Which of the following is absent in a prokaryotic cell? MCQ with Answer and Explanation

Explanation:
Vitamins are classified by their solubility. Vitamins A, D, E, and K are fat-soluble, meaning they are absorbed with dietary fats and can be stored in the body's liver and fatty tissues. Vitamins B-complex and C are water-soluble, meaning they dissolve in water and are generally not stored in significant amounts. Vitamin D (cholecalciferol) is unique because it can be synthesized endogenously in the skin when exposed to ultraviolet B (UVB) radiation from sunlight. All statements are correct.

Explanation:
Innate immunity is the non-specific, inborn defense mechanism present from birth, providing immediate but general protection against pathogens. Acquired (adaptive) immunity is highly specific, targeting particular antigens and developing memory. The secondary immune response, occurring upon re-exposure to the same antigen, is much faster, stronger, and more prolonged than the primary response due to the presence of memory cells. Thus, statements 1 and 2 are correct.

Explanation:
Robert Hooke observed cork tissue in 1665 and coined the term 'cell' to describe the box-like structures. Matthias Schleiden, a botanist, concluded in 1838 that all plants are composed of cells, forming a core tenet of the cell theory. The cell nucleus was discovered by Robert Brown in 1831, not Antonie van Leeuwenhoek, who is famous for discovering living microorganisms. Thus, statements 1 and 3 are correct.