All Free Biology MCQs with Answers

• A. Hormone-receptor complex
• B. Feedback system
• C. Prostaglandin
• D. Exocrine gland

Explanation: A thermostat is indeed a good example of a feedback system. In a feedback system, a change in one parameter triggers a response that…

• A. Each gland secrete only one hormone
• B. Two hormones with opposite effects regulate certain things
• C. Only steroid hormones regulate important functions
• D. The pituitary gland regulate all the other glands

Explanation: There is a common mechanism in the endocrine system known as antagonistic control.

• A. Decrease production of that substance
• B. Increase production of that substance
• C. Increase the production of other substances
• D. Stop production of another substance

Explanation: Explanation for this question will be added soon!

• A. Adrenal medulla
• B. Testis
• C. Hypothalamus
• D. Pituitary

Explanation: The testes are the male gonads responsible for producing testosterone, the primary male sex hormone.The testes consist of many coiled…

• A. Adrenal
• B. Hypothalamus
• C. Pancreas
• D. Parathyroid

Explanation: The pancreas is crucial in diabetes mellitus because it produces insulin, which helps regulate blood sugar levels.

• A. Parathyroid
• B. Hypothalamus
• C. Pituitary
• D. Adrenal

Explanation: The adrenal glands, specifically the adrenal medulla (inner part), produce epinephrine (adrenaline) and norepinephrine (noradrenaline).

• A. 5 and 8
• B. 9 and 15
• C. 16 and 19
• D. 20 and 25

Explanation: 9 to 15 is the most common range for the onset of puberty. Girls usually start puberty between ages 8 and 13, while boys typically begin…

• A. FSH and LH
• B. Estrogens
• C. Androgens
• D. Testosterone and progesterone

Explanation: FSH and LH are produced by the anterior pituitary gland in the brain. In males, FSH stimulates the testes to produce sperm cells, while LH…

• A. Birth
• B. Fertilization
• C. Gastrulation
• D. Puberty

Explanation: Puberty is the stage of development during which adolescents reach sexual maturity and become capable of reproduction.

• A. Egg
• B. Sperm
• C. Secondary male characteristics
• D. All of the above

Explanation: Testosterone plays a significant role in the development and maintenance of secondary sexual characteristics in males, such as facial…

• A. Gametes
• B. Hormones
• C. Gonads
• D. Organs

Explanation: Gametes are specialized sex cells, such as sperm in males and eggs (ova) in females.

• A. One per day
• B. About 20 per year
• C. One between them each month
• D. 200 million at a time

Explanation: Each ovary typically takes turns releasing an egg every menstrual cycle, so while each ovary produce an egg every month and collectively…

• A. Scrotum
• B. Epididymis
• C. Seminiferous tubules
• D. Vas deferens

Explanation: Seminiferous tubules are the actual structures within the testes where sperm production, or spermatogenesis, occurs.

• A. To produce eggs
• B. To prepare the body to carry an embryo
• C. To deliver sperm
• D. To release eggs into the Fallopian tubes

Explanation: Delivering sperm is not a function of the female reproductive system. Sperm delivery is the role of the male reproductive system.

• A. Female reproductive system
• B. Endocrine system
• C. Nervous system
• D. Male reproductive system

Explanation: The male reproductive system is responsible for making and delivering sperm.

• A. Menstruation
• B. Luteal
• C. Ovulation
• D. All of these

Explanation: Menstruation is the phase where the uterine lining sheds, leading to vaginal bleeding.

• A. Day
• B. Week
• C. Month
• D. Year

Explanation: A menstrual cycle usually lasts about a month, although it can vary slightly from woman to woman.

• A. Corpus luteum to disintegrate
• B. Follicle to release a mature egg
• C. Uterine lining to detach from the uterus
• D. The lining of the uterus to disintegrate

Explanation: LH surge stimulates the mature follicle to rupture and release the egg during ovulation.

• A. Uterine lining thickens
• B. Estrogen level falls
• C. Progesterone level falls
• D. Egg is fertilized

Explanation: If the egg is fertilized, it implants itself into the uterine lining, which becomes thicker and more vascularized to support the growing…

• A. Two-celled embryo
• B. Solid ball of about 50 cells
• C. Blastocyst
• D. Fertilized egg

Explanation: Fertilized egg refers to the initial stage of development when a sperm cell fertilizes an egg cell, forming a single cell known as a…