Double fertilization is a unique characteristic feature of:

Here are the answers for Section B:

SECTION B (Short Answer - I : Any 4)

1. Distinguish between Self-pollination and Cross-pollination (any two points).

   • Self-pollination: Transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant. It does not introduce genetic variation.
   • Cross-pollination: Transfer of pollen grains from the anther of one flower to the stigma of another flower on a different plant of the same species. It introduces genetic variation.

2. State Mendel's Law of Segregation (Law of Purity of Gametes).

   • Mendel's Law of Segregation states that during the formation of gametes, the two alleles for a heritable character separate (segregate) from each other such that each gamete receives only one allele. These alleles then unite randomly during fertilization.

3. Explain the genetic mechanism of Sex Determination in Birds (ZW-ZZ method).

   • In birds, sex determination follows the ZW-ZZ system. Females are the heterogametic sex, possessing ZW chromosomes, while males are the homogametic sex, possessing ZZ chromosomes. The presence of the W chromosome determines femaleness, and its absence (ZZ) determines maleness.

4. Write any two outbreeding devices developed by flowering plants to prevent self-pollination.

   • Dichogamy: The anthers and stigma mature at different times in the same flower, preventing self-pollination. This can be protandry (anthers mature first) or protogyny (stigma matures first).
   • Herkogamy: There is a physical barrier between the anthers and stigma within the same flower, such as different positions or the presence of a hood, which prevents pollen from reaching the stigma of the same flower.

2 हो गए। आज 3 बाकी — अगला भेजो।