Question 1

Which event prevents polyspermy (fertilization by more than one sperm) during human fertilization?

Accepted Answer

The release of $$Ca^{2+}$$ ions, which alters the zona pellucida

Question 2

During which stage does the human embryo first become a solid ball of cells, and what is this structure called?

Accepted Answer

Morula stage; morula

Question 3

Which embryonic germ layer gives rise to the nervous system and the epidermis?

Accepted Answer

Ectoderm

Question 4

A newborn is found to have an extra chromosome 21. Which process most likely failed during gamete formation?

Accepted Answer

Nondisjunction during meiosis

Question 5

Which fetal structure allows blood to bypass the liver and flow directly into the inferior vena cava?

Accepted Answer

Ductus venosus

Question 6

A woman is diagnosed with preeclampsia during pregnancy. Which of the following is NOT a classic sign of this condition?

Accepted Answer

Hyperglycemia

Question 7

Which hormone is responsible for maintaining the corpus luteum during early pregnancy and is detected in pregnancy tests?

Accepted Answer

Human Chorionic Gonadotropin (hCG)

Question 8

A male child inherits an X-linked recessive disorder from his mother. Which of the following best explains why males are more likely to express X-linked recessive traits?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed

Question 9

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygous phenotype is a blend of the two alleles

Question 10

A couple, both heterozygous for the PKU gene ($$Pp$$), are expecting a child. What is the probability their child will have PKU (autosomal recessive)?

Accepted Answer

$$\frac{1}{4}$$

Question 11

Which structure in the fetal circulation carries oxygenated blood from the placenta to the fetus?

Accepted Answer

Umbilical vein

Question 12

Which hormone is responsible for stimulating milk production in the mammary glands after birth?

Accepted Answer

Prolactin

Question 13

Which of the following is an example of a polygenic trait?

Accepted Answer

Skin color

Question 14

If a person has the genotype $$AB$$ for blood type, what is their phenotype?

Accepted Answer

Type AB

Question 15

Which process describes the formation of the three primary germ layers during embryonic development?

Accepted Answer

Gastrulation

Question 16

A woman with genotype $$X^H X^h ($$where $$X^H is $$normal and $$X^h is $$hemophilia) and a normal male ($$X^H Y) $$have a son. What is the probability that their son will have hemophilia?

Accepted Answer

$$\frac{1}{2}$$

Question 17

Which hormone increases the flexibility of the pubic symphysis and dilates the cervix during labor?

Accepted Answer

Relaxin

Question 18

Which of the following best describes the function of the foramen ovale in fetal circulation?

Accepted Answer

It diverts blood from the right atrium to the left atrium, bypassing the lungs

Question 19

Which of the following is true regarding the inheritance of Huntington's disease?

Accepted Answer

It is inherited in an autosomal dominant pattern

Question 20

Which structure forms the fetal part of the placenta and secretes hCG?

Accepted Answer

Trophoblast (chorionic villi)

Development and Inheritance

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