Question

If the number of chromosomes in root of maize is 20 then the number of chromosomes are 10 and 30 in _______ and ________ respectively.

• A. male gametes and endosperm
• B. nucellus and pollen grain
• C. endosperm and pollen grain
• D. embryo sac and central cell

Answer 1

The correct option is A male gametes and endosperm

Since it is given that root cells (diploid) have 20 chromosome, other cells like the meiocyte also called microspore mother cell (diploid cells that give rise to haploid gametes) of a maize plant also contains 20 chromosomes. We know, if a meiocyte have 20 chromosomes then the gamete cell is half of it, i.e., n=10, so the gamete will have 10 chromosomes. Endosperm is triploid in nature and have 3n, i.e., 30 chromosomes. Then the number of chromosomes in the endosperm (triploid tissue that nourishes embryo) and male gamete (haploid) of the maize grain are 30 and 10 respectively.

Nucellus (diploid) is the central part of plant ovule enclosing female gametophyte called embro sac (haploid).

Central cell is a part of embryo sac having 2 haploid polar nuclei.

Pollen grain is male gametophyte bearing structure. It is haploid.