Question

Sometimes, diploid cells in the integument surrounding the embryo sac form another diploid embryo sac. The second embryo sac

Select one:

a. develops into a deformed embryo and seed.

b. forms a normal embryo and seed that is a clone of the parent.

c. forms an embryo and seed with a 3n, rather than a 2n, chromosome number.

d. forms a normal embryo and seed that are genetically different from the parent.

e. dies, because it did not originate from an egg cell and cannot form an embryo or seed.

Answer 1

Solution:

​​​​​​In Spiranthus australis, the embryo sac is developed from Integuments ( called Adventive Polyembrony).

The embryo that is formed from fertilization of male and female gametes can also be formed without fertilization and meiotic division. In this condition, seeds are formed but embroy formation doesn't include syngamy and meiosis. This is called Agamospermy. It is of 3 types,

In one method, the embroy is formed from the cells of Integuments of the ovule. This method is called Adventive Polyembrony. Integuments in this condition behaves like zygote. The embroy sac and embroy formed from Integuments is normal and is a clone of the parental sac as it is formed from cells of parental embroy sac.

Hence, Option B) forms a normal embryo and seed that is clone of the parent, is the correct answer.