UKPSC Prelims 2025 General Studies Paper-I · Question 35 of 149

Correct — C, Plumule – Root tip.

Plumule – Root tip is the pairing that breaks. The plumule is the embryonic shoot: it lies on the embryonal axis above the cotyledons and grows upward into the stem and leaves.

The other end is the radicle. In the standard NCERT description the hypocotyl terminates at its lower end in the radicle, or root tip — the term belongs to the radicle, so the option attaches it to the wrong end of the seedling.

Carry one line away: the embryonal axis has the radicle at the root end and the plumule at the shoot end. The remaining three pairs are each defensible as stated, so they survive a "NOT correctly matched" stem.

• (a)
  Fertilization – Gametes — This pairing holds, so it is not what a "NOT correctly matched" stem is hunting for. Fertilisation, or syngamy, is the fusion of a male and a female gamete to give a diploid zygote.

  The pair is what you would tick for the definition of fertilisation as the fusion of two gametes.

• (b)
  Triple Fusion – Double fertilization — This pairing also holds. In a flowering plant one male gamete fuses with the egg to form the zygote, while the second fuses with the two polar nuclei — that second event is triple fusion.

  Triple fusion on its own is what yields the triploid primary endosperm nucleus. Double fertilisation names both fusions taken together, so triple fusion sits inside it rather than against it.

  The pair is the right answer to which fusion is one half of double fertilisation.

• (d)
  Embryo sac – Female gametophyte — This pairing holds too. The embryo sac is the haploid, gamete-bearing generation that develops inside the ovule and carries the egg cell.

  It lies within sporophytic ovule tissue, which can make it read as merely a part of the ovule, but its own identity is gametophytic.

  The pair answers what the female gametophyte of an angiosperm is — the counterpart of the pollen grain on the male side.

A seed's embryo is a miniature axis with a fixed polarity. One end, the radicle, is the embryonic root; the other end, the plumule, is the embryonic shoot; the cotyledons are attached between them.

The segment of that axis above the cotyledons and ending in the plumule is the epicotyl; the segment below the cotyledons and ending in the radicle is the hypocotyl. On germination the radicle emerges first and the plumule follows.

Plant reproduction supplies the rest of the vocabulary in this item. Fertilisation is gamete fusion, the embryo sac is the angiosperm female gametophyte, and triple fusion is one of the two fusions that make up double fertilisation.

• The radicle is the embryonic root of a seed and grows into the root system on germination.
• The plumule is the embryonic shoot and grows into the stem and leaves.
• The epicotyl is the part of the embryonal axis above the cotyledons, ending in the plumule.
• The hypocotyl is the part of the embryonal axis below the cotyledons, ending in the radicle.
• Fertilisation, or syngamy, is the fusion of a male and a female gamete to form a diploid zygote.
• In angiosperms one male gamete fuses with the egg and the other with the two polar nuclei; both events together are called double fertilisation.
• Triple fusion gives the triploid primary endosperm nucleus, from which the endosperm develops.
• The embryo sac is the female gametophyte of a flowering plant and develops inside the ovule; a typical mature embryo sac is seven-celled and eight-nucleate.
• The pollen grain is the male gametophyte of a flowering plant.
• In many monocot seeds the radicle is sheathed by a coleorhiza and the plumule by a coleoptile.

• The stem asks for the pair that is NOT correctly matched, so a pairing that reads as sound is a reason to reject that option rather than to select it.
• Plumule and radicle sit at opposite ends of one axis; holding on to "both are parts of the embryo" leaves the shoot-versus-root direction undecided.
• Triple fusion is a component of double fertilisation, not a competing process, so reading the pair as two rival names makes a sound option look broken.
• "Root tip" sounds anatomically specific, which can lend the pairing an air of precision even though the root end of the embryo is the radicle.
• In many monocot (grass) seeds the coleoptile sheathes the plumule and the coleorhiza the radicle; swapping those two sheaths reverses the same shoot–root axis.

• practice — not a real PYQ

  In the embryo of a dicot seed, the portion of the embryonal axis that lies below the cotyledons and ends in the radicle is called the

  • (a)Epicotyl
  • (b)Hypocotyl
  • (c)Plumule
  • (d)Coleorhiza
  Answerb — Hypocotyl.

  The hypocotyl is the segment of the embryonal axis below the cotyledons, terminating in the radicle.

  The epicotyl is the segment above the cotyledons, terminating in the plumule, so (a) names the opposite half. The plumule is the embryonic shoot itself rather than a segment of the axis, so (c) fails.

  The coleorhiza is a protective sheath around the radicle found in many monocot seeds, not a portion of a dicot embryonal axis, so (d) fails.

• practice — not a real PYQ

  Triple fusion in a flowering plant gives rise to

  • (a)The zygote
  • (b)The primary endosperm nucleus
  • (c)The suspensor
  • (d)The pollen tube
  Answerb — The primary endosperm nucleus.

  Triple fusion is the fusion of the second male gamete with the two polar nuclei of the central cell, producing a triploid primary endosperm nucleus that goes on to form the endosperm.

  The zygote comes from syngamy, the fusion of the first male gamete with the egg, so (a) fails. The suspensor arises later, from divisions of the zygote during embryo development, so (c) fails. The pollen tube grows out of a germinating pollen grain and carries the gametes to the embryo sac, so (d) fails.

• practice — not a real PYQ

  Which one of the following is the female gametophyte of an angiosperm?

  • (a)Nucellus
  • (b)Embryo sac
  • (c)Integument
  • (d)Ovary
  Answerb — Embryo sac.

  The embryo sac is the haploid female gametophyte, developing inside the ovule from the functional megaspore and containing the egg cell.

  The nucellus is sporophytic nutritive tissue of the ovule and the integuments are its sporophytic protective coverings, so (a) and (c) fail. The ovary is the basal part of the pistil that encloses the ovules and is likewise sporophytic, so (d) fails.

• practice — not a real PYQ

  In a germinating seed, the part of the embryo that develops into the shoot system is the

  • (a)Radicle
  • (b)Plumule
  • (c)Coleorhiza
  • (d)Micropyle
  Answerb — Plumule.

  The plumule is the embryonic shoot and grows into the stem and leaves.

  The radicle is the embryonic root and grows downward into the root system, so (a) fails. The coleorhiza is a sheath enclosing the radicle in many monocot seeds, so (c) fails. The micropyle is the small pore in the seed coat through which water is taken up as germination begins, so (d) fails.