In humans, where does fertilization of the oocyte normally take place?
Uterine tube
✓
Uterine fundus
Ovarian surface
Cervical canal
Correct Answer
Uterine tube
Sperm normally meet the ovulated oocyte in the distal part of the uterine tube, and the resulting zygote then travels toward the uterus. The uterine fundus is a common site of implantation, not fertilization. The ovarian surface is where ovulation releases the oocyte. The cervical canal is a passageway sperm swim through on the way to the tubes.
Category: Fertilization
Question 2
What is the process by which fluids of the female reproductive tract enhance sperm motility and thin the membrane over the sperm head?
Spermiogenesis
Capacitation
✓
Cleavage
Implantation
Correct Answer
Capacitation
Capacitation primes sperm inside the female tract so they can release acrosomal enzymes and penetrate the oocyte's coverings. Spermiogenesis is the maturation of spermatids into sperm within the testis. Cleavage is the series of mitotic divisions of the zygote. Implantation is the embedding of the blastocyst in the endometrium.
Category: Fertilization
Question 3
After the first sperm fuses with the oocyte, calcium-triggered exocytosis of granules destroys sperm receptors on the zona pellucida. What is this slow block to polyspermy called?
Acrosomal reaction
Fast block
Cortical reaction
✓
Decidual reaction
Correct Answer
Cortical reaction
In the cortical reaction, a rise in calcium causes cortical granules beneath the oocyte membrane to release their contents, which inactivate sperm receptors and harden the zona pellucida. The acrosomal reaction is the release of enzymes from the sperm head. The fast block is a rapid membrane depolarization caused by sodium entry. A decidual reaction is a change in endometrial tissue, not a block to extra sperm.
Category: Fertilization
Question 4
At ovulation, the secondary oocyte is arrested at which stage of meiosis?
Prophase I
Metaphase I
Anaphase II
Metaphase II
✓
Correct Answer
Metaphase II
The ovulated secondary oocyte pauses at metaphase II and completes meiosis only if a sperm penetrates it, releasing a second polar body. Prophase I is where primary oocytes are arrested from fetal life until puberty. Metaphase I is passed before ovulation, when the first polar body forms. Anaphase II occurs only after fertilization restarts meiosis.
Category: Fertilization
Question 5
Which part of the blastocyst develops into the embryo itself?
Inner cell mass
✓
Trophoblast
Blastocoel
Zona pellucida
Correct Answer
Inner cell mass
The inner cell mass is the cluster of cells inside the blastocyst that gives rise to the embryo. Trophoblast is the outer cell layer that forms the chorion and the fetal part of the placenta. Blastocoel is the fluid-filled cavity of the blastocyst. Zona pellucida is the glycoprotein shell the blastocyst hatches out of before implanting.
Category: Embryonic Development
Question 6
Which hormone is secreted by the trophoblast and keeps the corpus luteum producing progesterone in early pregnancy?
Luteinizing hormone
Human chorionic gonadotropin
✓
Follicle-stimulating hormone
Gonadotropin-releasing hormone
Correct Answer
Human chorionic gonadotropin
Human chorionic gonadotropin from the trophoblast rescues the corpus luteum so it keeps secreting progesterone and estrogen, and it is the hormone detected by pregnancy tests. Luteinizing hormone comes from the anterior pituitary and triggers ovulation. Follicle-stimulating hormone is a pituitary hormone that stimulates follicle growth. Gonadotropin-releasing hormone is made by the hypothalamus.
Category: Embryonic Development
Question 7
Which primary germ layer gives rise to the nervous system and the epidermis?
Endoderm
Mesoderm
Ectoderm
✓
Hypoblast
Correct Answer
Ectoderm
Ectoderm forms the central and peripheral nervous systems, the sensory organs, and the epidermis with its hair and nails. Endoderm forms the epithelial lining of the digestive tract and organs such as the liver, pancreas, and lungs. Mesoderm forms muscle, bone, connective tissue, the heart, blood vessels, and kidneys. Hypoblast is an early layer of the bilaminar disc that contributes to the yolk sac, not a primary germ layer.
Category: Embryonic Development
Question 8
In adults, remnants of the embryonic notochord persist as which structure?
Spinal cord
Vertebral bodies
Annulus fibrosus
Nucleus pulposus
✓
Correct Answer
Nucleus pulposus
The notochord is a mesodermal rod beneath the neural tube that guides development of the vertebral column, and its remnants become the nucleus pulposus at the center of each intervertebral disc. Spinal cord develops from the neural tube. Vertebral bodies form from surrounding mesoderm. Annulus fibrosus is the fibrocartilage ring of the disc, formed from surrounding mesoderm.
Category: Embryonic Development
Question 9
Two parents are both heterozygous carriers of a recessive disease allele. What is the probability that each of their children will be affected?
25%
✓
50%
75%
0%
Correct Answer
25%
A cross of two heterozygotes gives one homozygous dominant, two heterozygous, and one homozygous recessive outcome out of four, so each child has a 25% chance of being affected. A 50% chance is the probability that a child will be a carrier. A 75% chance is the probability that a child will show the dominant phenotype. A 0% chance would apply only if a parent had no recessive allele.
Category: Patterns of Inheritance
Question 10
Which vessel carries oxygen-rich blood from the placenta to the fetus?
Umbilical artery
Umbilical vein
✓
Ductus arteriosus
Pulmonary vein
Correct Answer
Umbilical vein
The single umbilical vein returns oxygenated, nutrient-rich blood from the placenta to the fetus. Umbilical artery refers to the paired vessels that carry deoxygenated blood and wastes from the fetus to the placenta. Ductus arteriosus is a shunt from the pulmonary trunk to the aorta. Pulmonary vein carries little blood in the fetus because the lungs are not yet used for gas exchange.
Category: Fetal Development
Question 11
Which fetal shunt lets oxygenated blood returning from the placenta bypass the liver?
Foramen ovale
Ductus arteriosus
Ductus venosus
✓
Umbilical artery
Correct Answer
Ductus venosus
The ductus venosus connects the umbilical vein to the inferior vena cava so that much of the oxygenated blood bypasses the immature liver. Foramen ovale is an opening between the right and left atria that bypasses the lungs. Ductus arteriosus moves blood from the pulmonary trunk into the aorta, also bypassing the lungs. Umbilical artery carries blood from the fetus to the placenta rather than acting as a shunt.
Category: Fetal Development
Question 12
Cystic fibrosis is inherited in which pattern?
Autosomal dominant
X-linked recessive
X-linked dominant
Autosomal recessive
✓
Correct Answer
Autosomal recessive
Cystic fibrosis is caused by a recessive allele on an autosome, so a person must inherit two copies to be affected, and carriers are usually healthy. Autosomal dominant describes disorders such as Huntington disease that need only one allele. X-linked recessive describes disorders such as hemophilia that mostly affect males. X-linked dominant describes rare disorders such as vitamin D-resistant rickets.
Category: Patterns of Inheritance
Question 13
Which hormone loosens the pelvic joints and ligaments and helps soften the cervix in preparation for birth?
Relaxin
✓
Progesterone
Prolactin
Cortisol
Correct Answer
Relaxin
Relaxin, produced by the corpus luteum and placenta, loosens the pubic symphysis and pelvic ligaments and helps the cervix dilate. Progesterone keeps the uterus quiet by inhibiting contractions. Prolactin stimulates milk production. Cortisol is an adrenal hormone; rising fetal cortisol late in pregnancy boosts placental estrogen but does not loosen ligaments.
Category: Pregnancy and Labor
Question 14
Which stage of labor is usually the longest?
Expulsion stage
Dilation stage
✓
Afterbirth stage
Involution stage
Correct Answer
Dilation stage
The dilation stage, in which the cervix thins and opens fully to 10 cm, typically lasts many hours and is usually shorter in later births. Expulsion stage is the delivery of the newborn and is much shorter. Afterbirth stage is delivery of the placenta and membranes, which normally takes minutes. Involution stage is not a stage of labor; involution is the shrinking of the uterus after birth.
Category: Pregnancy and Labor
Question 15
Which posterior pituitary hormone stimulates uterine contractions in a positive feedback loop during labor?
Prolactin
Progesterone
Oxytocin
✓
Relaxin
Correct Answer
Oxytocin
Stretch of the cervix triggers oxytocin release, oxytocin strengthens contractions, and stronger contractions stretch the cervix further, a classic positive feedback loop that ends with delivery. Prolactin is an anterior pituitary hormone that drives milk synthesis. Progesterone is a placental hormone that inhibits contractions. Relaxin loosens pelvic ligaments rather than causing contractions.
Category: Pregnancy and Labor
Question 16
In the adult heart, the remnant of the fetal opening between the right and left atria is the
Ligamentum arteriosum
Ligamentum venosum
Medial umbilical ligament
Fossa ovalis
✓
Correct Answer
Fossa ovalis
When the lungs inflate at birth, pressure in the left atrium rises above the right and closes the flaps of the foramen ovale, which later fuse to leave the fossa ovalis in the interatrial septum. Ligamentum arteriosum is the remnant of the ductus arteriosus. Ligamentum venosum is the remnant of the ductus venosus. Medial umbilical ligament is the remnant of an umbilical artery.
Category: Newborn Adjustments
Question 17
Newborns generate heat without shivering mainly by metabolizing which tissue?
Brown adipose tissue
✓
White adipose tissue
Skeletal muscle
Hepatic glycogen
Correct Answer
Brown adipose tissue
Brown adipose tissue over the back, chest, and shoulders is rich in mitochondria that release energy as heat rather than ATP, which is called nonshivering thermogenesis. White adipose tissue mainly stores energy and insulates. Skeletal muscle produces heat by shivering, which newborns do poorly. Hepatic glycogen is a glucose store, not a dedicated heat-producing tissue.
Category: Newborn Adjustments
Question 18
How many criteria are scored in the Apgar assessment of a newborn?
Three
Five
✓
Seven
Ten
Correct Answer
Five
The Apgar score rates five signs (skin color, heart rate, reflex response, muscle tone, and breathing) from 0 to 2 each at 1 and 5 minutes after birth. Three is too few to cover all five signs. Seven is too many for the five-sign score. Ten is the maximum total score, not the number of criteria.
Category: Newborn Adjustments
Question 19
Which anterior pituitary hormone stimulates the mammary glands to synthesize milk?
Oxytocin
Estrogen
Prolactin
✓
Relaxin
Correct Answer
Prolactin
Prolactin rises during pregnancy and spikes with each feeding afterward to drive milk production by the lactocytes. Oxytocin is released by the posterior pituitary and causes milk ejection rather than synthesis. Estrogen promotes breast growth during pregnancy but, with progesterone, inhibits milk production before birth. Relaxin acts on pelvic ligaments and the cervix.
Category: Lactation
Question 20
A person who inherits an IA allele and an IB allele has type AB blood because both alleles are fully expressed. What is this pattern of inheritance called?
Incomplete dominance
Polygenic inheritance
X-linked inheritance
Codominance
✓
Correct Answer
Codominance
Codominance means both alleles in a heterozygote are fully expressed, so a person with IA and IB makes both A and B antigens. Incomplete dominance produces an intermediate blend, as in pink snapdragons. Polygenic inheritance means several genes contribute to one trait, as with eye color. X-linked inheritance involves genes on the X chromosome, while the ABO gene is on an autosome.
Category: Patterns of Inheritance