Pollen grains are able to withstand extremes of temperature and dessication because their exine is composed of

(1) cutin

(2) suberin

(3) sporopollenin

(4) callose

The pollen tube usually enters the embryo sac

(1) through one of the synergids

(2) by directly penetrating the egg

(3) between one synergid and central cell

(4) by knocking off the antipodal cells

Double fertilization involves

(1) fertilization of the egg by two male gametes

(2) fertilization of two eggs in the same embryo sac by two sperms brought by one pollen tube

(3) fertilization of the egg and the central cell by two sperms brought by different pollen tubes

(4) fertilization of the egg and the central cell by two sperms brought by the same pollen tube.

What is the charasteristic of tapetum ?

(1) It does not store food.

(2) It is multi-nucleated.

(3) It is multi-layered structure.

(4) It nourishes the megaspore.

The pollen grains of rice and wheat lose their viability in ___ minutes of their release.

(1) 30

(2) 10

(3) 60

(4) 90

After double fertilizaton, a mature ovule has

(1) 1 diploid and 1 haploid cell

(2) 1 diploid and 1 triploid cell

(3) 2 haploid and 1 triploid cell

(4) 1 haploid and 1 triploid cell

How many haploid nuclei are present in a mature pollen grain?

(1) One

(2) Two

(3) Three

(4) Four

What is the correct sequence of the formation of female gametophyte in angiosperms?

(1) Nucellus, megapore tetrad, megaspore mother cell, megaspore, female gametophyte

(2) Megaspore tetrad, nucellus, megaspore mother cell, megaspore, female gametophyte

(3) Nucellus, megaspore mother cell, megaspore tetrad, megaspore, female gametophyte

(4) Megaspore mother cell, megaspore tetrad, megaspore, nucellus, female gametophyte

Primary endosperm nucleus (PEN) is formed by the fusion of

1. 2 polar nuclei + 1 synergid cell nucleus

2. 1 polar nucleus + 1 antipodal cell nucleus + 1 synergid cell nucleus

3. 2 polar nuclei + 1 male gamete nucleus

4. 2 antipodal cell nuclei + 1 male gamete nucleus

Identify the parts labelled A, B, C and D in the given figure and select the correct option.