What is Double Fertilization? Explain Syngamy and Triple Fusion with their significance.

Here are the answers to Section A:

Q.1. योग्य पर्याय निवडून लिहा (MCQs):

1. Double fertilization is a unique characteristic feature of:

   • (d) Angiosperms
   • Explanation: Double fertilization, involving both syngamy and triple fusion, is a defining characteristic of flowering plants (angiosperms).

2. The phenotypic ratio of incomplete dominance in Mirabilis jalapa in F2 generation is:

   • (b) 1:2:1
   • Explanation: In incomplete dominance, the heterozygous genotype expresses an intermediate phenotype, leading to a 1:2:1 phenotypic ratio in the F2 generation (e.g., red:pink:white flowers).

3. Which of the following is an example of an X-linked recessive genetic disorder in humans?

   • (b) Haemophilia
   • Explanation: Haemophilia is a well-known X-linked recessive disorder, meaning the gene responsible is located on the X chromosome and the recessive allele causes the condition.

4. Outer protective exine layer of pollen grain is made up of:

   • (c) Sporopollenin
   • Explanation: Sporopollenin is one of the most resistant organic materials known, forming the tough outer layer (exine) of pollen grains, protecting them from degradation.

Q.2. एका वाक्यात उतरे लिहा (VSA):

1. Define Parthenocarpy.

   • Parthenocarpy is the development of fruit without fertilization, resulting in seedless fruits.

2. What is Co-dominance?

   • Co-dominance is a genetic phenomenon where both alleles in a heterozygous individual are fully and simultaneously expressed, resulting in a phenotype that shows both traits distinctly.

3. State the chromosomal condition (karyotype) in Turner's syndrome.

   • The chromosomal condition (karyotype) in Turner's syndrome is $\boxed{\text{45, XO}}$.