A common test to find the genotype of a hybrid is by

  • crossing of one F2 progeny with male parent

  • crossing of one F2 progeny with female parent

  • studying the sexual behaviour of F1 progenies

  • studying the sexual behaviour of F1 progenies


D.

studying the sexual behaviour of F1 progenies

Test cross, crossing of F1 progeny to the recessive parent is used to find the genotype of the progeny.

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Two genes R and Y are located very close on the chromosomal linkage map of a maize plant. When RRYY and rryy genotypes are hybridised, the F2 segregation will show:

  • higher number of the recombinant types.

  • segregation in the expected 9 : 3 : 3 : 1 ratio

  • segregation in 3 : 1 ratio

  • segregation in 3 : 1 ratio


D.

segregation in 3 : 1 ratio

Law of independent assortment does not applicable when the gene of different character occupy on the same homologous chromosome i.e., linked gene.

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A human male produces sperms with the genotypes AB, Ab, aB, and ab pertaining to two diallelic characters in equal proportions. What is the corresponding genotype of this person?

  • AaBb

  • AaBB

  • AABb

  • AABb


A.

AaBb

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Haploids are more suitable for mutation studies than the diploids. This is because 

  • Haploids are reproductively more stable than diploids

  • mutagens penetrate in haploids more effectively than is diploids

  • haploids are more abundant in nature than diploids

  • haploids are more abundant in nature than diploids


D.

haploids are more abundant in nature than diploids

Haploid plants can be produced in large number by anther and ovary cultures. Haploids may be useful for isolation of mutants, since, even recessive mutant alleles will be expressed in the mutagen treated generation itself. Desirable mutants may be selected at the haploid level and their chromosome number may be doubled to obtain homozygous mutant lines in a single generation.

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Inheritance of skin colour in humans is an example of

  • chromosomal aberration

  • point mutation

  • polygenic inheritance

  • polygenic inheritance


C.

polygenic inheritance

Inheritance of skin colour in humans is the result of polygenic inheritance or multiple factor inheritance. The inheritance of human skin colour was studied by C.B. Davenport in 1913.

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