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FIVE KINGDOM CLASSIFICATION (Whittaker, 1969):
Kingdom │ Cell type │ Nutrition │ Example
───────────┼────────────┼──────────────┼────────────────
Monera │ Prokaryote │ Autotrophic/ │ Bacteria,
│ │ Heterotrophic│ Cyanobacteria
───────────┼────────────┼──────────────┼────────────────
Protista │ Eukaryote │ Autotrophic/ │ Amoeba,
│ unicellular│ Heterotrophic│ Paramecium, Algae
───────────┼────────────┼──────────────┼────────────────
Fungi │ Eukaryote │ Saprophytic │ Mushroom, Yeast,
│ multicell │ (dead matter)│ Penicillium
───────────┼────────────┼──────────────┼────────────────
Plantae │ Eukaryote │ Autotrophic │ All plants
│ multicell │ (photosyn.) │
───────────┼────────────┼──────────────┼────────────────
Animalia │ Eukaryote │ Heterotrophic│ All animals
│ multicell │ (ingest food)│
PROKARYOTE vs EUKARYOTE:
Prokaryote: No membrane-bound nucleus, no membrane organelles
Small (1-10 μm), circular DNA, 70S ribosomes
Eukaryote: Has nucleus (membrane-bound), membrane organelles
Larger (10-100 μm), linear DNA, 80S ribosomes
PLANT KINGDOM CLASSIFICATION:
THALLOPHYTA (Algae):
No differentiated body parts
Aquatic, contain chlorophyll
Examples: Spirogyra, Chara, Ulva (sea lettuce)
BRYOPHYTA (Mosses, Liverworts):
Amphibians of plant kingdom
No vascular tissue (no xylem/phloem)
Moist habitats
Examples: Funaria (moss), Marchantia
PTERIDOPHYTA (Ferns):
First land plants with vascular tissue
No seeds, reproduce by spores
Examples: Fern (Dryopteris), Horsetail, Club moss
GYMNOSPERMS (Naked seeds):
Seeds not enclosed in fruit
Mostly evergreen trees
Examples: Pine, Cycas, Ginkgo, Sequoia
ANGIOSPERMS (Flowering plants):
Seeds enclosed in fruit (ovary)
Two classes:
Dicots: 2 cotyledons, reticulate venation (Mango, Rose)
Monocots: 1 cotyledon, parallel venation (Grass, Wheat)
ROOT SYSTEM DIAGRAM:
Taproot system: Fibrous root system:
│ (main taproot) ║ ║ ║ ║ ║ (many equal roots)
/│\ ║ ║ ║ ║ ║
/ │ \ (lateral roots) ║ ║ ║ ║ ║
/ │ \
Examples: Dicots Examples: Monocots
(mango, carrot, bean) (grass, wheat, rice)
ROOT MODIFICATIONS:
Storage: Carrot, Radish, Turnip (store food)
Support: Banyan (prop/aerial roots hang down)
Climbing: Ivy (clinging roots)
Breathing: Mangrove (pneumatophores come up for air)
STEM MODIFICATIONS:
Underground: Potato (tuber), Ginger (rhizome), Onion (bulb)
Aerial: Cactus (photosynthesis), Tendrils (climbing)
LEAF PARTS DIAGRAM:
┌───────────────────────────────────┐
│ Leaf blade │
│ (lamina) │
│ ───────────────── │
│ / Midrib \ │
│ / (main vein) \ │
│ ├─ Leaf veins │
│ │ │
│ │ Petiole (leaf stalk) │
│ │ │
└──┴──── Node (where leaf joins stem)
ANIMAL CELL:
┌────────────────────────────────────────┐
│ Cell membrane │
│ ┌──────────────┐ │
│ │ │ Nucleus │
│ │ ◯ Nucleolus│ │
│ │ │ │
│ └──────────────┘ │
│ │
│ ⊕ Mitochondria (powerhouse) │
│ [:::] Rough ER (ribosomes on it) │
│ [ ] Smooth ER (lipid synthesis) │
│ [Golgi] Golgi apparatus │
│ [L] Lysosome (digestion) │
│ [Ce] Centriole (cell division) │
│ ··· Ribosomes (protein synthesis) │
└────────────────────────────────────────┘
PLANT CELL ADDITIONAL FEATURES:
+ Cell wall (cellulose) — outside membrane
+ Chloroplast — for photosynthesis
+ Large central vacuole — 90% of plant cell volume
− No Centriole in plant cells
MITOSIS (Somatic cell division):
INTERPHASE (not a phase of mitosis, but preparation):
G1: Cell grows in size
S: DNA replication (2N→4N in terms of DNA)
G2: Preparation for division
PHASES OF MITOSIS:
PROPHASE:
● Chromatin condenses into visible chromosomes
● Nuclear envelope dissolves
● Spindle fibres form
METAPHASE:
● Chromosomes align at equatorial plate (middle)
● Centromeres attached to spindle fibres
ANAPHASE:
● Centromeres split
● Sister chromatids move to opposite poles
● Cell elongates
TELOPHASE:
● Chromosomes reach poles, decondense
● Nuclear envelope reforms
● Two nuclei formed
CYTOKINESIS:
● Cytoplasm divides
● Two daughter cells formed (genetically identical!)
RESULT: 1 diploid cell (2n) → 2 diploid cells (2n)
MEIOSIS I (Reduction division):
PROPHASE I (longest, most complex):
Leptotene → Zygotene → Pachytene → Diplotene → Diakinesis
KEY EVENT: Crossing over in Pachytene (exchange of DNA between homologous chromosomes)
Creates genetic recombination!
METAPHASE I: Bivalents align at plate
ANAPHASE I: Homologous chromosomes separate (NOT sister chromatids)
TELOPHASE I: 2 haploid cells
MEIOSIS II (Like mitosis):
Sister chromatids separate
4 haploid daughter cells formed
RESULT: 1 diploid (2n) → 4 haploid cells (n)
These become gametes (sperm, egg)
PHOTOSYNTHESIS occurs in CHLOROPLAST:
┌───────────────────────────────────────┐
│ CHLOROPLAST │
│ │
│ LIGHT REACTIONS (Thylakoid membrane)│
│ Light → ATP + NADPH + O₂ │
│ H₂O is split (photolysis) │
│ O₂ is released! │
│ │
│ DARK REACTIONS/CALVIN CYCLE (Stroma)│
│ CO₂ + ATP + NADPH → Glucose │
│ (C3 cycle, doesn't need direct │
│ light but needs ATP/NADPH) │
└───────────────────────────────────────┘
OVERALL EQUATION:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
[light, chlorophyll]
FACTORS AFFECTING PHOTOSYNTHESIS:
Light intensity ↑ → Rate ↑ (up to saturation point)
CO₂ concentration ↑ → Rate ↑
Temperature: optimal 25-35°C
Water: deficiency → stomata close → less CO₂ → less photosynthesis
AEROBIC RESPIRATION:
GLYCOLYSIS (Cytoplasm, without O₂):
Glucose (6C) → 2 Pyruvate (3C) + 2 ATP + 2 NADH
KREBS CYCLE/TCA (Mitochondria matrix):
2 Pyruvate → Acetyl CoA → CO₂ released + 2 ATP + NADH, FADH₂
ELECTRON TRANSPORT CHAIN (Inner mitochondria membrane):
NADH, FADH₂ → ATP + H₂O
Produces 34 ATP
TOTAL AEROBIC: 38 ATP per glucose
ANAEROBIC (without O₂):
In yeast: Glucose → Ethanol + CO₂ + 2 ATP
In plants: Glucose → Lactic acid + 2 ATP (rare)
[Much less efficient than aerobic]
HUMAN DIGESTIVE SYSTEM DIAGRAM:
Mouth → teeth grind, salivary amylase digests starch
│
Oesophagus → peristalsis moves food down
│
Stomach → HCl (pH 2), pepsin digests proteins
│ Churning creates chyme
Small intestine (6-7m):
├─ Duodenum: bile from liver (emulsifies fats)
│ pancreatic juice (amylase, lipase, trypsin)
└─ Ileum: villi absorb nutrients into blood
Lacteals absorb fatty acids → lymph
│
Large intestine (1.5m):
├─ Caecum with Appendix
├─ Colon: absorbs water, compacts waste
└─ Rectum: stores feces
│
Anus: expels feces
ENZYMES:
Salivary amylase → starch to maltose
Pepsin (stomach) → proteins to peptides
Trypsin (pancreas) → proteins to peptides
Lipase (pancreas) → fats to fatty acids + glycerol
Lactase → lactose to glucose + galactose
RESPIRATORY SYSTEM DIAGRAM:
Nose/Mouth → filters, warms, humidifies air
│
Pharynx → passage for food and air
│
Larynx → voice box, epiglottis prevents food entry
│
Trachea (windpipe) → C-shaped cartilage rings keep open
/ \
Left Right
Bronchus Bronchus
│ │
Bronchioles Bronchioles (smaller branches)
│ │
ALVEOLI (tiny air sacs, ~300 million in lungs)
● 1 cell thick wall
● Surrounded by capillaries
● O₂ diffuses into blood; CO₂ diffuses into alveoli
BREATHING MECHANISM:
INHALE: Diaphragm flattens down + Ribs move up/out
→ Chest volume increases → Air rushes IN
EXHALE: Diaphragm domes up + Ribs move down/in
→ Chest volume decreases → Air pushed OUT
Class 11 Biology complete NCERT notes — cell biology, biomolecules, cell division, plant kingdom, animal kingdom, morphology, anatomy, structural organisation, photosynthesis, respiration, digestion, breathing with diagrams.
62 pages · 2.3 MB · Updated 2026-03-11
Mitosis: 1 parent cell → 2 daughter cells with SAME chromosome number (diploid→diploid). Used for growth and repair. Occurs in somatic (body) cells. Meiosis: 1 parent cell → 4 daughter cells with HALF chromosome number (diploid→haploid). Used for sexual reproduction. Occurs in reproductive cells (gonads).
C3 plants: First stable product is 3-carbon compound (3-PGA). No Kranz anatomy. Less efficient in hot/dry conditions. Examples: Wheat, rice, oats, soybean. C4 plants: First stable product is 4-carbon compound (OAA). Have Kranz anatomy (bundle sheath cells around vascular bundles). Efficient photosynthesis at high temperature. Examples: Maize, sugarcane, sorghum.
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