Enforcement Officer / Accounts Officer (EO/AO) 2020 recruitment test, advertisement 421. Transcribed from the Commission's own booklet (series A, NMJX-U-GTA); answer as per the official UPSC final answer key. This question is in Part B. Answer last reviewed 24 August 2026.

Which one of the following is not a female reproductive organ in humans ?

(a)Ovaries
(b)Oviducts
(c)Cervix
(d)Stamen

Answer

Why

Correct — D, (d) Stamen. The stamen is not a human organ at all — it is the male reproductive structure of a FLOWER, made of an anther that produces pollen sitting on a stalk called the filament. The question emphasises 'not' in bold italic, so it is asking for the odd one out, and the odd one out here is odd on two counts at once: the stamen belongs to a different kingdom, and within its own kingdom it is the male part, not the female one. The other three are all points on the human female reproductive tract, taken in the order an egg travels: the ovary makes and releases the ovum, the oviduct carries it and is where fertilisation happens, and the cervix is the narrow neck of the uterus opening into the vagina. A candidate who knows only that the flower's female part is called the carpel or pistil can answer this without knowing any human anatomy, because the stamen is its opposite number.

Why the others are wrong

(a)Ovaries — The ovaries ARE female reproductive organs, so this cannot be the answer to a question asking which one is not. A woman has a pair of them, one on each side of the lower abdomen. They are the primary sex organs: they hold the oocytes present from birth, release one mature ovum in most menstrual cycles, and secrete oestrogen and progesterone, which drive the secondary sexual characters and the cycle itself. The word is worth pausing on, because flowering plants also have an 'ovary' — the swollen base of the carpel that becomes the fruit — and the shared name is what makes this option feel like a trap when it is not one.
(b)Oviducts — The oviducts are female reproductive organs. They are the paired tubes better known as the fallopian tubes or uterine tubes, roughly 10 to 12 cm long, running from near each ovary to the uterus. The funnel-shaped fimbriated end sweeps the released ovum in, and fertilisation normally takes place in the wider ampulla of the tube rather than in the uterus; the embryo then travels down to implant in the uterine wall. The name is less familiar than 'fallopian tube', which is the only thing that makes this option tempting.
(c)Cervix — The cervix is a female reproductive organ — the narrow lower neck of the uterus that projects into the vagina. It is not a separate organ bolted on but the constricted end of the uterus itself, and its canal is the passage sperm must cross and through which a baby is delivered. Because a student may have met the word only in the phrase 'cervical cancer' rather than in a list of reproductive organs, it can read as something clinical rather than anatomical, which is the whole reason it is offered here.

Concept

The human female reproductive system is built as a continuous tract, and the cleanest way to hold it is to follow the ovum along it. A pair of OVARIES, the primary sex organs, sit in the pelvic cavity and release one secondary oocyte per cycle. The fimbriae at the mouth of each OVIDUCT (fallopian tube) catch it; fertilisation occurs in the ampulla of that tube. The tube delivers the zygote to the UTERUS, a thick muscular pear-shaped organ whose inner lining, the endometrium, is what builds up and is shed each month. The uterus narrows into the CERVIX, whose canal opens into the VAGINA. Everything on that list is human. The STAMEN sits in a completely different story: in an angiosperm flower the stamen is the male whorl (androecium) — anther plus filament, producing pollen — and the female whorl is the carpel or pistil (gynoecium), made of stigma, style and ovary. So the stamen is not merely non-human, it is the male part, which is what makes it a doubly clean answer here.

This opens the five-item biology block of Part B, and it is deliberately the easiest item in it. What the Commission is testing is whether a candidate reads the emphasised negation and then scans the list for the outlier rather than checking each option in turn against a half-remembered diagram. The habit that earns the mark is noticing that one option comes from a different syllabus altogether — botany sitting in a human-physiology list — because on a general ability paper that mismatch is almost always the intended answer. The reverse item is just as common: a list of flower parts with one human organ dropped in.

Key facts

The stamen is the male reproductive part of a flower — anther (pollen-producing) plus filament (stalk); all the stamens together form the androecium.
The female part of a flower is the carpel or pistil, made of stigma, style and ovary; all the carpels together form the gynoecium.
Human female reproductive organs in tract order: ovaries, oviducts (fallopian tubes), uterus, cervix, vagina.
The ovaries are the primary female sex organs — they produce ova and secrete oestrogen and progesterone.
Fertilisation in humans normally occurs in the ampulla of the oviduct, not in the uterus.
The cervix is the narrow lower neck of the uterus, not an organ separate from it.
'Ovary' is used in both botany and human anatomy for different structures, which is why a list can mix the two and still read smoothly.

Follow the ovum along the tract — and notice what belongs to another kingdom

Stamen→Not a human organ at all — the male reproductive structure of a FLOWER, an anther that produces pollen sitting on a stalk called the filament. It is odd on two counts at once: it belongs to a different kingdom, and within its own kingdom it is the male part rather than the female one.

Ovaries→The primary female sex organs — a pair in the pelvic cavity, holding the oocytes present from birth, releasing one mature ovum in most menstrual cycles, and secreting oestrogen and progesterone, which drive the secondary sexual characters and the cycle itself.

Oviducts→The paired fallopian or uterine tubes, roughly 10 to 12 cm long, running from near each ovary to the uterus. The funnel-shaped fimbriated end sweeps the released ovum in, and fertilisation normally takes place in the wider ampulla of the tube rather than in the uterus.

Cervix→The narrow lower neck of the uterus, projecting into the vagina — not a separate organ bolted on but the constricted end of the uterus itself. Its canal is the passage sperm must cross and through which a baby is delivered.

The flower’s two whorls→All the stamens together form the ANDROECIUM, the male whorl. The female whorl is the carpel or pistil, the GYNOECIUM, made of stigma, style and ovary. A candidate who knows only that much can answer this item without any human anatomy, because the stamen is the carpel’s opposite number.

Why the list reads smoothly→‘Ovary’ is used in both botany and human anatomy for quite different structures, which is what lets an examiner mix the two vocabularies in one option set without the seam showing.

Study next

The human male reproductive system — testes, epididymis, vas deferens, seminal vesicles, prostate, urethraThe menstrual cycle and the hormones that run it: FSH, LH, oestrogen and progesteroneParts of a flower and the four whorls — calyx, corolla, androecium, gynoeciumPollination, fertilisation and double fertilisation in flowering plantsGametogenesis: oogenesis and spermatogenesis compared

Common traps

Missing the emphasised 'not' and picking the first option that IS a female organ. Every option except the answer is one.
Confusing the botanical ovary with the human ovary because they share a name.
Swapping stamen and carpel — stamen is male, carpel or pistil is female. Mixing the two turns this question into a coin toss.
Reading 'cervix' as a disease term rather than an anatomical one and rejecting it for being unfamiliar in this list.
Assuming 'oviduct' must be something non-human because the familiar name is 'fallopian tube'.

The biology block on EPFO EO/AO papers stays at school level and favours single-fact recall over reasoning. Odd-one-out items like this one are the commonest shape, usually with the outlier taken from a neighbouring topic — a plant structure in an animal list, an animal structure in a plant list, or an excretory organ among reproductive ones. Direct 'which organ does what' items and 'where does fertilisation occur' items come from the same syllabus corner.

Related PYQs

EPFO_EOAO_2020_Q42Open & attempt →

Which one of the following cannot be called “Amphibian of the Plant Kingdom” ?

(a) Spirogyra
(b) Riccia
(c) Funaria
(d) Marchantia

Answer(a) Spirogyra

The next item in the same biology block, and built the same way — a list of plant genera with one that does not belong to the group the phrase in the stem names. Both reward finding the outlier rather than verifying each option.

Practice

practice — not a real PYQ
Which one of the following is the female reproductive part of a flower ?
- (a)Stamen
- (b)Anther
- (c)Carpel
- (d)Filament
Answer(c) Carpel
practice — not a real PYQ
In humans, fertilisation of the ovum normally takes place in the
- (a)ovary
- (b)ampulla of the oviduct
- (c)uterus
- (d)cervix
Answer(b) ampulla of the oviduct

Why