Cholesterol is needed for formation of all except?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2021

Explanation

Vitamin A is the correct answer because it is not synthesized from cholesterol.
It is a fat-soluble vitamin that belongs to the terpene family of compounds.
The body obtains Vitamin A from dietary sources, such as beta-carotene found in vegetables or retinyl esters from animal-based foods.

Option B: This is incorrect because Vitamin D is directly synthesized from a cholesterol derivative.
Option C: This is incorrect because cholesterol is a fundamental structural part of animal cell membranes.
Option D: This is incorrect because cholesterol is the essential precursor for the synthesis of all steroid hormones.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biochemical derivatives of cholesterol as background academic context rather than a clinical decision trigger.
Understanding cholesterol's role is vital for managing hypercholesterolemia, a major risk factor for atherosclerosis and cardiovascular disease.
Statin medications work by inhibiting HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis, thereby lowering blood cholesterol levels.
What if? If a patient has a severe liver disease, their ability to synthesize cholesterol and its derivatives like bile acids would be impaired. This would lead to problems with fat digestion and absorption, as well as potential hormonal imbalances.

How to Approach the Question

This is a negative-framing question that uses the keyword 'EXCEPT', asking you to identify the outlier.
First, identify the core concept of the question, which is the biochemical products derived from cholesterol.
Systematically evaluate each option to determine its relationship with cholesterol.
Recall or deduce that Vitamin D, cell membranes, and steroid hormones are all directly linked to cholesterol as either a precursor or a structural component.
Identify Vitamin A as the substance not synthesized from cholesterol; it is obtained from the diet (e.g., from carrots).
Therefore, the correct answer is the option that is the exception to the rule.

Concept Tested & Keywords

QD7gRdB8yd074sDVKIQc9E

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 238-240

E6 Gynecology Williams p. 353-421

E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 83-85

Practise the full RUHS, Jaipur, M.Sc Nursing Entrance Exam-2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.