Pollen grains are able to withstand extremes of temperature and dessication because their exine is composed of
cutin
suberin
sporopollenin
callose
C.
sporopollenin
Exine is outer layer of pollen grain which is acetolysis resistant layer. It is also resistant to physical and biological degradation. Because of this property of exine, pollen grains are found well preserved for long periods in fossil deposits.
Cutin is a waxy repellant substance in the cuticle of plants, consisting of higly polymerized esters of fatty acids.
Suberin is an inert impermeable waxy substance present in the cell walls of corky tissues.
Callose is a plant polysaccharide. It plays an important in plant development.
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.
In which one of the following would you expect to find glyoxysomes?
Endosperm of wheat
Endosperm of castor
Palisade cells in leaf
Root hairs
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.
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
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
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.
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.
