Revision: Diversity in the Living World >> Biological Classification Biology Science (English Medium) Class 11 CBSE

Bacteriophages are virus that infect bacterial cells, e.g. T4 bacteriophage.

Viral particles which contain only protein. They do not contain nucleic acid.

1. Meaning - All single-celled eukaryotes act as a link between plants, animals and fungi; mostly aquatic; have a nucleus and membrane-bound organelles.

2. Chrysophytes - Includes diatoms and golden algae; cell wall has silica; deposits form Diatomaceous Earth (used in polishing and filtration); chief producers in oceans.

3. Dinoflagellates - Mostly marine, photosynthetic; cell wall of cellulosic plates; have two flagella (one longitudinal, one transverse); rapid multiplication of red dinoflagellates (e.g. Gonyaulax) causes red tides.

4. Euglenoids - Have a pellicle instead of a cell wall; photosynthetic in sunlight but become heterotrophs in its absence. e.g. Euglena.

5. Slime Moulds - Saprophytic; feed on decaying matter; undergo syngamy to form a plasmodium that spreads over several feet.

6. Protozoans - 4 types:

• Amoeboid - move by pseudopodia. e.g. Amoeba, Entamoeba
• Flagellated - have flagella; cause sleeping sickness. e.g. Trypanosoma
• Ciliated - have cilia; have a gullet for feeding. e.g. Paramecium
• Sporozoans - no locomotory organelle; all parasitic. e.g. Plasmodium

1. Meaning - All single-celled eukaryotes act as a link between plants, animals and fungi; mostly aquatic; have a nucleus and membrane-bound organelles.

2. Chrysophytes - Includes diatoms and golden algae; cell wall has silica; deposits form Diatomaceous Earth (used in polishing and filtration); chief producers in oceans.

3. Dinoflagellates - Mostly marine, photosynthetic; cell wall of cellulosic plates; have two flagella (one longitudinal, one transverse); rapid multiplication of red dinoflagellates (e.g. Gonyaulax) causes red tides.

4. Euglenoids - Have a pellicle instead of a cell wall; photosynthetic in sunlight but become heterotrophs in its absence. e.g. Euglena.

5. Slime Moulds - Saprophytic; feed on decaying matter; undergo syngamy to form a plasmodium that spreads over several feet.

6. Protozoans - 4 types:

• Amoeboid - move by pseudopodia. e.g. Amoeba, Entamoeba
• Flagellated - have flagella; cause sleeping sickness. e.g. Trypanosoma
• Ciliated - have cilia; have a gullet for feeding. e.g. Paramecium
• Sporozoans - no locomotory organelle; all parasitic. e.g. Plasmodium

1. Meaning - Heterotrophic organisms; body made of thread-like hyphae; network of hyphae = mycelium; cell wall made of chitin; grow in warm and humid places; except yeasts, all are multicellular.

2. Nutrition - Can be saprophytic (feed on dead matter), parasitic or symbiotic (as lichens and mycorrhiza).

3. Reproduction - Asexual by spores (conidia, zoospores, aplanospores); sexual reproduction involves 3 steps - plasmogamy → karyogamy → meiosis; Ascomycetes and Basidiomycetes undergo a dikaryotic stage.

4. 4 Classes of Fungi:

• Phycomycetes - Mycelium aseptate, coenocytic; spores endogenous in sporangium. e.g. Rhizopus, Albugo
• Ascomycetes (Sac fungi) - Asexual spores = conidia; sexual spores = ascospores in ascus. e.g. Aspergillus, Neurospora
• Basidiomycetes - No asexual spores; sexual spores = basidiospores (exogenous). e.g. Agaricus, Ustilago, Puccinia
• Deuteromycetes (Imperfect Fungi) - Sexual form unknown; saprophytic/parasitic. e.g. Alternaria, Colletotrichum

5. Classification basis - Based on morphology, mode of spore formation and fruiting bodies.

6. Important examples - Puccinia (wheat rust), Penicillium (antibiotic), Agaricus (mushroom), Neurospora (genetic research).

1. Meaning- All eukaryotic, chlorophyll-containing organisms; cell wall made of cellulose; mostly autotrophic; some are insectivorous (e.g. Venus fly trap, Bladderwort) or parasitic (e.g. Cuscuta).

2. Members - Includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms.

3. Alternation of generations - Life cycle has two phases - diploid sporophyte and haploid gametophyte - which alternate with each other.

4. Plant groups at a glance:

• Algae - Simple, aquatic, no true roots/stems/leaves. e.g. Seaweed, Green algae
• Bryophytes - Non-vascular, moist environments. e.g. Mosses, Liverworts
• Pteridophytes - Vascular, no seeds, reproduce by spores. e.g. Ferns
• Gymnosperms - Naked seeds in cones, no flowers/fruits. e.g. Pine, Fir
• Angiosperms - Seeds enclosed in fruits, the most diverse group. e.g. Rose, Lily

5. Key features - Have prominent chloroplasts for photosynthesis; membrane-bound organelles; the most diverse group among all kingdoms.

1. Meaning- All eukaryotic, chlorophyll-containing organisms; cell wall made of cellulose; mostly autotrophic; some are insectivorous (e.g. Venus fly trap, Bladderwort) or parasitic (e.g. Cuscuta).

2. Members - Includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms.

3. Alternation of generations - Life cycle has two phases - diploid sporophyte and haploid gametophyte - which alternate with each other.

4. Plant groups at a glance:

• Algae - Simple, aquatic, no true roots/stems/leaves. e.g. Seaweed, Green algae
• Bryophytes - Non-vascular, moist environments. e.g. Mosses, Liverworts
• Pteridophytes - Vascular, no seeds, reproduce by spores. e.g. Ferns
• Gymnosperms - Naked seeds in cones, no flowers/fruits. e.g. Pine, Fir
• Angiosperms - Seeds enclosed in fruits, the most diverse group. e.g. Rose, Lily

5. Key features - Have prominent chloroplasts for photosynthesis; membrane-bound organelles; the most diverse group among all kingdoms.

• Meaning - Heterotrophic, multicellular eukaryotes; cells lack a cell wall; cannot produce their own food.
• Nutrition - Mode of nutrition is holozoic (food obtained by ingestion); food is digested in an internal cavity; food is stored as glycogen or fat.
• Reproduction - By sexual reproduction - copulation of male and female followed by embryological development.
• Other features - Follow a definite growth pattern; higher forms have elaborate sensory and neuromotor mechanisms (nervous system and sensory organs); most are capable of locomotion.
• Cell structure - Has a nucleus and membrane-bound organelles; no chloroplasts (hence cannot photosynthesise); no cell wall (unlike plants and fungi).