CDN Nutritional Science & Dietetics 2

Question 1

Which fatty acid is classified as essential because humans cannot synthesize it?

Accepted Answer

Linoleic acid (18:2n-6)

Answer

Linoleic acid is an essential omega-6 fatty acid that must be obtained from the diet because humans lack the delta-12 desaturase enzyme needed to synthesize it.

Question 2

A patient has megaloblastic anemia with normal serum folate but elevated homocysteine. Which nutrient deficiency best explains this?

Accepted Answer

Vitamin B12

Answer

Vitamin B12 deficiency causes megaloblastic anemia and elevated homocysteine because it is required for methionine synthase, which converts homocysteine to methionine.

Question 3

The thermic effect of food (TEF) contributes approximately what percentage of total daily energy expenditure?

Accepted Answer

5–10%

Answer

TEF accounts for approximately 5–10% of total daily energy expenditure, representing energy used to digest, absorb, and metabolize nutrients.

Question 4

Which dietary fiber fermented by gut bacteria produces the greatest amount of butyrate?

Accepted Answer

Resistant starch

Answer

Resistant starch is the primary substrate for butyrate production by colonic bacteria, making it particularly beneficial for colonocyte health.

Question 5

Scurvy results from vitamin C deficiency primarily because ascorbic acid is required for which enzymatic process?

Accepted Answer

Prolyl hydroxylase activity in collagen synthesis

Answer

Vitamin C acts as a cofactor for prolyl and lysyl hydroxylases, enzymes essential for hydroxylating collagen precursors, which is necessary for proper cross-linking and structural integrity.

(CDN) Certified Dietician Nutritionist Practice Test

(CDN) Certified Dietician Nutritionist Practice Test

CDN Nutritional Science & Dietetics 2