One of the following is not a descriptive study

Correct Answer: D

Rationale: Descriptive studies describe phenomena without manipulating variables. 'Comparative study,' is correct as not purely descriptive; it often infers differences or causality (e.g., Polit & Beck), unlike the others. 'Correlational study,' describes relationships. 'Cross sectional study,' captures a snapshot. 'Case study,' details a single case. Comparative studies' analytical bent distinguishes D as the exception.

Correct Answer: B

Rationale: Cell-mediated immunity involves T-lymphocytes targeting infected cells and coordinating responses, distinct from antibody-based defenses. 'Cell-mediated immunity,' is correct, as per immunology texts like Janeway's Immunobiology, highlighting T-cells' cytotoxic and helper roles. 'Humoral immunity,' relies on B-cells and antibodies. 'Innate immunity,' is non-specific, involving phagocytes, not T-cells primarily. 'Passive immunity,' transfers antibodies, not cellular action. T-cells' direct involvement in cell-mediated processes—like killing virus-infected cells—makes B the accurate answer, foundational to adaptive immunity's cellular arm.

Correct Answer: B

Rationale: Luteinizing hormone (LH) from the anterior pituitary stimulates testosterone production in testicular Leydig cells. 'Luteinising hormone,' is correct, per endocrinology texts like Guyton, driving male reproductive function. 'Follicle stimulating hormone,' targets spermatogenesis. 'Prolactin,' affects lactation, not testosterone. 'Oxytocin,' aids labor, not hormone secretion. LH's specific role in testosterone synthesis makes B the accurate answer, key to the hypothalamic-pituitary-gonadal axis.

Correct Answer: B

Rationale: Carbohydrates are the primary energy source, broken down into glucose for ATP production. 'Carbohydrates,' is correct, per biochemistry (e.g., Lehninger), yielding 4 kcal/g. 'Proteins,' are structural, used for energy secondarily. 'Vitamins,' and 'Minerals,' regulate processes, not energy suppliers. Carbohydrates' role as the body's main fuel, especially for brain and muscles, makes B the precise answer.

Correct Answer: B

Rationale: Amylase (salivary amylase or ptyalin) begins carbohydrate digestion in the mouth, breaking starches into maltose. 'Amylase,' is correct, per biochemistry (e.g., Lehninger). 'Lipase,' digests fats, mainly in the intestine. 'Protease,' targets proteins. 'Pepsin,' is gastric, for proteins. Amylase's oral action makes B the precise answer.