Unit 8 Sex Determination

Question 1

Which gene initiates male sex determination?
a) DAX1
b) SRY
c) AMH
d) WNT4

Answer 1

b) SRY

Explanation: The SRY gene on the Y chromosome directs the undifferentiated gonad to develop into a testis.

Question 2

What happens in the absence of SRY and AMH?
a) Male development proceeds by default
b) Testes develop
c) Müllerian ducts form uterus and fallopian tubes
d) Wolffian ducts become dominant

Answer 2

c) Müllerian ducts form uterus and fallopian tubes

Explanation: Female development occurs by default unless overridden by SRY and AMH signals.

Question 3

What does anti-Müllerian hormone (AMH) do in male fetal development?
a) Causes regression of Müllerian ducts
b) Promotes testis formation
c) Stimulates ovarian development
d) Induces testosterone synthesis

Answer 3

a) Causes regression of Müllerian ducts

Explanation: AMH is secreted by Sertoli cells and eliminates the female duct system.

Question 4

Which hormone is responsible for development of male internal genitalia (epididymis, vas deferens, seminal vesicles)?
a) Estrogen
b) AMH
c) DHT
d) Testosterone

Answer 4

d) Testosterone

Explanation: Testosterone supports development of the Wolffian duct into male internal reproductive structures.

Question 5

What role does DHT play in fetal development?
a) Maintains Wolffian ducts
b) Promotes development of external male genitalia
c) Regresses Müllerian ducts
d) Forms prostate only

Answer 5

b) Promotes development of external male genitalia

Explanation: DHT, converted from testosterone via 5α-reductase, is critical for penis, scrotum, and prostate development.