Human body, blood groups, genetics and common diseases MCQ - Practice Questions with Answers

The basic genetics terms carefully are distinct. A gene is a functional stretch of DNA, while a genome is the total hereditary material of an organism. Mutation means a change in genetic material. Humans normally have 23 chromosome pairs, of which 22 pairs are autosomes and one pair is sex chromosomes, so an autosome is a non-sex chromosome pair in this school-level framing. The matching that keeps these definitions separate is gene to functional DNA stretch, genome to total hereditary material, mutation to genetic change, and autosome to non-sex chromosome pair.

Homeostasis is the body’s regulation of a stable internal environment even when outside conditions change. Body temperature and blood glucose are given as examples of such control. Therefore, keeping blood glucose within a stable range is not just a random body function; it is a direct case of homeostasis. The reason states the general rule, and the assertion gives one example of that rule. This makes both statements true, with the reason correctly explaining the assertion.

The genetics notes make a precise vocabulary distinction: a gene is a functional stretch of DNA, and a genome is the total hereditary material of an organism. They also warn against a common examination error: a dominant trait is not automatically common or beneficial. Dominance only means that an allele can show its effect in a heterozygous condition. Therefore, the gene-genome statement is correct, but the statement about dominant alleles being always common and beneficial is not.

CET questions often confuse breathing with cellular respiration. Breathing is the mechanical movement of air in and out of the lungs. Cellular respiration is the process by which energy is released inside cells. Kidney filtration, haemoglobin transport and general gas exchange are related body functions, but they do not define this specific contrast. Therefore the correct distinction is that breathing moves air, while cellular respiration releases energy in cells.

The human ABO blood group is controlled by three alleles: IA, IB and i. A genotype is formed by taking two alleles at a time. The possible combinations are IAIA, IAi, IBIB, IBi, IAIB and ii, giving six genotypes in total. Four refers to the phenotypes A, B, AB and O, not genotypes. Three counts only the alleles. Eight is too high because the same two-allele combinations are not counted separately by order.