🌿 Kingdom Plantae: Complete Algae One Shot (NCERT Line-to-Line) for NEET 2026

Namaskar Bachhon! Welcome to today’s lecture blog. We are going to cover Kingdom Plantae, starting with the Systems of Classification and covering Algae in complete detail. This is strictly based on NCERT and focused on NEET.

Let’s start with the basics! (चलिए शुरू करते हैं क्लासिफिकेशन के आधार से।)

Students who prefer video explanation can watch the lecture first. NCERT-based notes are given below.

1. Systems of Classification (वर्गीकरण की प्रणालियाँ)

Before diving into plants, we must understand how they are classified.

A. Artificial System of Classification

• Proponent (वैज्ञानिक): Carolus Linnaeus.
• Basis: Mainly based on Superficial Morphological Characters (Vegetative characters) like habit, color, number/shape of leaves.
• Main Basis: They gave importance to Sexual Characteristics, specifically the Androecium structure (Stamen number).
• Drawbacks (कमियां):
  1. Equal Weightage: They gave equal weightage to vegetative and sexual characters. This is not correct because vegetative characters are easily affected by the environment (e.g., Leaf shape changes with water availability).
  2. Separation: Closely related species were separated due to minor morphological differences.

B. Natural System of Classification

• Proponents: George Bentham and Joseph Dalton Hooker.
• Basis: Based on Natural Affinities (Natural similarities/relationships).
• Features Considered: They looked at both External features and Internal features (Ultrastructure, Anatomy, Embryology, and Phytochemistry).

C. Phylogenetic System of Classification

• Proponents: Engler and Prantl.
• Current Status: Currently the most accepted system.
• Basis: Based on Evolutionary Relationships (Ancestry).
• Assumption: Organisms belonging to the same taxa have a Common Ancestor.

D. Modern Taxonomy Branches

1. Numerical Taxonomy: Uses computers to analyze data. Numbers and codes are assigned to all characters. Hundreds of characters can be considered simultaneously.
2. Cytotaxonomy: Based on Cytological Information like Chromosome number, structure, and behavior.
3. Chemotaxonomy: Based on Chemical Constituents of the plant (e.g., crystals, fragrance).

2. Algae: General Characteristics (शैवाल: सामान्य लक्षण)

Now, let’s focus on the first group of Kingdom Plantae: Algae.

• Nature: Chlorophyll-bearing, Simple, Thalloid, and Autotrophic.
• Habitat: Largely Aquatic (Found in both Fresh and Marine water).
• Associations (महत्वपूर्ण):
  • With Fungi: Forms Lichen.
  • With Animals: On Sloth Bear (Provides Camouflage/कैमोफ्लाज).

Size and Form (आकार और रूप)

• Microscopic Unicellular: Chlamydomonas.
• Colonial (कॉलोनी बनाने वाले): Volvox (Forms Football-like colony).
• Filamentous: Ulothrix and Spirogyra.
• Massive Plant Body: Kelps (Brown Algae) can reach up to 100 meters.

3. Reproduction in Algae (प्रजनन)

1. Vegetative: By Fragmentation. Found in filamentous algae. Each fragment develops into a thallus.
2. Asexual: By Spores. Most common is Zoospore.
   • Note: Zoospores are Flagellated and Motile.
3. Sexual: Fusion of two gametes.
   • Isogamous: Gametes are similar.
     • Flagellated: Ulothrix.
     • Non-Flagellated (Non-motile): Spirogyra.
   • Anisogamous: Gametes are dissimilar. Example: Eudorina.
   • Oogamous: Female is Large & Static; Male is Small & Motile. Example: Volvox, Fucus.

4. Economic Importance (आर्थिक महत्व) 💰

This section is very important for NEET.

1. CO2 Fixation: Algae carry out 50% of total CO2 fixation on earth via photosynthesis.
2. Oxygen: They increase dissolved oxygen in the immediate environment.
3. Food: 70 species of marine algae are edible.
   • Trick: LPS (Laminaria, Porphyra, Sargassum).
4. Hydrocolloids (Water holding substances):
   • Algin: Produced by Brown Algae.
   • Carrageen: Produced by Red Algae.
5. Agar: Obtained from Gelidium and Gracilaria (Red Algae). Used in ice-creams, jellies, and culture media.
6. Space Food: Chlorella and Spirulina are unicellular and protein-rich. Used by space travelers.

5. Classification of Algae (शैवाल का वर्गीकरण)

Algae are divided into 3 main classes based on pigment and stored food.

A. Chlorophyceae (Green Algae)

• Pigments: Chlorophyll a and b.
• Storage Body:Pyrenoids located in Chloroplasts.
  • Structure: Protein in the center and Starch sheath outside (Beside starch, they contain protein).
• Chloroplast Shape: Discoid, plate-like, reticulate, cup-shaped, spiral, or ribbon-shaped.
• Cell Wall: Inner Cellulose, Outer Pectose.
• Examples: Chlamydomonas, Volvox, Ulothrix, Spirogyra, Chara.

B. Phaeophyceae (Brown Algae)

• Habitat: Mostly Marine.
• Body Structure: Divided into Holdfast (Root-like), Stipe (Stem-like), and Frond (Leaf-like photosynthetic part).
• Pigments: Chlorophyll a, c and Fucoxanthin.
  • Color: Varies from olive green to brown depending on Fucoxanthin content.
• Stored Food: Mannitol and Laminarin.
• Gametes: Pyriform (Pear-shaped) with 2 unequal lateral flagella.
• Examples: Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus.

C. Rhodophyceae (Red Algae)

• Pigments: Chlorophyll a, d and r-phycoerythrin (Red color).
• Habitat: Can survive in Great Depths of oceans because red algae can absorb blue/violet light that penetrates deep.
• Stored Food: Floridean Starch (Structure similar to Amylopectin and Glycogen).
• Reproduction: Complex post-fertilization development. Gametes are Non-motile (No flagella).
• Examples: Polysiphonia, Porphyra, Gracilaria, Gelidium.

6. The Master Table (Comparative Chart) 📊

This table summarizes the key differences for quick revision:

7. NEET Special: Tricks & Important Facts 💡

• Trick for Edible Algae:LPS
  • L – Laminaria
  • P – Porphyra
  • S – Sargassum
• Motility Fact:
  • Ulothrix = Flagellated (Motile)
  • Spirogyra = Non-Flagellated (Non-motile)
• Red Algae Products: Agar comes from Gelidium and Gracilaria.
• Hydrocolloids: Algin (Brown) vs Carrageen (Red).
• Gamete Shape: Brown algae gametes are Pear-shaped (Pyriform).

Teacher’s Note: Students, remember that the “Systems of Classification” and the “Economic Importance of Algae” are hot topics for NEET. Make sure to memorize the examples in the table thoroughly. Next lecture, we will move to Bryophytes!

Keep Studying! Jai Hind!