The Biological Oxygen Demand (BOD) measures: MCQ with Answer and Explanation

Explanation:
DNA (deoxyribonucleic acid) typically exists as a double-stranded helical molecule, with two complementary strands held together by hydrogen bonds between base pairs. RNA (ribonucleic acid) is generally single-stranded, allowing it to fold into complex three-dimensional shapes necessary for its various functions (mRNA, tRNA, rRNA). DNA contains the nitrogenous bases adenine, guanine, cytosine, and thymine; it does not contain uracil, which is found in RNA instead of thymine. Thus, statements 1 and 2 are correct.

Explanation:
Proteins are polymers of amino acids. The amino acids are linked together by peptide bonds, which are covalent bonds formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of the next, with the release of a water molecule (dehydration synthesis). Glycosidic bonds link sugars, and phosphodiester bonds link nucleotides.

Explanation:
The endocrine islets of Langerhans in the pancreas contain alpha cells that secrete glucagon and beta cells that secrete insulin, which regulate blood glucose. The liver stores and releases glucose, the spleen filters blood, the kidneys excrete waste. The pancreas also has exocrine functions secreting digestive enzymes.