Reproductive System Trivia
0Loading crowd target
0Loading crowd target
7correct to beat the crowd
99 free Reproductive System trivia questions with answers — science & nature quiz, new questions added Oct 2026.
This reproductive system trivia quiz covers the human reproductive system the way a biology or health class would: the female organs from ovary to cervix, the male organs from testis to urethra, the glands that add fluid to semen, and the hormones that run the whole show, from GnRH and FSH to estrogen, progesterone and testosterone. It also digs into the cell biology and development: meiosis and the 23-chromosome gamete, how one oocyte yields a single ovum while a spermatocyte yields four sperm, the Wolffian and Müllerian ducts, the week the embryo's sex is set, when the testes descend, and the 28-day cycle with its follicular and luteal phases. The opening questions suit a middle or high school review; the later ones reward anyone who has taken anatomy and physiology. Every answer was checked against encyclopaedia entries before publishing.
30 of 99 questions with answers and explanations. Play the quiz
Q 01Which temporary organ attaches to the wall of the uterus during pregnancy to supply the baby with oxygen and food?
The placenta
The placenta. It also carries the baby's waste away, and because it is delivered shortly after the baby, it is commonly known as the afterbirth.
Q 02What is the inner lining of the uterus, the layer shed during a period, called?
Endometrium
Endometrium. It thickens each cycle ready to receive an embryo, and if none implants only its upper layer is shed, leaving a deeper layer behind to rebuild it.
Q 03Shortly after an egg is released, sperm usually meet and fertilise it inside which structure?
Fallopian tube
Fallopian tube. The embryo normally drifts on to the uterus, and when it implants in the tube instead the result is an ectopic pregnancy, because the narrow tube cannot hold a growing embryo.
Q 04What is the narrow neck of the uterus, where it joins the vagina, called?
Cervix
Cervix. A plug of mucus keeps it sealed throughout pregnancy, then in labour it thins and opens to about 10 centimetres so the baby's head can pass through.
Q 05What is the first cell of a new human, formed when a sperm fertilises an egg, called?
Zygote
Zygote. Only one sperm gets in: the moment it fuses with the egg, the egg's outer coat changes to lock out all the others, and the new cell starts to divide.
Q 06What is the release of an egg cell from the ovary called?
Ovulation
Ovulation. A surge of hormone makes the ripe egg sac burst open, and some women feel it as a twinge low on one side of the belly, the side of the ovary that released the egg.
Q 07About how many days does a typical menstrual cycle last?
28
28 days is the average, and the word 'menstrual' fittingly comes from the Latin for month. Anything from 21 to 35 days still counts as a normal cycle.
Q 08A girl's first period is known as what?
Menarche
Menarche. It is not the opening act of puberty: it typically arrives around age 12, about two years after the breasts begin to develop.
Q 09Which hormone, rising through the first half of the cycle, makes the lining of the uterus thicken?
Estrogen
Estrogen. It rebuilds the lining after each period, and its peak just before the egg is released also thins the mucus that sperm must swim through.
Q 10Menstruation is triggered by falling levels of which hormone?
Progesterone
Progesterone. The emptied egg sac turns into a temporary gland that makes it to hold the lining in place; with no pregnancy the gland breaks down, the level drops and the lining is shed.
Q 11The hypothalamus in the brain sets the reproductive system in motion by releasing which hormone?
Gonadotropin-releasing hormone
Gonadotropin-releasing hormone, or GnRH. It runs low in childhood, and its rise at puberty is what switches the system on, prompting the pituitary to signal the ovaries or testes.
Q 12What does FSH, the hormone that ripens the egg-holding sacs in the ovaries each cycle, stand for?
Follicle-stimulating hormone
Follicle-stimulating hormone. Follicles are the small fluid-filled sacs that hold the eggs, yet men make this hormone too: in the testes it keeps sperm production going.
Q 13A surge of which pituitary hormone triggers the release of a mature egg?
Q 21Which cells, tucked between the sperm-making tubes of the testes, produce testosterone?
Leydig
Leydig cells. They get to work remarkably early: in a male embryo they are already releasing testosterone by about the seventh week of development, long before puberty.
Q 22Which 'nurse' cells inside the sperm-making tubes of the testes feed and shield developing sperm?
Sertoli
Sertoli cells. Sealed tightly to one another, they also wall developing sperm off from the bloodstream, because the immune system would otherwise treat those sperm as foreign.
Q 23Why do a man's testes hang outside his body?
To stay cooler
To stay cooler. Sperm form best a few degrees below body heat, so muscles in the scrotum pull the testes up close when it is cold and let them hang lower when it is warm.
Luteinizing hormone
Luteinizing hormone. Home fertility kits work by spotting this surge in urine a day or two before the egg appears, and in men the same hormone tells the testes to make testosterone.
Q 14How many chromosomes does a human egg or sperm cell carry, half the number found in other body cells?
23
23. Almost every other cell in the body holds 46, so when an egg and a sperm fuse the two half-sets add up to a full set again, half of it from each parent.
Q 15Which type of cell division halves the chromosome number to make eggs and sperm?
Meiosis
Meiosis. The cell copies its chromosomes once but then divides twice, which is why each egg or sperm ends up with only half the usual number.
Q 16What is the general term for the body's production of eggs and sperm?
Gametogenesis
Gametogenesis. The sexes run it at very different rates: a man turns out well over a hundred million sperm every day, while a woman typically releases a single egg a month.
Q 17When are all of a woman's eggs formed?
Before birth
Before birth. Every egg she will ever release is already in her ovaries when she is born, paused part-way through its development, and the stock only shrinks from then on.
Q 18An egg or sperm carries one set of chromosomes instead of the usual two, making it what kind of cell?
Haploid
Haploid. Ordinary body cells are diploid, with one set from each parent, and if eggs and sperm were too, the chromosome count would double with every generation.
Q 19Newly made sperm cannot yet swim, so in which tightly coiled tube behind each testis do they mature and gain that ability?
Epididymis
Epididymis. Uncoiled, this single tube would stretch about six metres, and sperm learn to swim on the slow trip through it; their tails are built earlier, inside the testis.
Q 20Sperm are produced in which fine coiled tubes inside the testes?
Seminiferous tubules
Seminiferous tubules. These tightly coiled tubes make up most of each testis, and from puberty onwards the cells lining them turn out sperm continuously for the rest of a man's life.
Q 24Which tube, also called the sperm duct, carries sperm toward the ejaculatory duct?
Vas deferens
Vas deferens. A vasectomy works by cutting and sealing this tube on each side, so a man still ejaculates as before but the fluid no longer carries any sperm.
Q 25Which pair of structures behind the bladder supplies most of the fluid that sperm travel in?
Seminal vesicles
Seminal vesicles. Their thick fluid is rich in the sugar fructose, which sperm burn as fuel for swimming, and it makes up more than half of what a man ejaculates.
Q 26The bulbourethral glands are also known by what other name?
Cowper's
They add fluid to semen during ejaculation.
Q 27A sperm carrying which chromosome results in a male child?
Y
Y. Every egg carries an X, so the father's sperm decides a baby's sex; in birds it runs the other way, with chromosomes called Z and W, and the mother's egg decides.
Q 28Which more potent hormone, which the body makes from testosterone, is linked to male-pattern baldness?
DHT
DHT, short for dihydrotestosterone. Before birth this same hormone is essential for forming a boy's external genitals, so its link to thinning hair only shows up decades later.
Q 29Which paired duct in the early embryo goes on to form the uterus and the upper part of the vagina?
Müllerian duct
Müllerian duct. Every early embryo has this pair and the Wolffian pair side by side; in a boy, a hormone from the newly formed testes makes the Müllerian ducts wither away.
Q 30Home pregnancy tests work by detecting which hormone in a woman's urine?
hCG
hCG, often called the pregnancy hormone. The embryo's outer cells start releasing it once they burrow into the wall of the uterus, which is why a test only becomes reliable around the first missed period.