Test: Pre-Fertilisation Events (Old NCERT) - Grade 12 MCQ

• The pollen grains carry the male organ. Mostly the male organs are the motile gamete while the female organ is stationary.
• It is necessary for the male organs to be small and light for easy propagation by the environmental agents.

Meiocytes are cells in diploid organisms that undergo meiosis. Meiosis is the process of producing 4 haploid cells from a single cell that has been divided twice. The haploid cell then becomes diploid after its fusion with the other sex gamete.

All heterogametic species can produce 2 types of gametes, male and female, their sex chromosomes are unidentical. Homogametic species the sex chromosomes are identical.

• Cockroach is an example of a unisexual organism, which means it can produce only one type of gamete, either male or female.
• Leech, tapeworm and earthworm are bisexual organisms, organisms that can produce both gametes.

A plant having both reproductive organs in the same plant is known as monoecious plants. It may also be known as homothallic conditions.
Dioecious plants are those which have only one reproductive organ, also known as unisexual plants. Another word for dioecious plants is heterothallic.

Stamens are the male organs of a flower. Flowers maybe unisexual (either staminate or pistillate). In staminate plants only the male part, that is the stamen, is present and in the pistillate plants only the female part is present (ovaries). In bisexual plants, both are present.

Male gamete is called antherozoid or sperm. They are called so in heterogametes. The two gametes produced are morphologically distinct types. The female gamete is called egg or ovum.

Gametogenesis refers to the formation of the gametes. In sexual reproduction formation of gametes is very important since an offspring is formed only after the fusion of the gametes. Gamete transfer refers to bringing the 2 gametes together.

Fertilization is the most important event in sexual reproduction. It is the process of fusion of 2 haploid gametes of different sex, forming one single diploid zygote. Also known as syngamy.

Syngamy is the process of fusion of a haploid male(n) and a haploid female(n) gamete. On fusion, the zygote or the egg formed is diploid(2n). Often this process is also known as fertilization.