Tag: classical genetics

Questions Related to classical genetics

Laboratory mice are to be classified based on genes A, B, and C, none of  these are lethal genes. How many would be genetically different gametes if they are formed by genotype AaBbCc?

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

  1. $3$

  2. $6$

  3. $8$

  4. $9$

  5. $12$

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Correct Option: C

Ultimate source of variation is

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

  1. Fertilization

  2. Mitosis

  3. Meiosis

  4. Mutations

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Correct Option: D
Explanation:

Variation is a change or slight difference in condition, amount, or level, typically within certain limits appear in the progeny compared with parents. Variations appear in sexually reproducing organisms during meiosis and fertilization and also by mutations. So, the correct option is ‘Mutation’.

The ultimate source of continuous variations is 

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

  1. Natural selection

  2. Sexual reproduction

  3. Hormonal action

  4. Mutations

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Correct Option: B
Explanation:

Sexual reproduction involves gamete formation and fertilisation. During fertilisation, 1 gamete from each parent combines to form a zygote. Because of recombination and independent assortment in meiosis, each gamete contains a different set of DNA. This produces a unique combination of genes in the resulting zygote and ultimately within the organism.

As reproduction takes place continuously throughout the generation as well as these variations are inheritable, it is the ultimate source of continuous variations.
So, the correct option is 'Sexual reproduction.'

Which variations are temporary and are not connected with last or next generation?

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

  1. Hereditary variations

  2. Environmental variations

  3. Discontinuous variations

  4. Continuous variations

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Correct Option: B
Explanation:

In the living organisms, variation due to environment, not transmitted from generation to generation. so these are temporary, where as variations due to mutations are transmitted from generation to generation, so they are permanent. 

So, the correct option is 'Environmental variations'.

In introgressive hybridization, one species is completely replaced by another in nature.

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

  1. True

  2. False

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Correct Option: A
Explanation:
he movement of a gene (gene flow) from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species is called Introgressive hybridization.
So the given statement is true.

The most likely reason for the development of resistance against pesticides in insects damaging crops is:

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

  1. genetic recombination

  2. directed mutations

  3. acquired heritable changes

  4. none of these

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Correct Option: C
Explanation:
Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. Cases of resistance have been reported in all classes of pests (i.e. crop diseases, weeds, rodents, etc.), with 'crises' in insect control occurring early-on after the introduction of pesticide use in the 20th century. The Insecticide Resistance Action Committee (IRAC) definition of insecticide resistance is 'a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species'. Although the evolution of pesticide resistance is usually discussed as a result of pesticide use, it is important to keep in mind that pest populations can also adapt to non-chemical methods of control.
So the correct option is 'acquired heritable changes'.

What phenotypic ratio is obtained by selfing of a trihybrid in which two gene pair are completely linked?

trihybrid cross classical genetics botany

  1. $3:6:3:2:1$

  2. $3:1$

  3. $1:1:1:1$

  4. $9:3:3:1$

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Correct Option: A

What would be the sum of phenotypes and genotypes obtained from a trihybrid test cross?

trihybrid cross classical genetics botany

  1. $35$

  2. $8$

  3. $16$

  4. $24$

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Correct Option: A

A plant with genotype  AaBbCC produce $40millon$ pollen grains. Then calculate how many pollen grains will be with at least two dominant alleles?

trihybrid cross classical genetics botany

  1. $10millon$

  2. $20millon$

  3. $30millon$

  4. $40millon$

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Correct Option: A

In a cross in Drosophila, the heterozygous animal with grey body $(b+)$ and long wing $(vg+)$ with black body and vestigial wings, the progeny has the animals in the following ratio -grey vestigial 24 : grey long 126 : blck long 26 : black vestigial 124. What is the frequency of recombinants in the population?

trihybrid cross classical genetics botany

  1. 14.5

  2. 17.5

  3. 16.7

  4. 15.8

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Correct Option: A