Q31.In which of the following plants, the gametophyte does not represent an independent free living generation?
(A) Polytrichum
(B) Funaria
(C) Marchantia
(D) Pinus
In Pinus, the gametophyte does not represent an independent free-living generation, as both male (pollen grain) and female (embryo sac within ovule) gametophytes are dependent on the sporophyte parent. Bryophytes like Polytrichum, Funaria, and Marchantia have prominent, independent gametophytes. Option (D) is correct.
Option Analysis
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(A) Polytrichum: Incorrect; moss with independent leafy gametophyte (protonema → gametophore) dominating life cycle.
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(B) Funaria: Incorrect; classic moss where green gametophyte is free-living, photosynthetic, and produces gametes.
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(C) Marchantia: Incorrect; liverwort with independent thalloid gametophyte bearing gametangiophores.
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(D) Pinus: Correct; gymnosperm where reduced gametophytes (pollen tube, prothallial cells) rely on sporophyte for nutrition.
Introduction to Gametophyte Generations
Gametophyte does not represent independent free living generation in seed plants like Pinus, unlike bryophytes where it’s dominant and photosynthetic. This shift marks vascular plant evolution from gametophyte-dominant to sporophyte-dominant cycles.
Bryophyte Gametophytes (A-C)
Polytrichum, Funaria, Marchantia feature independent gametophytes: protonema develops into leafy/thalloid structures producing gametes autonomously.
Pinus Reduced Gametophyte
In Pinus, microgametophyte (pollen) and megagametophyte (ovule nucellus-dependent) are parasitic on diploid sporophyte; no free-living phase.
