Which vitamin is essential for the synthesis of prothrombin and blood clotting? MCQ with Answer and Explanation

Explanation:
Robert Hooke, in 1665, observed dead cork tissue under a microscope and coined the term 'cell' for the box-like structures he saw. Antonie van Leeuwenhoek, using his superior single-lens microscopes in the 1670s, was the first to observe and describe living microorganisms, including bacteria and protozoa. Charles Darwin proposed the theory of evolution by natural selection; the cell theory was proposed by Matthias Schleiden and Theodor Schwann. Thus, statements 1 and 2 are correct.

Explanation:
Colostrum, the first milk produced by the mother, is rich in IgA antibodies, providing natural passive immunity to the newborn. Allergies (hypersensitivities) occur when the immune system overreacts to harmless environmental antigens (allergens). Autoimmune diseases arise when the immune system loses tolerance and mistakenly attacks the body's own healthy cells and tissues. All statements are correct.

Explanation:
Ribosomes are dense, spherical, non-membranous structures composed of RNA and proteins. They are the cellular factories for protein synthesis. Prokaryotic ribosomes are 70S (50S + 30S subunits), while eukaryotic cytoplasmic ribosomes are 80S (60S + 40S subunits). Therefore, statements 1 and 3 are correct, but statement 2 is false.