Tag: introduction to genetics

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

Which is the source of variations?

  1. Mutation

  2. Recombination

  3. Deletion

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mutations, recombinations and deletions all are the sources of genetic variation. A Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene. Recombination involves the exchange of genetic material either between multiple chromosomes or between different regions of the same chromosome. Deletion is a mutation in which a part of a chromosome or a DNA sequence is missing. 

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

Which is a source of variation and genetic diversity that is shared between prokaryotes and eukaryotes?

  1. Random fertilization involving a unique sperm and a unique egg

  2. Independent assortment of each chromosome pair during metaphase I of meiosis

  3. Crossing-over during prophase I of meiosis

  4. Random mutation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The genetic material in prokaryotes is not confined into a nucleus and they do not have a nuclear membrane and the genetic material is present in the form of chromatin and cytoplasm and there is no chance of crossing over during meiosis and no fertilization but random mutations do arise in them and it results change in the genetic material.

So, the correct option is 'Random mutation'

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

The major/ ultimate source of variations are

  1. Polyploidy

  2. Mutations

  3. Chromosome aberrations

  4. Segregation
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.
Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

Discontinuous variations are :

  1. Essential features

  2. Acquired character

  3. Non-essential changes

  4. Mutations
Reveal answer Fill a bubble to check yourself
D Correct answer
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'
Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

Height in humans is

  1. Somatogenic variation

  2. Discontinuous variation

  3. Continuous variation

  4. Both B and C
Reveal answer Fill a bubble to check yourself
C Correct answer
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’.

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

Primary source of allelic variation is

  1. Independent assortment

  2. Recombination

  3. Mutation

  4. Polyploidy
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

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

Mutations are responsible for.

  1. Extinction of organisms

  2. Variations in population

  3. Increase in population

  4. Maintaining genetic continuity
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.
Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

Recombinations and variations in eucaryotic organisms are due to

  1. Mitosis and meiosis

  2. Fertilization and mitosis

  3. Meiosis and fertilisation

  4. Meiosis and amitosis
Reveal answer Fill a bubble to check yourself
C Correct answer
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’.