Consider statements about vitamins: 1. Vitamin A deficiency causes night blindness. 2. Vitamin B1 deficiency causes beriberi. 3. Vitamin C deficiency causes rickets. Which are correct? MCQ with Answer and Explanation

Explanation:
O negative lacks A, B, and Rh antigens, so it can be given to anyone (RBCs). AB is universal recipient. Rh-negative lacks Rh antigen. Plasma is 90% water.

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:
Electron microscopes use beams of electrons to achieve much higher resolution than light microscopes, enabling visualization of organelles and macromolecular complexes. Types include TEM (internal) and SEM (surface). Light microscopes use visible light, spectrophotometry measures absorbance, chromatography separates.