The pollen tube usually enters the embryo sac
through one of the synergids
by directly penetrating the egg
between one synergid and central cell
by knocking off the antipodal cells.
A.
through one of the synergids
The pollen tube arrives in the micropyle of the integument of the ovule, and enters the embryo sac.
The synergids of the embryo sac literally put their energies together to burst the end of the pollen tube. Meanwhile, the generative cell has followed the pathway digested by the tube cell. Along the way it has divided to produce two sperm cells. The two sperm cells exit the pollen tube through the burst end.
One sperm cell unites with the egg. This process is called syngamy (union of gametes) or [gag] fertilization. I much prefer syngamy to fertilization (see below). The product of the union of egg and sperm is called a zygote, and it has two sets of master plans, one from each gamete. The zygote will divide and grow and differentiate to become a new embryonic plant with root, stem, and leaf. Ultimately it will become an adult plant.
Assertion : Vegetable oils are fats which are present in plant cells in soluble form.
Reason : Vegetable oils occur only in cells of embryo.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Pollen grains are able to withstand extremes of temperature and dessication because their exine is composed of
cutin
suberin
sporopollenin
callose
In which one of the following would you expect to find glyoxysomes?
Endosperm of wheat
Endosperm of castor
Palisade cells in leaf
Root hairs
Plants of which one of the following groups of genera arc pollinated by the same agency
Triticum, Cocos, Mangifera
Ficus, Kigelia, Casuarina
Salvia, Morus, Euphorbia
Bombax, Butea, Bauhinia
When the pollen tube enters through the micropyle, it is termed as
chalazogamy
mesogamy
porogamy
none of these
Double fertilization involves
fertilization of the egg by two male gametes
fertilization of two eggs in the same embryo sac by two sperms brought by one pollen tube
fertilization of the egg and the central cell by two sperms brought by different pollen tubes
fertilization of the egg and the central cell by two sperms brought by the same pollen tube.
Assertion: Coconut tree is distributed in coastal areas over a large part of the world.
Reason: Coconut fruit can float and gel dispersed over thousands of kilometers before losing viability.
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
If Assertion is true but Reason is false
If both Assertion and Reason are false.
Assertion: Insects visit flowers to gather honey.
Reason: Attraction of flowers prevents the insects from damaging other parts of the plant.
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
If Assertion is true but Reason is false
If both Assertion and Reason are false.
