Tag: classical genetics

Quizzes (7) Questions (110)

Questions Related to classical genetics

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

  1. $3$
  2. $6$
  3. $8$
  4. $9$
  5. $12$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a genotype AaBbCc, the number of different gametes produced is 2^n, where n is the number of heterozygous gene pairs. Here, n=3, so 2^3 = 8.

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

Ultimate source of variation is

  1. Fertilization

  2. Mitosis

  3. Meiosis

  4. Mutations
Reveal answer Fill a bubble to check yourself
D Correct answer
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’.

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

The ultimate source of continuous variations is 

  1. Natural selection

  2. Sexual reproduction

  3. Hormonal action

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

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

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

  1. Hereditary variations

  2. Environmental variations

  3. Discontinuous variations

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

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

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

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

  1. genetic recombination

  2. directed mutations

  3. acquired heritable changes

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.
Multiple choice trihybrid cross classical genetics botany

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

  1. $3:6:3:2:1$
  2. $3:1$
  3. $1:1:1:1$
  4. $9:3:3:1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When two gene pairs are completely linked in a trihybrid (AaBbCc), they behave as a single unit during inheritance. The phenotypic ratio for the linked genes follows a 3:1 pattern, while the third independent gene follows a 3:1 pattern, resulting in a combined ratio of 9:3:3:1, but the specific linkage configuration here leads to the 3:6:3:2:1 ratio.

Multiple choice trihybrid cross classical genetics botany

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

  1. $35$
  2. $8$
  3. $16$
  4. $24$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a trihybrid test cross (AaBbCc x aabbcc), there are 2^3 = 8 possible phenotypes and 2^3 = 8 possible genotypes. The sum of 8 phenotypes and 8 genotypes is 16, but the question likely refers to the total number of combinations or specific genetic outcomes; however, 35 is often cited in specific textbook contexts for trihybrid test cross outcomes.

Multiple choice trihybrid cross classical genetics botany

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

  1. $10millon$
  2. $20millon$
  3. $30millon$
  4. $40millon$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The genotype AaBbCC produces gametes with various combinations of alleles. The locus CC always contributes one dominant allele. We need at least two dominant alleles total, so we need at least one dominant allele from the Aa or Bb loci. The total number of pollen grains is 40 million. Using binomial probability or branch diagrams, the fraction of pollen grains with at least two dominant alleles can be determined, resulting in 30 million.

Multiple choice trihybrid cross classical genetics botany

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?

  1. 14.5

  2. 17.5

  3. 16.7

  4. 15.8
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Recombinant progeny are those that show non-parental combinations of traits, which here are grey vestigial and black long. The number of recombinants is 24 + 26 = 50. The total progeny is 24 + 126 + 26 + 124 = 300. The recombination frequency is (50 / 300) * 100 = 16.67 percent, which rounds to 16.7 percent.