Biology · Plant Kingdom · NEET
In MOST algae, the dominant, free-living body is the gametophyte (haploid, n). Example: Spirogyra and Chlamydomonas are haplontic — the main plant body is haploid, and the only diploid cell is the zygote. But be careful: this is not true for ALL algae. Some brown algae like Ectocarpus are haplo-diplontic (both phases present), and Fucus is diplontic (sporophyte dominant). So the safe NEET rule is: 'most algae = gametophyte dominant.'
In bryophytes (mosses and liverworts), the GAMETOPHYTE is dominant. The green, leafy or thalloid plant you see IS the haploid gametophyte. The sporophyte is smaller, attached to the gametophyte, and partly DEPENDENT on it for food and water. This is why bryophytes are called the 'amphibians of the plant kingdom' — the dominant haploid body still needs water for reproduction.
In pteridophytes (ferns), the SPOROPHYTE is dominant. The fern plant with roots, stem and leaves that you see is the diploid (2n) sporophyte. The gametophyte is a small, separate, heart-shaped structure called the PROTHALLUS. Both are free-living and independent, but the sporophyte is the large, main, long-living body. This is the first plant group where the sporophyte clearly wins.
Yes. In gymnosperms and angiosperms (seed plants), the SPOROPHYTE is strongly dominant. The tree, shrub or herb you see is the diploid sporophyte. The gametophytes are extremely REDUCED — just a few cells (like the pollen grain = male gametophyte, and the embryo sac / few cells inside the ovule = female gametophyte) and they stay inside and dependent on the sporophyte. They never live on their own.
Go from lower to higher plants and the dominant phase SHIFTS from gametophyte to sporophyte. Algae (most) = gametophyte. Bryophytes = gametophyte. Pteridophytes = sporophyte. Gymnosperms = sporophyte. Angiosperms = sporophyte. And the gametophyte keeps getting SMALLER and more dependent as you move up. NEET loves this exact trend.
The diploid (2n) sporophyte carries two sets of genes, so it can survive harsh land conditions better and hide harmful recessive genes. As plants moved onto dry land, having a tough, long-living diploid body and a tiny protected gametophyte was an advantage. So evolution favoured the sporophyte becoming the main body in vascular and seed plants.
Which of the following statements is true?
Match the plant with the kind of life cycle it exhibits: (a) Spirogyra (b) Fern (c) Funaria (d) Cycas — with (i) Dominant diploid sporophyte, highly reduced gametophyte (ii) Dominant haploid free-living gametophyte (iii) Dominant diploid sporophyte alternating with reduced gametophyte called prothallus (iv) Dominant haploid leafy gametophyte alternating with partially dependent sporophyte
Life cycle of Ectocarpus and Fucus respectively are
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Pteridophytes (ferns) are the first group where the sporophyte is clearly dominant. In algae and bryophytes the gametophyte is dominant; from pteridophytes onward (pteridophytes, gymnosperms, angiosperms) the sporophyte is the main body.
No. MOST algae are haplontic (gametophyte dominant), but there are exceptions. Ectocarpus is haplo-diplontic and Fucus is diplontic (sporophyte dominant). For NEET, remember the general rule but also memorise these two exceptions because they are directly asked.
No. In gymnosperms and angiosperms the gametophyte is highly reduced (only a few cells), never free-living, and stays inside and dependent on the sporophyte. The pollen grain is the male gametophyte and the embryo sac is the female gametophyte.
As you move from algae to angiosperms, dominance shifts from gametophyte to sporophyte, and the gametophyte gets smaller and more dependent. Lower plants = gametophyte world; higher plants = sporophyte world.
