In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosome is/are

I. large chromosome

II. small chromosome

III. Y-chromosome

IV. X-chromosome
A. (i) and (ii)

B. (iii) only

C. (iii) and (iv)

D. (ii) and (iv)

Which statement is true for a dominant allele?

A recessive homozygote is crossed with a heterozygote of the same gene. What will be the phenotype of the F 1 -generation?

What determines the sex of a child?

The genotype of the height of an organism is written as Tt. What conclusion may be drawn?

Which statement about the genotypes of organisms is correct?

In the second generation, the dwarf trait reappears during Mendel’s experiment in monohybrid cross. Why so?

The genotype of green-stemmed tomato plants is denoted as GG and that of purple-stemmed tomato plants as gg. When these two are crossed,

i. What colour of stem would you expect in their F₁ progeny?

ii. Give the percentage of purple-stemmed plants if F₁ plants are self-pollinated.

iii. In what ratio would you find the genotypes GG and Gg in the F₂ progeny?

How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?

In one of his experiments with pea plants, Mendel observed that when a pure tall pea plant is crossed with a pure dwarf pea plant, in the first generation, F1 only tall plants appear.

i. What happens to the traits of the dwarf plants in this case?

ii. When the F1 generation plants were self-fertilised, he observed that in the plants of the second generation, F2 both tall plants and dwarf plants were present. Why it happened? Explain briefly.