Which mineral is the main component of bones and teeth along with calcium? MCQ with Answer and Explanation

Explanation:
Bacteria are unicellular prokaryotic organisms, characterized by the absence of a true nucleus and membrane-bound organelles. Fungi are eukaryotic organisms, possessing a true nucleus and membrane-bound organelles, and can be unicellular (yeasts) or multicellular (molds, mushrooms). Viruses are acellular, non-cellular entities; they consist of genetic material (DNA or RNA) enclosed in a protein coat (capsid) and lack any cellular structure or metabolic machinery. Thus, statements 1 and 2 are correct.

Explanation:
Mitosis is an equational division resulting in two genetically identical diploid daughter cells, not four. Meiosis is a reductional division involving two successive stages, meiosis I and meiosis II, producing four haploid cells. Crossing over, the exchange of genetic material, occurs exclusively during the pachytene stage of prophase I in meiosis, not in mitosis. Only statement 2 is correct.

Explanation:
Spectrophotometry quantifies the concentration of a substance by measuring the absorbance of light at specific wavelengths. Chromatography separates mixtures, electrophoresis separates charged molecules, centrifugation separates by density/size. Spectrophotometers are widely used in biochemical and clinical labs.