Sexual Reproduction in Flowering Plants — Class 12 MCQs with Answers

Sexual Reproduction in Flowering Plants — important questions & MCQs with answers (Class 12 Biology)

6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.

0 of 6 answered

1. Q1 of 6Easy

   Male reproductive part of flower:

   APetalBCarpelCSepalDStamen
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   Answer: Stamen

   Explanation: The stamen is the flower's male whorl (androecium), made of a filament and a pollen-bearing anther; the carpel (gynoecium) is the separate female part — don't swap the two whorls.

2. Q2 of 6Easy

   Pollination by wind is:

   AAnemophilyBHydrophilyCEntomophilyDOrnithophily
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   Answer: Anemophily

   Explanation: Anemophily is wind pollination, relying on light, dry, non-sticky pollen produced in huge amounts; entomophily (insects) and hydrophily (water) use very different pollen adaptations, so don't confuse the terms.

3. Q3 of 6Medium

   Microspore mother cell undergoes ___ to give pollen.

   AMeiosisBMitosis onlyCNo divisionDBinary fission
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   Answer: Meiosis

   Explanation: The diploid microspore mother cell undergoes meiosis (reduction division), producing a tetrad of four haploid microspores that mature into pollen — mitosis alone could not halve the chromosome number.

4. Q4 of 6Medium

   Double fertilisation in angiosperms produces:

   ATwo zygotesBZygote and primary endosperm nucleusCTwo endospermsDSingle embryo only
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   Answer: Zygote and primary endosperm nucleus

   Explanation: Double fertilisation gives two distinct products: syngamy (sperm + egg) forms the diploid zygote, and triple fusion (sperm + two polar nuclei) forms the triploid primary endosperm nucleus — not two zygotes or two endosperms.

5. Q5 of 6Hard

   Apomixis is:

   AAsexual reproduction mimicking sexual seed formationBCross-pollinationCSelf-pollinationDVegetative budding only
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   Answer: Asexual reproduction mimicking sexual seed formation

   Explanation: Apomixis is asexual reproduction that produces seeds without fertilisation, so the embryo is a genetic clone of the parent; it's valuable in hybrid seed production because it locks in hybrid vigour across generations without repeated crossing.

6. Q6 of 6Hard

   Endosperm in angiosperms is:

   ADiploidBTriploid (3n)CHaploidDTetraploid
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   Answer: Triploid (3n)

   Explanation: Endosperm is triploid (3n) because triple fusion joins the two haploid polar nuclei of the central cell with one haploid sperm; the zygote from the separate syngamy event is only 2n — mixing up which fusion gives which ploidy is the classic slip.

Sexual Reproduction in Flowering Plants notes: key concepts (Class 12 Biology)

Reproduction in flowering plants: the stamen and pistil, microsporogenesis and megasporogenesis building the male and female gametophytes, pollination and its outbreeding devices, the double fertilisation unique to angiosperms, and the post-fertilisation making of seed, endosperm and fruit.

Microsporogenesis

Formation of haploid microspores from a diploid microspore mother cell by meiosis; each MMC gives a tetrad of four microspores inside the anther.

Tapetum

Innermost nutritive wall layer of the microsporangium; nourishes developing pollen and supplies sporopollenin. Its cells are often multinucleate/polyploid.

Pollen grain

The male gametophyte; wall has a durable outer exine of sporopollenin (with germ pores) and inner intine. Mostly shed at the 2-celled (vegetative + generative) stage.

Megasporogenesis

Formation of megaspores from a diploid megaspore mother cell by meiosis; a linear tetrad forms and usually only one chalazal megaspore stays functional.

Embryo sac

The female gametophyte, monosporic and 7-celled/8-nucleate: one egg, two synergids, three antipodals and a central cell with two polar nuclei.

Filiform apparatus

Special thickenings at the micropylar tip of the synergids that guide the entering pollen tube into the embryo sac toward the egg.

Pollination

Transfer of pollen to a stigma: autogamy (same flower), geitonogamy (same plant, genetically self) and xenogamy (different plant, a genetic cross).

Outbreeding devices

Features promoting cross-pollination: dichogamy (protandry/protogyny), self-incompatibility, herkogamy and unisexuality to prevent self-pollination.

Double fertilisation

Two male gametes act in one embryo sac: syngamy (gamete + egg → 2n zygote) and triple fusion (gamete + two polar nuclei → 3n PEN). Unique to angiosperms.

Endosperm

Triploid (3n) nutritive tissue from the primary endosperm nucleus; feeds the embryo. Persists in albuminous seeds (castor), used up in non-albuminous (pea).

Post-fertilisation events

The zygote becomes the embryo, the ovule the seed and the ovary wall the pericarp of the fruit; the integuments harden into the seed coat.

Parthenocarpy

Development of a fruit without fertilisation, giving seedless fruit (e.g., banana); can be induced by applying growth hormones.

Apomixis

Formation of seeds without fertilisation, a form of asexual reproduction; valuable in the hybrid seed industry as it keeps hybrid vigour over generations.

Emasculation

Removal of anthers from a bisexual flower bud before dehiscence in plant breeding; the bud is then bagged to stop unwanted cross-pollination.