How to Use This Page
Solve each Samacheer Kalvi exercise question on your own first, then compare your answer with the solutions below. Plant Kingdom is a classification-heavy chapter — focus on the key differences between plant groups and their life cycles.
Key Concepts (Quick Recap)
Classification of Plant Kingdom
Comparison of Plant Groups
| Feature | Algae | Bryophytes | Pteridophytes | Gymnosperms | Angiosperms |
|---|---|---|---|---|---|
| Plant body | Thallus (no differentiation) | Thallus or leafy | Root, stem, leaves | Root, stem, leaves | Root, stem, leaves, flowers |
| Vascular tissue | Absent | Absent | Present | Present | Present |
| Seeds | Absent | Absent | Absent | Naked seeds | Seeds in fruit |
| Flowers | Absent | Absent | Absent | Absent (cones) | Present |
| Water for fertilisation | Yes | Yes | Yes | No (pollen) | No (pollen) |
| Dominant phase | Gametophyte | Gametophyte | Sporophyte | Sporophyte | Sporophyte |
| Habitat | Aquatic/wet | Moist/terrestrial | Moist/shady | Terrestrial | All habitats |
Algae — Three Classes
| Feature | Chlorophyceae (Green) | Phaeophyceae (Brown) | Rhodophyceae (Red) |
|---|---|---|---|
| Pigments | Chlorophyll a, b | Chlorophyll a, c, fucoxanthin | Chlorophyll a, d, phycoerythrin |
| Stored food | Starch | Laminarin, mannitol | Floridean starch |
| Cell wall | Cellulose | Cellulose + algin | Cellulose + agar |
| Flagella | 2 (equal) | 2 (unequal) | Absent |
| Examples | Spirogyra, Chlamydomonas, Volvox | Fucus, Sargassum, Laminaria | Polysiphonia, Gelidium, Porphyra |
Economic Importance of Algae
- Food: Porphyra (red algae), Sargassum (brown algae)
- Agar-agar: From Gelidium and Gracilaria (red algae) — used in culture media and food
- Carrageenan: From red algae — used in ice cream, jelly
- Algin: From brown algae — used in ice cream, toothpaste
- Iodine: From brown algae (Laminaria, Fucus)
- Diatoms: Form diatomaceous earth — used in filtration, polishing
Bryophytes — Key Points
- Called "amphibians of the plant kingdom" — need water for fertilisation
- Gametophyte is the dominant phase
- No vascular tissue (xylem/phloem)
- Reproduce by spores
- Root-like structures = rhizoids (not true roots)
- Sex organs: Antheridium (male), Archegonium (female)
- Economic importance: Sphagnum (peat moss) used as fuel, packing material
Pteridophytes — Key Points
- First true vascular plants (xylem and phloem)
- First true roots, stems, and leaves
- Sporophyte is the dominant phase
- Reproduce by spores (no seeds)
- Leaves = fronds (megaphylls)
- Examples: Ferns (Pteris, Nephrolepis), Selaginella, Equisetum
- Economic importance: Ornamental ferns, soil binders
Gymnosperms — Key Points
- "Gymno" = naked, "sperma" = seed — naked seeds
- No fruit, no flowers — produce cones (strobili)
- Pollination by wind
- Vascular tissue present (tracheids, no vessels in most)
- Evergreen, woody trees
- Examples: Cycas, Pinus, Ginkgo, Cedrus
Angiosperms — Key Points
- "Angio" = covered, "sperma" = seed — seeds enclosed in fruit
- Produce flowers and fruits
- Most diverse group (~300,000 species)
- Divided into Dicots (two cotyledons) and Monocots (one cotyledon)
| Feature | Dicotyledonae | Monocotyledonae |
|---|---|---|
| Cotyledons | Two | One |
| Venation | Reticulate | Parallel |
| Root system | Taproot | Fibrous root |
| Stem | Branched | Unbranched |
| Flowers | Tetramerous/Pentamerous | Trimerous |
| Vascular bundles | Open, arranged in ring | Closed, scattered |
| Examples | Mango, Pea, Rose | Rice, Wheat, Maize |
Life Cycles
- Haplontic: Dominant haploid phase (algae) — zygote is the only diploid stage
- Diplontic: Dominant diploid phase (gymnosperms, angiosperms) — gametes are the only haploid stage
- Haplodiplontic: Both phases are multicellular (bryophytes, pteridophytes) — alternation of generations
I. Choose the Best Answer (MCQs)
Q1. Bryophytes are called amphibians of the plant kingdom because (a) They live in water only (b) They live on land but need water for fertilisation (c) They can live both on land and in water (d) They have gills like amphibians
Q2. Which of the following is a red alga? (a) Spirogyra (b) Sargassum (c) Polysiphonia (d) Chlamydomonas
Q3. The stored food in brown algae is (a) Starch (b) Laminarin (c) Floridean starch (d) Glycogen
Q4. Gymnosperms are called "naked seed" plants because (a) They have no leaves (b) Their seeds are not enclosed in a fruit (c) They have no vascular tissue (d) They reproduce by spores
Q5. In angiosperms, the megasporangium is called (a) Anther (b) Ovule (c) Stigma (d) Style
II. Fill in the Blanks
1. Bryophytes are called the amphibians of the plant kingdom because they need water for fertilisation. 2. The dominant phase in bryophytes is the gametophyte. 3. The dominant phase in angiosperms is the sporophyte. 4. The stored food in green algae is starch. 5. The stored food in brown algae is laminarin. 6. The stored food in red algae is floridean starch. 7. The male sex organ in bryophytes is called antheridium. 8. The female sex organ in bryophytes is called archegonium. 9. The root-like structures in bryophytes are called rhizoids. 10. Pteridophytes are the first plants to possess vascular tissue (xylem and phloem). 11. Gymnosperms produce naked seeds (not enclosed in fruit). 12. Angiosperms produce seeds enclosed in a fruit. 13. Dicotyledonae have two cotyledons. 14. Monocotyledonae have one cotyledon. 15. Agar-agar is obtained from red algae (Gelidium, Gracilaria).
III. True or False (with corrections for false statements)
IV. Match the Following
| Column A | Column B | Answer |
|---|---|---|
| 1. Chlorophyceae | (a) Laminarin stored food | (b) Starch stored food |
| 2. Phaeophyceae | (b) Starch stored food | (a) Laminarin stored food |
| 3. Rhodophyceae | (c) Floridean starch stored food | (c) Floridean starch stored food |
| 4. Bryophytes | (d) Amphibians of plant kingdom | (d) Amphibians of plant kingdom |
| 5. Pteridophytes | (e) First vascular plants | (e) First vascular plants |
V. Answer Briefly (2-mark questions)
VI. Answer in Detail (5-mark questions)
Common Mistakes to Avoid
- Calling algae plants with roots, stems, and leaves: Algae have a thallus body — no differentiation into true roots, stems, or leaves.
- Saying bryophytes have vascular tissue: Bryophytes do NOT have vascular tissue. Pteridophytes are the first plants with xylem and phloem.
- Confusing stored food in algae: Green algae → starch, Brown algae → laminarin, Red algae → floridean starch. Don't mix them up.
- Calling gymnosperms "seedless": Gymnosperms DO have seeds (naked seeds). Pteridophytes are seedless.
- Confusing the dominant phase: Bryophytes → gametophyte dominant; Pteridophytes, Gymnosperms, Angiosperms → sporophyte dominant.
- Saying bryophytes have roots: Bryophytes have rhizoids, not true roots. Rhizoids only anchor the plant; they don't absorb water like true roots.
- Forgetting double fertilisation in angiosperms: Angiosperms have double fertilisation — one male gamete fuses with the egg cell, and the other fuses with polar nuclei to form endosperm.
Exam Checklist
- [ ] Can you classify plants into algae, bryophytes, pteridophytes, gymnosperms, and angiosperms?
- [ ] Can you describe the three classes of algae with pigments, stored food, and examples?
- [ ] Can you explain why bryophytes are called amphibians of the plant kingdom?
- [ ] Can you compare bryophytes and pteridophytes (at least 5 points)?
- [ ] Can you distinguish between gymnosperms and angiosperms?
- [ ] Can you distinguish between dicots and monocots (at least 8 points)?
- [ ] Can you explain alternation of generations with examples?
- [ ] Can you explain the economic importance of algae, bryophytes, and pteridophytes?
- [ ] Can you describe the life cycles: haplontic, diplontic, and haplodiplontic?
- [ ] Can you give at least 3 examples of each plant group?