10 USMLE Physiology and Biochemistry Quick Review Questions with Answers (Set 1)

These 10 quick USMLE review questions test the high-yield facts that show up again and again on the exam: athlete physiology, apolipoproteins, the menstrual cycle, adrenal insufficiency, p53 and the cell cycle, ovarian cells, 5-alpha reductase, vitamin D, fat-soluble vitamins and DNA base pairing. Each question includes the correct answer.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. Which of the following is higher in athletics than in non-athletics in resting conditions?

A- Cardiac output
B- Heart rate
C- Oxygen consumption
D- Stroke volume

D- Stroke volume
The correct answer is D

 

Question 2. Which one of the following apoproteins is associated with chylomicrons?

A- Apo A
B- Apo B-48
C- Apo C-II
D- Apo D
E- Apo E

B- Apo B-48
The correct answer is B

 

Question 3. Proliferation of endometrial glands results from stimulation by which one of the following hormones?

A- Androgen
B- Estrogen
C- Follicle-stimulating hormone
D- Progesterone

B- Estrogen
The correct answer is B

 

Question 4. Adrenal insufficiency is commonly combined with which one of the following findings?

A- Hypercalcemia
B- Hyperglycemia
C- Hyperkalemia
D- Hypernatremia

C- Hyperkalemia
The correct answer is C

 

Question 5. Which one of the following phases of the cell cycle is affected by binding p53 to DNA?

A- G0
B- G1
C- G2
D- M

B- G1
The correct answer is B

 

Question 6. Which of the following cells of the ovary secretes inhibin, follistatin and activin?

A- Granulosa cells
B- Surface epithelial cells
C- Theca externa cells
D- Theca interna cells

A- Granulosa cells
The correct answer is A

 

Question 7. Which one of the following enzymes catalyzes the transformation of testosterone into DHT?

A- 17α-hydroxylase
B- 5 α-reductase
C- Aromatase
D- Cholesterol side chain cleavage enzyme (CYP11A1)

B- 5 α-reductase
The correct answer is B

 

Question 8. Which of the following is the active form of vitamin D?

A- 1-dihydroxycholecalciferol
B- 1,25-dihydroxycholecalciferol
C- 25-hydroxycholecalciferol
D- Cholecalciferol

B- 1,25-dihydroxycholecalciferol
The correct answer is B

 

Question 9. Which one of the following is a fat-soluble vitamin?

A- Ascorbic acid
B- Retinoid
C- Riboflavin
D- Thiamine

B- Retinoid- Retinoids (Vitamin A) are fat-soluble vitamins. Ascorbic acid (Vitamin C), Riboflavin (B2), and Thiamine (B1) are all water-soluble vitamins.
The correct answer is B

 

Question 10. Which of the following is the percentage of thymine in a dsDNA if it contains 20% guanine?

A- 20%
B- 30%
C- 40%
D- 50%

B- 30%- In double-stranded DNA:
G pairs with C, so if G = 20%, then C = 20%.
That accounts for 40% of the bases.
The remaining 60% must be A + T, and since A = T, each is 30%.
The correct answer is B

 

High-yield points from this set

  • Athletes have a higher resting stroke volume and lower heart rate.
  • Chylomicrons carry apolipoprotein B-48.
  • Adrenal insufficiency causes hyperkalemia and hyponatremia.
  • Chargaff rule: A = T and G = C in double-stranded DNA.

Keep practicing

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