Plant Kingdom
NCERT Line-by-Line Breakdown for NEET 2026
Unit 1: Diversity in Living WorldPlants are not just about green leaves! This chapter takes us on a journey from simple algae to complex flowering plants. We will explore Algae, Bryophytes, Pteridophytes, Gymnosperms, and Angiosperms, along with their unique Life Cycles.
1. Classification Systems
Based on superficial morphological characters (habit, color, number/shape of leaves).
Example: Linnaeus (based on Androecium structure).
Based on natural affinities, including internal features (ultrastructure, anatomy, embryology, phytochemistry).
Example: George Bentham & Joseph Dalton Hooker.
Based on evolutionary relationships between various organisms.
Example: Hutchinson.
💡 Modern Taxonomy Tools:
• Numerical Taxonomy: Uses computers; numbers & codes assigned to all characters.
• Cytotaxonomy: Based on cytological information (Chromosome number, structure, behavior).
• Chemotaxonomy: Uses chemical constituents of the plant.
2. Algae
Chlorophyll-bearing, simple, thalloid, autotrophic, and largely aquatic organisms.
| Class | Common Name | Major Pigments | Stored Food | Cell Wall |
|---|---|---|---|---|
| Chlorophyceae | Green Algae | Chl a, b | Starch | Cellulose |
| Phaeophyceae | Brown Algae | Chl a, c, Fucoxanthin | Mannitol, Laminarin | Cellulose + Algin |
| Rhodophyceae | Red Algae | Chl a, d, Phycoerythrin | Floridean Starch | Cellulose + polysulphate esters |
- Green: Volvox, Ulothrix, Spirogyra, Chara.
- Brown: Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus.
- Red: Polysiphonia, Porphyra, Gracilaria, Gelidium (Agar).
3. Bryophytes (Amphibians of Plant Kingdom)
They live in soil but depend on water for sexual reproduction. The main plant body is haploid (Gametophyte).
🍃 Liverworts
Thalloid body (e.g., Marchantia). Asexual reproduction by fragmentation or Gemmae cups (Green, multicellular, asexual buds).
🌿 Mosses
Two stages: Protonema (creeping, green) & Leafy stage. Vegetative reproduction by fragmentation & budding in secondary protonema.
Example: Funaria, Polytrichum, Sphagnum (Peat moss – used for packing).
4. Pteridophytes (First Vascular Plants)
First terrestrial plants to possess vascular tissues (Xylem & Phloem). The main plant body is Sporophyte (2n).
[Image of pteridophytes life cycle]⚠️ NEET Important Concept: Heterospory
Most pteridophytes are Homosporous (similar spores). However, genera like Selaginella and Salvinia produce two kinds of spores (Heterosporous).
Significance: The development of zygotes into young embryos takes place within the female gametophytes. This event is a precursor to the seed habit.
Classes: Psilopsida (Psilotum), Lycopsida (Selaginella), Sphenopsida (Equisetum), Pteropsida (Dryopteris, Pteris).
5. Gymnosperms (Naked Seeds)
Ovules are not enclosed by any ovary wall and remain exposed.
[Image of gymnosperm life cycle]- 🌲 Mycorrhiza: Fungal association with roots (e.g., Pinus).
- 🌲 Coralloid Roots: Association with N2-fixing Cyanobacteria (e.g., Cycas).
- 🌲 Adaptations: Needle-like leaves, thick cuticle, and sunken stomata to reduce water loss (Xerophytic).
6. Alternation of Generations
[Image of alternation of generation in plants]| Cycle Type | Dominant Phase | Examples (NEET Favorites) |
|---|---|---|
| Haplontic | Gametophyte (n) | Volvox, Spirogyra, Chlamydomonas. |
| Diplontic | Sporophyte (2n) | Gymnosperms, Angiosperms, Fucus. |
| Haplo-diplontic | Intermediate | Bryophytes, Pteridophytes, Ectocarpus, Polysiphonia, Kelps. |
📝 Rapid Fire MCQs
Q1. Agar-agar is obtained from:
- A) Green Algae
- B) Brown Algae
- C) Red Algae
- D) Blue-green Algae
Click to check Answer
Answer: C) Red Algae (Gelidium and Gracilaria).
Q2. Which of the following is responsible for peat formation?
- A) Marchantia
- B) Riccia
- C) Funaria
- D) Sphagnum
Click to check Answer
Answer: D) Sphagnum.