sexual-reproduction-in-flowering-plants MCQs for UPSC Prelims

26 practice questions on sexual-reproduction-in-flowering-plants from the Reproduction: How Life Continues section of the UPSC Prelims syllabus. 26 come with a written explanation. Try the sample set below - the answer stays hidden until you ask for it.

8 Easy 13 Medium 5 Hard

Sample questions

Q1
hard
Measurements show that a wind-pollinated grass releases about 5,00,000 to 10,00,000 pollen grains per flower but forms only about 50 to 200 seeds, while an insect-pollinated sunflower releases about 20,000 to 40,000 pollen grains and forms about 800 to 1,000 seeds. What does this comparison show?
  1. A Sunflower pollen grains must be lighter than grass pollen grains
  2. B Insect pollination delivers pollen to stigmas far more efficiently, so far fewer grains are needed per seed formed
  3. C Wind pollination delivers pollen more efficiently, since far more pollen is released
  4. D Wind-pollinated plants form more seeds than insect-pollinated plants do
Show answer and explanation

Correct answer: B - Insect pollination delivers pollen to stigmas far more efficiently, so far fewer grains are needed per seed formed

The grass spends thousands of pollen grains for each seed, while the sunflower spends only a few tens, so an insect carrying pollen straight from flower to flower wastes far less. Releasing more pollen is a sign of waste, not of efficiency. The data say nothing about pollen weight, and in fact the insect-pollinated sunflower forms the larger number of seeds.
Q2
medium
Assertion (A): In many flowers the stigma is flat and sticky. Reason (R): The stigma is the part of the flower inside which the ovules are formed.
  1. A Both A and R are true, and R is the correct explanation of A
  2. B Both A and R are true, but R is not the correct explanation of A
  3. C A is true, but R is false
  4. D A is false, but R is true
Show answer and explanation

Correct answer: C - A is true, but R is false

(A) is true, as a flat, sticky stigma is common and helps it hold on to pollen grains that land on it. (R) is false, because ovules are formed inside the ovary at the base of the pistil, not in the stigma. Since (R) is untrue, it cannot serve as an explanation.
Q3
medium
Assertion (A): A flower whose stigma never receives any pollen does not form a fruit. Reason (R): An ovary grows into a fruit only after a male gamete has fused with the egg cell inside an ovule.
  1. A Both A and R are true, and R is the correct explanation of A
  2. B Both A and R are true, but R is not the correct explanation of A
  3. C A is true, but R is false
  4. D A is false, but R is true
Show answer and explanation

Correct answer: A - Both A and R are true, and R is the correct explanation of A

(A) is true: with no pollen on the stigma there is no pollen tube, no fertilisation and no fruit, as bagging experiments on pea flowers show. (R) is true as well, since the ovary enlarges into a fruit only once fertilisation has occurred. The requirement stated in (R) is exactly why (A) happens, so (R) explains (A).
Q4
easy
A stamen is made of two parts. Which are they?
  1. A A filament and an anther
  2. B A stigma and a style
  3. C A sepal and a petal
  4. D An ovary and an ovule
Show answer and explanation

Correct answer: A - A filament and an anther

A stamen consists of a filament, the stalk, and an anther at its top. Stigma and style belong to the pistil, the female part of the flower. Sepals and petals are the outer whorls of the flower, and the ovary with its ovules lies at the base of the pistil.
Q5
easy
Which part of a flower produces pollen grains?
  1. A The sepal
  2. B The ovary
  3. C The anther
  4. D The stigma
Show answer and explanation

Correct answer: C - The anther

Pollen grains, which carry the male gametes, are produced in the anther of a stamen. The stigma is the tip of the pistil, where pollen is received rather than made. The ovary holds the ovules with their egg cells, and the sepal is the green covering that protects the flower bud.
Q6
medium
Assertion (A): A pea flower bud that is wrapped in a muslin bag before it opens can still go on to form a pod. Reason (R): Pollination is the transfer of pollen grains from an anther to a stigma.
  1. A Both A and R are true, and R is the correct explanation of A
  2. B Both A and R are true, but R is not the correct explanation of A
  3. C A is true, but R is false
  4. D A is false, but R is true
Show answer and explanation

Correct answer: B - Both A and R are true, but R is not the correct explanation of A

(A) is true, because the pea flower's own anthers shed pollen on to its own stigma while the bud is still closed. (R) is also true, since that is what pollination means. But the definition alone does not say why a sealed bud manages to be pollinated; that comes from self-pollination happening inside the closed bud, so (R) does not explain (A).
Q7
medium
A student removes all the stamens from a young flower bud and then covers the bud with a muslin bag. Which cells will that flower now be unable to supply for itself?
  1. A Both kinds of gamete, because a stamen makes both of them
  2. B Its own female gametes, because egg cells are made in the anthers
  3. C Its own male gametes, because pollen is made in the anthers of the stamens
  4. D Neither kind, because gametes are made in the sepals
Show answer and explanation

Correct answer: C - Its own male gametes, because pollen is made in the anthers of the stamens

The anthers on the stamens make the pollen that carries the male gametes, so removing the stamens leaves the flower with no male gametes of its own. Egg cells are made in the ovules inside the ovary, which is untouched, so the female gametes remain. A stamen makes only pollen, and sepals make no gametes at all.
Q8
medium
The flowers of sunflower, hibiscus and marigold are brightly coloured, give off a fragrance and produce nectar, and their pollen grains are large and sticky. Which pollinating agent do these features suit?
  1. A The wind
  2. B Water currents
  3. C Insects such as bees and butterflies
  4. D Gravity alone
Show answer and explanation

Correct answer: C - Insects such as bees and butterflies

Colour, scent and nectar all advertise the flower to visiting insects, and large sticky pollen clings to an insect's body and is carried to the next flower. Wind-pollinated flowers are dull and scentless and shed light, dry pollen instead. Water carries pollen only for aquatic plants, and gravity alone would drop pollen straight down and move it nowhere.

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