Consider the following statements about the immune system: 1. Macrophages are phagocytic cells. 2. B cells produce antibodies. 3. T cells are part of innate immunity. Which of the above is/are correct? MCQ with Answer and Explanation

Explanation:
Meiosis I features crossing over (prophase I) and independent assortment of homologous chromosomes, creating genetic diversity in gametes. Mitosis produces identical cells, binary fission is asexual, fragmentation is a form of asexual reproduction.

Explanation:
The question describes sieve elements, which are the conducting cells of the phloem, not xylem. Sieve tube elements are living but lack a nucleus at maturity and have perforated end walls called sieve plates. Xylem vessels and tracheids are dead, hollow, and lack perforated end walls (vessels have perforation plates, but they are not called sieve plates). Xylem parenchyma is living.

Explanation:
Vitamin K supports bone protein osteocalcin; D deficiency causes rickets. Vitamin A is retinol; vitamin E is tocopherol. So 3 is incorrect.