CUET UG 2026
Biology Domain — Subject Code 304
SHORT NOTES
UNIT I: REPRODUCTION
~20% Weightage | ~10–11 Questions | ~50–55 Marks
Chapter 1: Sexual Reproduction in Flowering Plants
Flowering plants (Angiosperms) reproduce sexually. The flower is the reproductive organ.
1.1 Flower — The Reproductive Structure
• Bisexual (perfect) flower: has both stamen & pistil
• Unisexual flower: either stamen or pistil
– Male flower = Staminate; Female flower = Pistillate
Parts of a Stamen (Male):
• Filament + Anther (2 lobes, 4 microsporangia each)
• Anther wall layers: Epidermis → Endothecium → Middle layers → Tapetum
• Tapetum: Innermost nutritive layer; provides nourishment to developing pollen
Parts of Pistil (Female):
• Stigma (receives pollen) + Style + Ovary (contains ovules)
• Ovule contains: Nucellus, Integuments, Micropyle, Chalaza, Hilum, Funicle
⚡ CUET TIP: Tapetum is the MOST asked part of anther in CUET. Remember its function
— nourishment of developing pollen grains.
1.2 Microsporogenesis vs Megasporogenesis
Feature Microsporogenesis Megasporogenesis
Where Anther (microsporangia) Ovule (nucellus)
Cell Microspore Mother Cell (2n) Megaspore Mother Cell (2n)
Division Meiosis Meiosis
Product 4 Microspores (n) — Pollen 4 Megaspores (n) — 3 degenerate
Functional All 4 are functional Only 1 is functional
, 1.3 Pollen Grain Structure
• Two-layered wall: Exine (outer, sporopollenin) + Intine (inner, cellulose/pectin)
• Sporopollenin: Most resistant organic material known; present in exine; not destroyed by any
enzyme
• Pollen grain contains: Vegetative cell (large) + Generative cell (small, 2 male gametes)
• Pollen viability: few minutes (rice, wheat) to months (Rosa)
1.4 Female Gametophyte (Embryo Sac)
• Formed from functional Megaspore by 3 mitotic divisions → 8-nucleate, 7-celled structure
Structure of Embryo Sac:
Position Cells Count
Micropylar end Egg cell + 2 Synergids 3 cells
Centre Central cell (2 polar nuclei) 1 cell
Chalazal end Antipodal cells 3 cells
Total 7 cells, 8 nuclei
⚡ CUET TIP: The embryo sac has 7 cells but 8 nuclei — the central cell has 2 polar nuclei.
This is a very frequent CUET MCQ!
1.5 Pollination
Type Agent Examples
Autogamy Self (same flower) Cleistogamous flowers (Viola,
Commelina)
Geitonogamy Different flower, same plant Functionally cross-pollination
Xenogamy Different plant, same species True cross-pollination
Anemophily Wind Maize, grasses
Entomophily Insects Flowers with nectar, fragrance
Hydrophily Water Vallisneria, Hydrilla
Ornithophily Birds Bombax, Bignonia
• Cleistogamy: Flowers never open; guaranteed self-pollination; e.g., Viola, Oxalis
• Chasmogamy: Flowers open normally; allows cross-pollination
1.6 Pollen-Pistil Interaction & Double Fertilization
• Pollen germinates on stigma → pollen tube grows through style to ovule
Biology Domain — Subject Code 304
SHORT NOTES
UNIT I: REPRODUCTION
~20% Weightage | ~10–11 Questions | ~50–55 Marks
Chapter 1: Sexual Reproduction in Flowering Plants
Flowering plants (Angiosperms) reproduce sexually. The flower is the reproductive organ.
1.1 Flower — The Reproductive Structure
• Bisexual (perfect) flower: has both stamen & pistil
• Unisexual flower: either stamen or pistil
– Male flower = Staminate; Female flower = Pistillate
Parts of a Stamen (Male):
• Filament + Anther (2 lobes, 4 microsporangia each)
• Anther wall layers: Epidermis → Endothecium → Middle layers → Tapetum
• Tapetum: Innermost nutritive layer; provides nourishment to developing pollen
Parts of Pistil (Female):
• Stigma (receives pollen) + Style + Ovary (contains ovules)
• Ovule contains: Nucellus, Integuments, Micropyle, Chalaza, Hilum, Funicle
⚡ CUET TIP: Tapetum is the MOST asked part of anther in CUET. Remember its function
— nourishment of developing pollen grains.
1.2 Microsporogenesis vs Megasporogenesis
Feature Microsporogenesis Megasporogenesis
Where Anther (microsporangia) Ovule (nucellus)
Cell Microspore Mother Cell (2n) Megaspore Mother Cell (2n)
Division Meiosis Meiosis
Product 4 Microspores (n) — Pollen 4 Megaspores (n) — 3 degenerate
Functional All 4 are functional Only 1 is functional
, 1.3 Pollen Grain Structure
• Two-layered wall: Exine (outer, sporopollenin) + Intine (inner, cellulose/pectin)
• Sporopollenin: Most resistant organic material known; present in exine; not destroyed by any
enzyme
• Pollen grain contains: Vegetative cell (large) + Generative cell (small, 2 male gametes)
• Pollen viability: few minutes (rice, wheat) to months (Rosa)
1.4 Female Gametophyte (Embryo Sac)
• Formed from functional Megaspore by 3 mitotic divisions → 8-nucleate, 7-celled structure
Structure of Embryo Sac:
Position Cells Count
Micropylar end Egg cell + 2 Synergids 3 cells
Centre Central cell (2 polar nuclei) 1 cell
Chalazal end Antipodal cells 3 cells
Total 7 cells, 8 nuclei
⚡ CUET TIP: The embryo sac has 7 cells but 8 nuclei — the central cell has 2 polar nuclei.
This is a very frequent CUET MCQ!
1.5 Pollination
Type Agent Examples
Autogamy Self (same flower) Cleistogamous flowers (Viola,
Commelina)
Geitonogamy Different flower, same plant Functionally cross-pollination
Xenogamy Different plant, same species True cross-pollination
Anemophily Wind Maize, grasses
Entomophily Insects Flowers with nectar, fragrance
Hydrophily Water Vallisneria, Hydrilla
Ornithophily Birds Bombax, Bignonia
• Cleistogamy: Flowers never open; guaranteed self-pollination; e.g., Viola, Oxalis
• Chasmogamy: Flowers open normally; allows cross-pollination
1.6 Pollen-Pistil Interaction & Double Fertilization
• Pollen germinates on stigma → pollen tube grows through style to ovule
