The human disease caused by the deficiency of vitamin B₃ (niacin) is: MCQ with Answer and Explanation

Explanation:
The anther is the male reproductive part of the flower where microspores develop into pollen grains. After fertilization, the ovary wall matures and develops into the fruit, enclosing the seeds. Self-pollination involves the transfer of pollen to the stigma of the same flower or plant, resulting in offspring genetically identical to the parent, thus decreasing, not increasing, genetic diversity. Thus, statements 1 and 2 are correct.

Explanation:
Meiosis involves two divisions reducing the chromosome number from diploid (2n) to haploid (n), producing gametes (sperm and egg). Mitosis maintains the chromosome number and produces identical somatic cells. Amitosis is direct nuclear division, budding is asexual reproduction. Meiosis ensures genetic diversity.

Explanation:
The Miller-Urey experiment (1953) simulated the conditions of the primitive Earth's atmosphere (methane, ammonia, hydrogen, and water vapor) in a closed system and applied electrical sparks to simulate lightning. After a week, they found that several organic compounds, including amino acids (the building blocks of proteins), had been synthesized, supporting the theory of chemical evolution.