Identify the correct statement about the human respiratory system: MCQ with Answer and Explanation

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:
Darwin's finches on the Galapagos Islands evolved diverse beak shapes from a common ancestor to adapt to different food sources, a classic example of adaptive radiation. Industrial melanism in the peppered moth demonstrates natural selection, where darker moths survived better in soot-covered environments. Homologous organs indicate divergent evolution from a common ancestor, whereas analogous organs indicate convergent evolution. Thus, statements 1 and 2 are correct.

Explanation:
All are correct: proteins are polymers of amino acids joined by peptide bonds; hemoglobin is a protein that transports oxygen in blood.