# Plant Kingdom (NEET Biology Class 11): Algae, Bryophytes, Pteridophytes, Gymnosperms & Angiosperms

Source: https://tracknation.in/story/plant-kingdom-neet-biology-class-11-algae-bryophytes-pteridophytes-gymnosperms-angiosperms (TrackNation — free UPSC notes with PYQs)

> NEET Class 11 Plant Kingdom, mined from NCERT: the three algae classes with their pigments, stored food, reproduction modes (isogamy/anisogamy/oogamy) and example genera; bryophytes with the full life cycle (antheridium, archegonium, sporophyte); pteridophytes (first vascular plants, prothallus, heterospory); gymnosperms (naked seeds, cone structure, pollen tube) and angiosperms (double fertilisation, size extremes), plus a ploidy quick-reference table and alternation of generations. With 18 MCQ

## 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 CO₂.

**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

**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

**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

**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

**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

**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

**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

**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

**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)

**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

**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

**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

**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

**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

**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

**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

**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

**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)

**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

**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

**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

**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

**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

**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

**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)

**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

**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

**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

**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.