Question

All cells of sex organs can form gametes in

• A. Algae
• B. Bryophyta
• C. Pteridophyta
• D. Gymnosperm

Answer 1

The correct option is A Algae

In sexual reproduction, there is an opportunity for exchange of genetic material and formation of new combinations. Sexual reproduction is not observed in cyanophyceae. It is not yet confirmed in Euglenophyceae. In all the other classes of algae, it is present. This is effected by three basic methods:

1. Isogamy

2. Anisogamy and

3. Oogamy.

In isogamy fusion occurs between two morphologically identical gametes.

Anisogamy involves the pairing of two dissimilar gametes, i.e., one gamete is smaller than the other. In certain cases the morphologically identical gametes behave differently, thus exhibit the physiological anisogamy. In some algae the gametes may be highly dimorphic. The larger, non motile gamete is called an egg or ovum and the smaller, motile one is called the sperm or spermatozoid.

A spermatozoid unites with an egg and this type of sexual reproduction is known as oogamy. After the fusion of the gametes a zygote is formed. The germination of zygote may vary in different algae but usually the contents divide to form zoospores. These zoospores germinate into the parent plant. In rare cases the zygote germinates directly into an adult plant. In Charophyceae, the germination of the zygote is indirect and produces a protonema from which the adult plant develops.

Therefore, the correct answer is option A.