Question

Chalazogamy occurs in
A. Cucurbita
B. Lily
C. Populous
D. Casuarina

Answer 1

Hint:
The phenomena of how and from where the pollen tube enters the ovule for the fertilization to take place, is different in different plants. It involves the chalaza tissue which means the basal part of the ovum, entry of the pollen tube denotes a different name to the fertilization fusion process.

Complete answer:
If the pollen tube enters from chalaza – basal part of ovum but not from the ordinary micropyle cell it is known to be chalazogamy.
In this pollen tube (anther) grows in the nucellus and destroys the embryo sac ( near micropyle) – the process of chalazogamy.
Chalaza is a form of tissue which is situated at the place where integuments and nucellus are joined.
Chalaza helps in the transport of nutrients and water to the egg cell through nucellus.
It usually occurs in monoecious plants.
It is more often observed in pistachio and walnut plants.
It occurs in some animals and usually in birds but not occurs in reptiles.
In animals, they are usually two bands of spiral present submerged in the yolk.

The correct answer is option (D) Casuarina.

Note: Entry of pollen tube into the ovule is one of the pre-fertilization events. In Cucurbita, pollen tubes enter through integuments and also in Populus pollen tube enters through integuments, this phenomena is known as misogamy whereas in lily plant pollen tube dissects the embryo sac of ovule through the micropyle, this phenomenon is known to be porogamy in plants.