes that occur in DNA sequence of genome:
  • Point mutation e.g. nonsense and missense mutations
  • Frame-shift mutation e.g. insertion or deletion mutations
Any change in genetic DNA will be translated into a defect in the corresponding protein. Thus mutation is responsible for appearance of a phenotypic variation. Such a variation may help the organisms carrying the new variation to survive better. If it produces more progeny the variation will appear in more members. Variations which provide adaptive advantage get selected by nature, thus help organisms to evolve.

So, the correct answer is 'Mutations'.

Cannibals feed on

botany classical genetics variation and its type natural selection introduction to genetics

  1. Carcases

  2. Blood

  3. Carnivores

  4. Members of own species

Show answer
Correct Option: D

Discontinuous variations are :

botany classical genetics variation and its type natural selection introduction to genetics

  1. Essential features

  2. Acquired character

  3. Non-essential changes

  4. Mutations

Show answer
Correct Option: D
Explanation:
Discontinuous variations are where individuals fall into a number of distinct classes or categories and are based on features that cannot be measured across a complete range. You either have the characteristic or you don't. 
Discontinuous variation is controlled by alleles of a single gene or a small number of genes. As variations caused by mutations affect DNA in such a way that either organism has a certain characteristic resulting from mutation or not, it is an example of discontinuous variations.
So, the correct answer is 'Mutations'

Height in humans is

botany classical genetics variation and its type natural selection introduction to genetics

  1. Somatogenic variation

  2. Discontinuous variation

  3. Continuous variation

  4. Both B and C

Show answer
Correct Option: C
Explanation:

A.Somatogenic variation – These are acquired variations and non inheritable in nature. Eg:phenotypic plasticiy.

B.Discontinuous variations – These are responsible for the formation of a new species and the organism, thus, formed is called mutant. Eg:Mutations.

C.Continuous variations – These are fluctuating variations and cannot give rise to new species. Eg:Human height.

So, the correct option is ‘Continuous variations’.

Primary source of allelic variation is

botany classical genetics variation and its type natural selection introduction to genetics

  1. Independent assortment

  2. Recombination

  3. Mutation

  4. Polyploidy

Show answer
Correct Option: B
Explanation:

Primary source of allelic variation is recombination. Recombination is the natural process of breaking and rejoining DNA strands to produce new combinations of genes and, thus, generate genetic variation. This is the phenomenon that occurs during meiosis I.


So, the correct answer is 'Recombination'.

Mutations are responsible for.

botany classical genetics variation and its type natural selection introduction to genetics

  1. Extinction of organisms

  2. Variations in population

  3. Increase in population

  4. Maintaining genetic continuity

Show answer
Correct Option: B
Explanation:
Mutations are changes in the DNA. A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations. Gene flow is any movement of genes from one population to another and is an important source of genetic variation.

So, the correct answer is 'Variations in population'.

Recombinations and variations in eucaryotic organisms are due to

botany classical genetics variation and its type natural selection introduction to genetics

  1. Mitosis and meiosis

  2. Fertilization and mitosis

  3. Meiosis and fertilisation

  4. Meiosis and amitosis

Show answer
Correct Option: C
Explanation:

The process of forming new allelic combination in offspring by exchanges between genetic materials of parents is called Recombination.

Variation is a change or slight difference in condition, amount, or level, typically within certain limits appear in the progeny compared with parents.

Recombination and variations appear in sexually reproducing organisms during meiosis and fertilization.

So, the correct option is ‘Meiosis and fertilization’.

Some individuals produce lesser amounts of insulin. It is a type of

botany classical genetics variation and its type natural selection introduction to genetics

  1. Physiological variation

  2. Behavioural variation

  3. Morphological variation

  4. All the above

Show answer
Correct Option: A
Explanation:
  • Physiological variation is related to the differences in the ways individuals of the same species react to conditions in their environment because of difference in their functioning of the body. Production of insulin is an example of physiological variation.
  • So, the correct option is 'Physiological variation'


Mutation, selection and genetic drift are three important forces which are responsible for evolutionary changes

botany classical genetics variation and its type natural selection introduction to genetics

  1. True

  2. False

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Correct Option: A
Explanation:

Evolution is dependent on the natural selection , genetic drift , gene flow , mutation are the main factors responsible for evolution .

Hence the given statement is true

Aspects such as sedentary habit, territoriality, etc., not aiding diversification are classified as 

botany classical genetics variation and its type natural selection introduction to genetics

  1. Reproductive isolation

  2. Mutational effects

  3. Biological barriers

  4. Genetic incompatibility

Show answer
Correct Option: C
Explanation:
Biological barriers are factors that prevent species migration, interbreeding, or free movement. What determines the barrier depends on the species and it's method of movement. For some species biological barriers are sedentary habits, physical like bodies of water, mountains, or deserts.
Mutation effects is the formation of altered protein from an altered or mutated genes.
When the species are not able to cross breed is called as genetic incompatibility
Thus, the correct answer is option C.