Algae NCERT Plant Kingdom
Classification, Examples, Characteristics & NEET Biology Notes
📚 Quick Summary
Algae are primarily aquatic, photosynthetic organisms included in the Plant Kingdom in the traditional NCERT classification. Their plant body is generally a simple thallus and they lack true roots, stems and leaves.
The three important classes of algae discussed in NCERT are Chlorophyceae (green algae), Phaeophyceae (brown algae) and Rhodophyceae (red algae).
For NEET Biology, focus especially on pigments, reserve food, habitat, reproduction and important examples of each class.
Algae in NCERT Plant Kingdom
In the NCERT Plant Kingdom chapter, algae are described as chlorophyll-bearing, simple, thalloid organisms that are commonly found in aquatic environments.
Algae may be unicellular, colonial or filamentous. Their body is not differentiated into true roots, stems and leaves.
Many algae are important producers in aquatic ecosystems and contribute significantly to oxygen production.
🎯 Preparing for NEET Biology?
For NEET preparation, read the NCERT descriptions of the three algal classes carefully. Questions are commonly based on the combination of class + pigment + reserve food + example.
Explore NEET Biology Resources →1. General Characteristics of Algae
- Algae are primarily aquatic organisms.
- They contain photosynthetic pigments.
- The plant body is generally a simple thallus.
- They do not possess true roots, stems or leaves.
- They may be unicellular, colonial or multicellular.
- Some algae occur in freshwater while many are marine.
- Reproduction may be vegetative, asexual or sexual.
- Algae form an important component of aquatic food chains.
Algae = Simple thalloid + photosynthetic + mostly aquatic
2. Classification of Algae in NCERT
NCERT discusses three major classes of algae:
- Chlorophyceae – Green algae
- Phaeophyceae – Brown algae
- Rhodophyceae – Red algae
| Class | Major Pigments | Reserve Food | Examples |
|---|---|---|---|
| Chlorophyceae | Chlorophyll a and b | Starch | Chlamydomonas, Volvox, Ulothrix, Spirogyra, Chara |
| Phaeophyceae | Chlorophyll a, c and fucoxanthin | Laminarin and mannitol | Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus |
| Rhodophyceae | Chlorophyll a and d, phycoerythrin | Floridean starch | Polysiphonia, Porphyra, Gelidium, Gracilaria |
3. Chlorophyceae – Green Algae
Chlorophyceae are commonly called green algae because their chlorophyll pigments give them a predominantly green appearance.
Pigments
The major photosynthetic pigments are chlorophyll a and chlorophyll b.
Reserve Food
The reserve food is mainly stored as starch.
Habitat
Green algae are commonly found in freshwater, although some species are marine.
Examples
Important NCERT examples include:
- Chlamydomonas
- Volvox
- Ulothrix
- Spirogyra
- Chara
Green algae → Chlorophyll a + b → Starch
4. Phaeophyceae – Brown Algae
Phaeophyceae are commonly known as brown algae. Their brown colour is mainly associated with the pigment fucoxanthin.
Pigments
The important pigments include chlorophyll a, chlorophyll c and the carotenoid fucoxanthin.
Reserve Food
The reserve food is stored mainly as laminarin and mannitol.
Habitat
Brown algae are predominantly marine and are commonly found in coastal waters.
Examples
- Ectocarpus
- Dictyota
- Laminaria
- Sargassum
- Fucus
Brown algae → Fucoxanthin → Laminarin + Mannitol
5. Rhodophyceae – Red Algae
Rhodophyceae are commonly called red algae. Their characteristic red colour is mainly due to the presence of phycoerythrin.
Pigments
The major pigments include chlorophyll a, chlorophyll d and the phycobilin pigment phycoerythrin.
Reserve Food
The reserve food is stored as floridean starch.
Habitat
Most red algae are marine. Some can occur at considerable depths because their pigments allow them to absorb available wavelengths of light.
Examples
- Polysiphonia
- Porphyra
- Gelidium
- Gracilaria
Red algae → Phycoerythrin → Floridean starch
6. Reproduction in Algae
Algae reproduce by vegetative, asexual and sexual methods.
A. Vegetative Reproduction
Vegetative reproduction commonly occurs by fragmentation. Each fragment can grow into a new individual under suitable conditions.
B. Asexual Reproduction
Asexual reproduction commonly occurs through the formation of zoospores. These spores are generally motile and can develop into new individuals.
C. Sexual Reproduction
Sexual reproduction occurs through the fusion of gametes. Depending on the species, the gametes may be similar or different in size and structure.
The three important forms of sexual reproduction are:
- Isogamy – fusion of similar gametes
- Anisogamy – fusion of dissimilar gametes
- Oogamy – fusion of a large non-motile female gamete with a small motile male gamete
7. Important NCERT Algae Examples
| Alga | Class | NEET Association |
|---|---|---|
| Chlamydomonas | Chlorophyceae | Green alga |
| Volvox | Chlorophyceae | Colonial green alga |
| Spirogyra | Chlorophyceae | Filamentous green alga |
| Sargassum | Phaeophyceae | Brown alga |
| Laminaria | Phaeophyceae | Brown alga |
| Polysiphonia | Rhodophyceae | Red alga |
| Gelidium | Rhodophyceae | Red alga |
8. Economic Importance of Algae
Algae have important ecological and economic roles.
- They act as important primary producers in aquatic ecosystems.
- Several algae are used as food.
- Some algae are used as sources of industrial products.
- Agar is obtained from certain red algae such as Gelidium and Gracilaria.
- Some seaweeds are used as sources of useful substances and phycocolloids.
- Algae contribute significantly to oxygen production in aquatic ecosystems.
9. NEET Biology MCQs on Algae
1. Which of the following is a characteristic feature of algae?
A. Presence of true roots
B. Presence of true stems
C. Simple thalloid body
D. Absence of photosynthetic pigments
✅ Answer: C. Simple thalloid body
2. The reserve food in Chlorophyceae is mainly:
A. Glycogen
B. Starch
C. Laminarin
D. Floridean starch
✅ Answer: B. Starch
3. Fucoxanthin is characteristic of:
A. Chlorophyceae
B. Phaeophyceae
C. Rhodophyceae
D. Bryophytes
✅ Answer: B. Phaeophyceae
4. The reserve food of brown algae is mainly:
A. Starch and glycogen
B. Laminarin and mannitol
C. Floridean starch
D. Cellulose
✅ Answer: B. Laminarin and mannitol
5. Which pigment is mainly responsible for the red colour of red algae?
A. Chlorophyll b
B. Fucoxanthin
C. Phycoerythrin
D. Carotene
✅ Answer: C. Phycoerythrin
6. Floridean starch is the reserve food of:
A. Green algae
B. Brown algae
C. Red algae
D. Mosses
✅ Answer: C. Red algae
7. Which of the following belongs to Phaeophyceae?
A. Spirogyra
B. Chlamydomonas
C. Sargassum
D. Polysiphonia
✅ Answer: C. Sargassum
8. Which of the following is a red alga?
A. Volvox
B. Laminaria
C. Polysiphonia
D. Ulothrix
✅ Answer: C. Polysiphonia
📌 Algae: One-Minute NEET Revision
Chlorophyceae → Green → Chlorophyll a & b →
Starch → Chlamydomonas, Volvox, Spirogyra
Phaeophyceae → Brown → Fucoxanthin →
Laminarin + Mannitol → Sargassum, Laminaria
Rhodophyceae → Red → Phycoerythrin →
Floridean starch → Polysiphonia, Porphyra, Gelidium
🧠Super NEET Memory Trick
Green → Starch
Brown → Laminarin + Mannitol
Red → Floridean starch
Green = Chlorophyll | Brown = Fucoxanthin | Red = Phycoerythrin
🌿 NEET Biology for Odisha Students
Students preparing for NEET in Odisha can use these NCERT-based algae notes for quick revision of the Plant Kingdom chapter. Focus on NCERT terminology, examples, classification and comparison between the three major classes of algae.
Students from Cuttack, Bhubaneswar, Puri, Sambalpur and other parts of Odisha can use this resource alongside their NCERT textbook and regular MCQ practice.
Explore NEET Biology for Odisha Students →📖 Related NCERT Biology Resources
🎯 Final NEET Takeaway
For questions on algae NCERT Plant Kingdom, remember the three-class comparison instead of memorising isolated facts.
Class → Colour → Pigment → Reserve Food → Examples
Read NCERT first, revise the comparison table, and then practise NEET-level MCQs.
NCERT-focused Biology notes, diagrams, MCQs and smart revision resources for Class 11, Class 12 and NEET Biology students.