All Free Biology MCQs with Answers

• A. Blastocyst is already present
• B. Egg in the Fallopian tubes
• C. Woman is menstruating
• D. All of the above

Explanation: Fertilization typically occurs in the fallopian tubes when sperm meets an egg.

• A. Sperm must swim into a Fallopian tube
• B. An egg must be present in the Fallopian tube
• C. An egg must be present in the oviduct
• D. All of the above

Explanation: Sperm need to swim from the vagina through the cervix, into the uterus, and then into the fallopian tubes where fertilization typically…

• A. The sperm's nucleus enters the egg cell
• B. Enzymes break down the protective layer of the egg cell membrane
• C. A sperm attaches to a binding site on the egg cell membrane
• D. The cell membrane of the egg cell changes

Explanation: The first step of fertilization where the sperm recognizes and binds to specific receptors on the egg cell membrane.

• A. Fallopian tube
• B. Ovary
• C. Uterus
• D. Vagina

Explanation: Fertilization typically occurs in the fallopian tube. After ovulation, the egg is released from the ovary and travels down the fallopian…

• A. A blastocyst
• B. A zygote
• C. The amnion
• D. Germ layers

Explanation: The correct answer is germ layers. Gastrulation leads to the formation of the three primary germ layers: ectoderm, mesoderm, and endoderm.

• A. Endoderm
• B. Ectoderm
• C. Mesoderm
• D. All of the above

Explanation: All three germ layers - endoderm, ectoderm, and mesoderm - are formed during gastrulation.

• A. Gastrulation
• B. Implantation
• C. Fertilization
• D. Ovulation

Explanation: Gastrulation is a process that occurs after implantation, where the blastocyst undergoes further developmental changes, leading to the…

• A. Mixing the blood of the mother and the fetus
• B. Protecting the fetus from any drugs or alcohol in the mother's body
• C. Providing nutrients to the fetus
• D. Cushioning and protecting the fetus

Explanation: One of the primary functions of the placenta is to provide essential nutrients, such as oxygen, glucose, amino acids, and fatty acids, to…

• A. Fetus to the mother's uterus
• B. Ectoderm to the endoderm
• C. Umbilical cord to the mother's vagina
• D. Uterus to the cervix

Explanation: The placenta is a temporary organ that develops during pregnancy and connects the fetus to the mother's uterus.

• A. Puberty
• B. Adulthood
• C. Adolescence
• D. Childhood

Explanation: Childhood typically refers to the period of life between infancy and adolescence.

• A. A growth spurt
• B. Secondary sex characteristics
• C. Puberty
• D. The appearance of first permanent teeth

Explanation: The appearance of the first permanent teeth typically occurs during childhood, not specifically during adolescence.

• A. Seminal vesicles and prostate
• B. Seminal vesicles and seminiferous tubules
• C. Seminiferous tubules and epididymis
• D. Bulbourethral glands and prostate

Explanation: Seminal vesicles and the prostate gland contribute the majority of seminal fluid (seminal plasma) in semen.

• A. Testes
• B. Seminal vesicles
• C. Prostate
• D. Vas deferens

Explanation: The prostate gland is an exception. There is only one prostate gland in the male reproductive system.

• A. Spermatozoa
• B. Testosterone
• C. GnRH
• D. All of these

Explanation: Spermatozoa, or sperm cells, are produced by the male reproductive organs called the testes.

• A. Follicles
• B. Secondary oocyte
• C. Corpus luteum
• D. Corpus albicans

Explanation: Secondary oocytes are indeed produced by the ovaries and they do not technically leave the ovaries until they are ovulated.

• A. Begin the development of the follicle
• B. Causes menstrual pain
• C. Stimulate release of secondary oocyte (ovulation)
• D. Stimulate corpus luteum to secrete estrogen and progesterone

Explanation: LH surge triggers ovulation, causing the release of the secondary oocyte from the mature follicle.

• A. Decreased FSH secretion
• B. Decreased LH secretion
• C. Absence of chorionic gonadotropin
• D. Decreased secretion of progesterone and estrogen by corpus luteum

Explanation: Menstruation occurs when the corpus luteum regresses due to decreased secretion of progesterone and estrogen.

• A. Sustentacular cells
• B. Interstitial cells
• C. Spermatogonia
• D. Granulosa cells

Explanation: Spermatogonia are the stem cells of spermatogenesis. They are located on the basement membrane of the seminiferous tubules and undergo…

• A. The second meiotic division occurs to produce an ovum
• B. The oocyte will be shed through the oviduct, uterus and vagina
• C. Conception will be delayed several days
• D. Implantation will indefinitely delayed

Explanation: After fertilization, the secondary oocyte completes its second meiotic division to become a mature ovum (egg).

• A. 400,000
• B. 400
• C. 4
• D. 1

Explanation: One is the correct answer. Each oogonium containing 46 chromosomes ultimately produces one mature fertilizable ovum through the process of…