Plant Kingdom (NEET Biology Class 11): Algae, Bryophytes, Pteridophytes, Gymnosperms & Angiosperms
Algae — the Three Classes (the key NEET table)
🎯 NEET priority: High-yield. 4–6 questions every year. The algae pigment/reserve-food table and the example genera are asked almost verbatim — learn the table cold and you bank these marks.
The plant kingdom climbs from simple water-bound algae up to the flower-and-fruit angiosperms. NEET tests this ladder hard — especially the algae. Algae are chlorophyll-bearing, simple, thalloid, autotrophic organisms, classified into three classes:
Class | Common name | Pigments | Stored food | Examples |
Chlorophyceae | Green algae | Chlorophyll a, b | Starch | Chlamydomonas, Volvox, Spirogyra, Chara |
Phaeophyceae | Brown algae | Chlorophyll a, c + fucoxanthin | Mannitol, laminarin | Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus |
Rhodophyceae | Red algae | Chlorophyll a, d + phycoerythrin | Floridean starch | Porphyra, Gracilaria, Gelidium |
Reproduction in algae — the three modes, memorised in one line
Vegetative — by fragmentation (all three classes).
Asexual — by flagellated zoospores in green algae; biflagellate, pear-shaped zoospores in brown algae; non-motile spores in red algae (red algae have no flagella at any stage — the reason their table entry says "flagella: absent").
Sexual — shows a clean progression: isogamous (gametes similar in size and motile) → anisogamous (gametes dissimilar in size, both motile) → oogamous (a large, non-motile egg + a small, motile male gamete). All three modes can occur across green and brown algae; red algae are strictly oogamous.
Extra structural detail worth knowing
Green algal cells store food in pyrenoids inside the chloroplast (protein + starch); the cell wall has an inner cellulose + outer pectose layer.
Brown algae have a plant body differentiated into a holdfast (anchor), stipe (stalk) and frond (photosynthetic blade) — coated outside in gelatinous algin. Some brown algal kelps reach 100 metres.
Economic uses: agar (from Gelidium and Gracilaria), algin (brown algae) and carrageen (red algae) are commercial hydrocolloids; algae fix ~half of Earth's COâ‚‚.
Exam trap: match the pigment to the colour — fucoxanthin makes brown algae brown, phycoerythrin (r-phycoerythrin) makes red algae red. Reserve food differs too: starch (green) vs mannitol/laminarin (brown) vs floridean starch (red). A second trap: don't assume all algae reproduce the same way — red algae never produce a motile (flagellated) cell, at any stage of their life cycle, unlike green and brown algae.
Bryophytes — Amphibians of the Plant Kingdom
Bryophytes are called the "amphibians of the plant kingdom" — they live on land but need water for sexual reproduction (the motile male gametes swim to the egg). The plant body is a gametophyte (the dominant, independent, haploid phase) — it lacks true root/stem/leaf, though root-like, stem-like or leaf-like structures may be present, attached to the substrate by uni/multicellular rhizoids.
Liverworts have a thalloid, dorsiventral body — e.g. Marchantia.
Mosses — e.g. Funaria, Polytrichum, Sphagnum — have upright, slender axes with spirally arranged leaves; growth begins with a creeping protonema stage that develops from a germinating spore. Sphagnum provides peat (fuel, and packing material for its water-holding capacity) and, with lichens, is a pioneer coloniser of bare rock.
The bryophyte life cycle — a favourite "sequence" question
The male sex organ, the antheridium, produces biflagellate antherozoids; the flask-shaped female sex organ, the archegonium, produces a single egg. Both are multicellular — a defining bryophyte feature. Antherozoids are released into a film of water and swim to the archegonium; fertilisation gives a diploid zygote that does not immediately undergo meiosis — instead it grows into a multicellular sporophyte, which stays attached to and nutritionally dependent on the gametophyte. Some sporophyte cells then undergo meiosis (reduction division) to produce haploid spores, which germinate into new gametophytes.
Sequence to memorise: gametophyte (n) → antheridium/archegonium → antherozoid + egg → fertilisation → zygote (2n) → sporophyte (2n, dependent) → meiosis → spores (n) → gametophyte (n).
Pteridophytes — the First Vascular Plants
Pteridophytes (horsetails and ferns) are the first true vascular plants — the main plant body is the sporophyte itself, differentiated into true root, stem and leaves with well-developed xylem and phloem. The sporophyte bears sporangia that produce spores by meiosis.
Spores germinate into a small, free-living, photosynthetic gametophyte called the prothallus — it needs cool, damp, shady places to grow.
The prothallus bears antheridia and archegonia. Just like in bryophytes, water is required to carry the male gametes to the archegonium; the resulting zygote grows, while still attached, into the next sporophyte.
Most are homosporous (one kind of spore); Selaginella and Salvinia are heterosporous (produce micro- and megaspores) — a step toward the seed habit, since the megaspore stays retained and nourished, foreshadowing the ovule.
Four classes: Psilopsida (Psilotum), Lycopsida (Selaginella, Lycopodium), Sphenopsida (Equisetum), Pteropsida (ferns — Dryopteris, Pteris).
Exam trap: pteridophytes are sporophyte-dominant — the opposite of bryophytes, which are gametophyte-dominant. Don't confuse the prothallus (pteridophyte gametophyte) with the protonema (moss gametophyte's juvenile stage).
Gymnosperms — Naked Seeds
Gymnosperms (gymnos = naked, sperma = seeds) bear naked seeds — the ovules are not enclosed in an ovary, so the seeds sit exposed on cones. They are heterosporous and include medium-to-tall trees.
Examples: Cycas, Pinus, Cedrus, Ginkgo, Ephedra. (Sequoia, a redwood, is among the tallest trees.)
Special roots: Pinus has mycorrhiza (fungal association); Cycas has coralloid roots with nitrogen-fixing cyanobacteria.
Gymnosperm reproduction — where "naked" actually comes from
Microsporophylls (bearing microsporangia → pollen) and megasporophylls (bearing megasporangia → ovules) are arranged spirally to form male cones and female cones respectively. In the ovule, the megaspore mother cell undergoes meiosis to give 4 megaspores; one develops into a multicellular female gametophyte bearing 2+ archegonia — but unlike bryophytes and pteridophytes, this gametophyte is never free-living: it stays retained inside the megasporangium on the sporophyte. Pollen (carried by wind) lands near the ovule's opening; the pollen tube grows toward the archegonia and discharges the male gametes near the egg. After fertilisation, the zygote → embryo and the ovule → seed — but since the ovule was never enclosed in an ovary wall, the resulting seed remains uncovered (naked). That is precisely why gymnosperms are "naked-seeded".
Angiosperms & Alternation of Generations
Angiosperms (flowering plants) bear seeds enclosed in fruits, their pollen grains and ovules developing inside specialised structures — flowers. They are split into dicotyledons (two cotyledons) and monocotyledons (one cotyledon), and dominate today's flora — ranging in size from the world's smallest flowering plant, Wolffia, to Eucalyptus trees over 100 metres tall.
Unique feature: double fertilisation — one male gamete fuses with the egg (forming the zygote), the other with two polar nuclei (forming the triploid endosperm).
Alternation of generations: all plants alternate a diploid sporophyte with a haploid gametophyte. The trend up the kingdom is a shrinking gametophyte and a dominant sporophyte — gametophyte-dominant in bryophytes, sporophyte-dominant from pteridophytes onward.
Ploidy quick-reference — a direct NCERT exercise question
NCERT itself asks students to state the ploidy of specific cells across the plant kingdom — this converts straight into an MCQ:
Structure | Ploidy | Why |
Protonemal cell of a moss | Haploid (n) | Part of the gametophyte generation |
Leaf cell of a moss | Haploid (n) | The whole moss plant body is gametophytic |
Prothallus cell of a fern | Haploid (n) | The fern gametophyte |
Zygote of a fern | Diploid (2n) | Product of fertilisation, start of the new sporophyte |
Gemma cell in Marchantia | Haploid (n) | A vegetative bud budded off the haploid thallus |
Meristem cell of a monocot | Diploid (2n) | Part of the sporophyte (main plant body) |
Ovum of a liverwort | Haploid (n) | A gamete, produced by the gametophyte |
Primary endosperm nucleus (dicot) | Triploid (3n) | Formed by triple fusion (polar nuclei × 2 + male gamete) |
Why this matters for NEET
The algae table is the single most-asked item — pigment ↔ colour ↔ reserve food ↔ example genus.
Tag-line recall: bryophytes = "amphibians of plant kingdom"; pteridophytes = first vascular plants, sporophyte-dominant; gymnosperms = naked seeds, gametophyte never free-living; angiosperms = double fertilisation.
Trap: Selaginella & Salvinia are heterosporous (most pteridophytes are homosporous); Cycas has coralloid roots, Pinus has mycorrhiza; ploidy questions trip students who forget that the entire moss/liverwort plant body (not just the gametes) is haploid.
Test Yourself: MCQs, PYQs & Active Recall
Answer these, then close the article and do an Active Recall. Reveal each answer only after you commit to one.
Practice Questions
Q1. The reserve food material in brown algae (Phaeophyceae) is:
(a) Glycogen
(b) Floridean starch
(c) Starch
(d) Mannitol and laminarin
Show answer
Answer: (d) — Brown algae store food as mannitol and laminarin (complex carbohydrates); green algae store starch, red algae floridean starch.
Q2. The pigment responsible for the red colour of Rhodophyceae is:
(a) Carotene
(b) Phycoerythrin
(c) Fucoxanthin
(d) Chlorophyll b
Show answer
Answer: (b) — Phycoerythrin (r-phycoerythrin) gives red algae their colour; fucoxanthin makes brown algae brown.
Q3. Agar, used in microbiology, is obtained from:
(a) Green algae
(b) Brown algae
(c) Red algae (Gelidium, Gracilaria)
(d) Cyanobacteria
Show answer
Answer: (c) — Agar is a hydrocolloid from red algae Gelidium and Gracilaria; algin comes from brown algae.
Q4. Bryophytes are called 'amphibians of the plant kingdom' because:
(a) They have roots and shoots
(b) They need water for sexual reproduction
(c) They are heterosporous
(d) They live only in water
Show answer
Answer: (b) — Though they grow on land, bryophytes require water for the motile male gametes to reach the egg — hence 'amphibians'.
Q5. The dominant photosynthetic phase in a moss is the:
(a) Gametophyte
(b) Sporophyte
(c) Prothallus
(d) Zygote
Show answer
Answer: (a) — In bryophytes the gametophyte is the dominant, independent phase; the sporophyte is dependent on it.
Q6. The first true vascular plants (with xylem and phloem) are the:
(a) Gymnosperms
(b) Pteridophytes
(c) Bryophytes
(d) Algae
Show answer
Answer: (b) — Pteridophytes are the first plants with proper vascular tissue (xylem & phloem).
Q7. The gametophyte of a fern is called the:
(a) Protonema
(b) Strobilus
(c) Prothallus
(d) Thallus
Show answer
Answer: (c) — The free-living, photosynthetic pteridophyte gametophyte is the prothallus (needs cool, damp, shady conditions).
Q8. Which pair of pteridophytes is heterosporous?
(a) Dryopteris and Pteris
(b) Equisetum and Psilotum
(c) Lycopodium and Funaria
(d) Selaginella and Salvinia
Show answer
Answer: (d) — Selaginella and Salvinia produce two kinds of spores (micro- and megaspores) — heterospory, a step toward the seed habit.
Q9. Gymnosperms are characterised by:
(a) Spores instead of seeds
(b) Seeds enclosed in fruits
(c) Absence of vascular tissue
(d) Naked seeds (not enclosed in an ovary)
Show answer
Answer: (d) — Gymnosperms bear naked seeds — ovules and resulting seeds are exposed, not enclosed in an ovary/fruit.
Q10. Coralloid roots with nitrogen-fixing cyanobacteria are found in:
(a) Pinus
(b) Cycas
(c) Ginkgo
(d) Ephedra
Show answer
Answer: (b) — Cycas has coralloid roots harbouring cyanobacteria; Pinus instead has mycorrhizal roots.
Q11. Double fertilisation is a characteristic feature of:
(a) Bryophytes
(b) Pteridophytes
(c) Gymnosperms
(d) Angiosperms
Show answer
Answer: (d) — Only angiosperms show double fertilisation — one male gamete forms the zygote, the other the triploid endosperm.
Q12. Which one is a red alga?
(a) Porphyra
(b) Ectocarpus
(c) Spirogyra
(d) Laminaria
Show answer
Answer: (a) — Porphyra (and Gracilaria, Gelidium) are red algae; Laminaria/Ectocarpus are brown; Spirogyra is green.
Q13. Sexual reproduction with a large non-motile egg and a small motile male gamete is called:
(a) Conjugation
(b) Anisogamy
(c) Oogamy
(d) Isogamy
Show answer
Answer: (c) — Oogamy: a large non-motile egg fuses with a small motile male gamete — seen across algae and in all higher plants.
Q14. Which class of algae never produces a motile (flagellated) cell at any stage?
(a) Chlorophyceae
(b) Phaeophyceae
(c) None — all algae are motile
(d) Rhodophyceae
Show answer
Answer: (d) — Rhodophyceae (red algae) are unique among algae in producing no flagellated cells at any life-cycle stage.
Q15. In a moss, the diploid zygote develops directly into a:
(a) Sporophyte
(b) New gametophyte
(c) Protonema
(d) Prothallus
Show answer
Answer: (a) — The zygote grows into a dependent sporophyte (still attached to the gametophyte); it does NOT undergo immediate meiosis.
Q16. The gymnosperm female gametophyte, unlike that of bryophytes and pteridophytes, is:
(a) Absent
(b) Diploid
(c) Never free-living — retained on the sporophyte
(d) Free-living
Show answer
Answer: (c) — Unlike bryophyte/pteridophyte gametophytes, the gymnosperm female gametophyte stays retained within the megasporangium.
Q17. The world's smallest flowering plant is:
(a) Selaginella
(b) Wolffia
(c) Chara
(d) Marchantia
Show answer
Answer: (b) — Wolffia is the smallest known angiosperm; Eucalyptus, in contrast, can exceed 100 metres in height.
Q18. Ploidy of a fern prothallus cell is:
(a) Triploid (3n)
(b) Diploid (2n)
(c) Tetraploid (4n)
(d) Haploid (n)
Show answer
Answer: (d) — The prothallus is the fern gametophyte — entirely haploid, like the moss plant body.
NEET Previous Year Questions (PYQs)
Real NEET previous-year questions on this chapter, with explanations in our own words.
Q13. Which of the following is a pair of green algae? (NEET PYQ)
(a) Gracilaria and Gelidium
(b) Porphyra and Fucus
(c) Spirogyra and Chara
(d) Laminaria and Sargassum
Show answer
Answer: (c) — Spirogyra and Chara are Chlorophyceae (green algae). The others are red or brown algae.
Q14. The stored food in Chlorophyceae is: (NEET PYQ)
(a) Starch
(b) Floridean starch
(c) Laminarin
(d) Mannitol
Show answer
Answer: (a) — Green algae (Chlorophyceae) store starch, like higher plants; their wall has an inner cellulose layer.
Q15. Pteridophytes differ from bryophytes in having: (NEET PYQ)
(a) Naked seeds
(b) Well-developed vascular tissue
(c) A dominant gametophyte
(d) No need of water for fertilisation
Show answer
Answer: (b) — Pteridophytes are the first vascular plants (xylem & phloem) and are sporophyte-dominant; bryophytes lack true vascular tissue.
Q16. Peat, used as fuel, is obtained from: (NEET PYQ)
(a) Sphagnum
(b) Marchantia
(c) Funaria
(d) Riccia
Show answer
Answer: (a) — Sphagnum (a moss) provides peat; it and lichens are also pioneer colonisers of bare rock.
Q17. In which group are the seeds naked? (NEET PYQ)
(a) Pteridophytes
(b) Bryophytes
(c) Gymnosperms
(d) Angiosperms
Show answer
Answer: (c) — Gymnosperms (gymnos = naked) bear seeds not enclosed in an ovary — they sit exposed on cones.
Q18. The brown colour of Phaeophyceae is due to: (NEET PYQ)
(a) Fucoxanthin
(b) Chlorophyll b
(c) Floridean starch
(d) Phycoerythrin
Show answer
Answer: (a) — Fucoxanthin, a xanthophyll pigment, gives brown algae their colour; they also have chlorophyll a and c.
Q19. The prothallus is the gametophyte of: (NEET PYQ)
(a) Mosses
(b) Gymnosperms
(c) Liverworts
(d) Ferns (pteridophytes)
Show answer
Answer: (d) — The pteridophyte gametophyte is the small, independent prothallus; in mosses the gametophyte develops from a protonema.
Q20. Which of the following is correctly matched? (NEET PYQ)
(a) Pinus — coralloid roots
(b) Ginkgo — mangrove roots
(c) Cycas — mycorrhiza
(d) Cycas — coralloid roots
Show answer
Answer: (d) — Cycas has coralloid roots (with cyanobacteria); Pinus has mycorrhizal roots.
Q21. Alternation of generations in plants is between: (NEET PYQ)
(a) Spore and seed
(b) Diploid sporophyte and haploid gametophyte
(c) Two diploid phases
(d) Two haploid phases
Show answer
Answer: (b) — Plants alternate a diploid spore-producing sporophyte with a haploid gamete-producing gametophyte.
Q22. Agar and algin are obtained respectively from: (NEET PYQ)
(a) Brown and red algae
(b) Red and brown algae
(c) Green and red algae
(d) Red and green algae
Show answer
Answer: (b) — Agar comes from red algae (Gelidium, Gracilaria); algin comes from brown algae.
Active Recall Prompt
Write everything you can recall, naming each group first. Cover: Algae (the three classes with pigments, stored food, reproduction modes, example genera); Bryophytes (amphibians of the plant kingdom, the full life cycle — antheridium/archegonium/zygote/sporophyte/spores); Pteridophytes (first vascular plants, prothallus, hetero/homospory); Gymnosperms (naked seeds, cones, pollen tube); Angiosperms (double fertilisation, size extremes) plus alternation of generations and the ploidy table. Begin each fact with its group and end it with a full stop.