NEET Biology - Unit 1- Salient features and classification of plants- Study Notes - New Syllabus
NEET Biology – Unit 1- Salient features and classification of plants- Study Notes – New Syllabus
Key Concepts:
- Salient features and classification of plants into major groups-Algae, Bryophytes, Pteridophytes, Gymnosperms (three to five salient and distinguishing features and at least two examples of each category);
Salient Features and Classification of Plants
Plants are multicellular, eukaryotic, autotrophic organisms classified based on presence of vascular tissue, type of reproduction, and structural complexity.
🌱 1) Algae
Salient Features:
- Mostly aquatic, some in moist soil or wood
- Simple thallus, can be unicellular, colonial, or filamentous
- Photosynthetic with pigments like chlorophyll a, b, carotenoids
- Reproduce vegetatively (fragmentation), asexually (zoospores), sexually (isogamous, anisogamous, oogamous)
- Can produce hydrocolloids (algin, carrageenan)
Examples: Chlamydomonas, Spirogyra, Volvox, Ulva
Distinguishing Feature: No true roots, stems, or leaves; primary producers in aquatic ecosystems.
🌿 2) Bryophytes
Salient Features:
- Non-vascular, small plants
- Plant body: thallus-like, no true roots, stems, or leaves; possess rhizoids
- Gametophyte stage dominant; sporophyte depends on gametophyte
- Require water for fertilization (amphibians of plant kingdom)
- Reproduce sexually (archegonia & antheridia) and asexually (fragmentation, gemmae)
Examples: Marchantia (liverwort), Funaria, Sphagnum (mosses)
Distinguishing Feature: Hair-like rhizoids, multicellular sex organs, haploid gametophyte dominant.
🌱 3) Pteridophytes
Salient Features:
- Vascular plants with xylem and phloem
- True roots, stems, and leaves; leaves may be microphylls or megaphylls
- Reproduce via spores; no seeds or flowers
- Life cycle exhibits alternation of generations (haploid gametophyte & diploid sporophyte)
- Water required for fertilization; spores can be homosporous or heterosporous
Examples: Pteris (fern), Equisetum (horsetail), Selaginella
Distinguishing Feature: Seedless vascular plants with sporophylls; can grow taller than bryophytes.
🌲 4) Gymnosperms
Salient Features:
- Vascular, woody, seed-producing plants
- Seeds are naked (not enclosed in fruit)
- Needle-like leaves with thick cuticle and sunken stomata (adapted to dry habitats)
- Male & female gametophytes are dependent inside sporangia; fertilization via pollen tube
- Heterosporous: microspores → pollen; megaspores → ovules → seeds
Examples: Pinus, Cycas, Ginkgo, Cedrus
Distinguishing Feature: Seeds exposed on cones, pollen tube delivers male gametes to female gametophyte.
📌 Quick Summary Table
| Plant Group | Salient Features | Examples | Distinguishing Feature |
|---|---|---|---|
| Algae | Aquatic, simple thallus, photosynthetic, fragmentation/zoospores/gametes, hydrocolloids | Chlamydomonas, Volvox | No true roots, stems, or leaves |
| Bryophytes | Non-vascular, rhizoids, gametophyte dominant, water needed for fertilization, sex organs present | Marchantia, Funaria | Haploid gametophyte dominant, multicellular sex organs |
| Pteridophytes | Vascular, true roots/stems/leaves, spores, alternation of generation, water for fertilization | Pteris, Equisetum | Seedless vascular plants with sporophylls |
| Gymnosperms | Vascular, seeds naked, needle leaves, pollen tube fertilization, heterosporous | Pinus, Cycas | Seeds exposed on cones, male/female gametophytes dependent |
✅ Summary
Plants are classified based on structure, vascular system, and reproduction.
Algae → Bryophytes → Pteridophytes → Gymnosperms show increasing complexity.
Gymnosperms are the first seed-producing plants, adapted to terrestrial habitats.