Question

What will be the ploidy of (i) embryo, (ii) perisperm and (iii) endosperm of seeds produced by a cross between a 4n female plant and a 2n male plant?

• A. (i)-3n, (ii)-4n & (iii)-5n
• B. (i)-3n, (ii)-3n & (iii)-5n
• C. (i)-4n, (ii)-3n & (iii)-4n
• D. (i)-2n, (ii)-2n & (iii)-3n

Answer 1

The correct option is A

(i)-3n, (ii)-4n & (iii)-5n

A ‘4n’ female plant on undergoing meiosis forms a ‘2n’ megaspore which develops into an embryo sac with all the cells having a ploidy of ‘2n’. Similarly, a ‘2n’ male plant will form male gametes with the ploidy of ‘n’. Hence, embryo produced is 3n (fusion of ‘2n’ egg and ‘n’ sperm) and endosperm is 5n (PEN formed from the fusion of two ‘2n’ polar nuclei i.e., ‘4n’ and on fusion with ‘n’ sperm forms ‘5n’ endosperm). Perisperm is nothing but the nucellus of female parent which is ‘4n’.