Question 1

Assertion : Double fertilization is characteristic feature of angiosperms. Reason : Double fertilization involves two fusions.

Accepted Answer

Double fertilization is a characteristic feature of angiosperms. It involves two fusions in which one female gametes fuse with egg cell to form zygote and other male gamete fuses with the diploid secondary nucleus to produce triploid primary endosperm nucleus.Hence, both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

Question 2

Double fertilization is -

Accepted Answer

[D] In angiosperm double fertilization occurs that includes syngamy and triple fusion

Question 3

Which of the following is without exception in angiosperms

Accepted Answer

[C] Double fertilization is found only in angiosperms. In which secondary nucleus form to triploid cell and egg convert into diploid zygote. Triploid cell to form endosperm and diploid zygote to form embryo.

Question 4

Which of the following is not true for double fertilization

Accepted Answer

[C] Endosperm is triploid (3n)

Question 5

Which one is an example of triploid tissue

Accepted Answer

.[C] Because maize and lily are angiosperm plants, in which endosperm is formed by fusion of one diploid polar nucleus and haploid male gamete, thus this tissue is triploid.

Question 6

Fusion product of polar nuclei and male gamete is

Accepted Answer

[B] Primary endosperm nucleus is triploid structure which forms endosperm.

Question 7

During double fertilization in plants, one sperm fuses with the egg cell and the other sperm fuses with

Accepted Answer

During double fertilization in plants one sperm fuses with the egg cell and the other sperm fuses with two polar nucleus of the central cell to produce triploid primary endosperm cell (3n). Since the latter involves fusion of three haploid nucleus therefore it is called triple fusion.

Question 8

Which one of the following statement is incorrect?

Accepted Answer

In over 60 per cent of angiosperms, pollen grains are shed at cell 2-celled stage. In the remaining species the generative cell divides mitotically to give rise to the two male gametes before pollen grains are shed (3-celled stage.)

Question 9

Which one of the following events takes place after double fertilization?

Accepted Answer

Double fertilization forms a diploid zygote nucleus and a triploid primary endosperm nucleus (PEN). After that, the two products of double fertilization i.e., zygote and PEN, develop into embryo and endosperm respectively

Question 10

The total number of nuclei involved in double fertilization in angiosperms are

Accepted Answer

In the cytoplasm of the synergid pollen tube releases the two male gametes. After reaching ovary the pollen tube enters the ovule. One of these male gametes fuses with egg to form diploid zygote (2n) while the other uses with two polar nucleus of the central cell to produce triploid primary endosperm cell (PEC) (3n). So, in some angiosperms these two types of fusion occur in the same embryo sac. This phenomenon is called double fertilization.

Question 11

Double fertilization leading to initiation of endosperm in angiosperms require

Accepted Answer

The second male gamete entering the ovary fuses with two haploid polar nuclei to form a triploid primary endosperm nucleus which develops into endosperm. This fusion of two male gametes with two different structures (egg and secondary nucleus) in the same female gametophyte is called double fertilization.

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