The Flower — Class 6 Science MCQs

The Flower | NCERT CBSE Curriculum

Practice 100+ MCQs on The Flower for Class 6 Science. Covers flower structure, parts (sepals, petals, stamens, pistil), pollination, fertilisation, and seed formation - with instant answers and performance report.

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Quick Revision: The Flower

  • Pedicel: The stalk that attaches a flower to the stem or branch. Flowers without a pedicel are called sessile flowers.
  • Thalamus: The swollen upper tip of the pedicel to which all floral parts (whorls) are attached.
  • Four Whorls of a Flower: (1) Calyx (sepals) — outermost, protects bud; (2) Corolla (petals) — attracts insects; (3) Androecium (stamens) — male reproductive part; (4) Gynoecium (pistil/carpel) — female reproductive part.
  • Accessory Whorls: Calyx and Corolla — only help in pollination, not directly reproductive.
  • Essential Whorls: Androecium and Gynoecium — directly involved in reproduction and seed formation.
  • Stamen: Male unit, consists of anther (produces pollen grains) and filament (stalk).
  • Pistil (Carpel): Female unit, consists of ovary (contains ovules), style (stalk), and stigma (sticky tip that traps pollen).
  • Complete vs Incomplete: Complete flowers have all four whorls; incomplete flowers lack one or more.
  • Unisexual vs Bisexual: Unisexual flowers have only stamens or only pistil (e.g., Papaya, Cucumber). Bisexual flowers have both (e.g., Hibiscus, Mustard).
  • Monoecious vs Dioecious: Monoecious — male & female flowers on same plant (Maize, Coconut). Dioecious — male & female flowers on separate plants (Papaya).
  • Pollination: Transfer of pollen grains from anther to stigma. Self-pollination (same flower/plant) vs Cross-pollination (different plants).
  • Agents of Pollination: Insects (bright petals, nectar, scent), Wind (feathery stigma, large pollen quantity), Water (e.g., Vallisneria — male flowers float to reach females).
  • Fertilisation: Fusion of male and female gametes to form a zygote. Pollen tube carries male gametes through style to ovule.
  • After Fertilisation: Ovary → Fruit, Ovules → Seeds, Petals/Stamens/Sepals → Wither and fall off.
  • Fruit Structure: Pericarp (fruit wall) has three layers: Epicarp (outer skin), Mesocarp (fleshy middle, e.g., mango pulp), Endocarp (inner hard layer, e.g., mango stone).
  • True Fruit vs False Fruit: True fruit develops only from ovary (e.g., Mango). False fruit develops from thalamus also (e.g., Apple, Strawberry).
  • Dry Fruit vs Fleshy Fruit: Dry fruit has thin, dry pericarp (Maize, Pea). Fleshy fruit has soft, pulpy pericarp (Mango, Orange).
  • Seed Structure: Seed coat (from integuments), Micropyle (tiny opening for water/oxygen), Hilum (scar where seed attached to fruit). Embryo consists of Radicle (young root), Plumule (young shoot), and Cotyledons (food storage).
  • Dicot vs Monocot Seeds: Dicots (Pea, Gram) — two fleshy cotyledons store food. Monocots (Maize, Rice) — one thin cotyledon, food stored in endosperm, seed coat fused with fruit wall forming a grain.
  • Seed Germination: Requires water (imbibition → swelling → coat ruptures), oxygen (respiration for energy), and suitable warmth. Epigeal — cotyledons come above soil (Bean). Hypogeal — cotyledons stay underground (Pea, Maize).
  • Seed Dispersal: By wind (wings/hair — Drumstick, Maple), water (spongy coat — Coconut, Lotus), animals (hooks/spines — Xanthium, Urena), explosive action (Poppy capsule).

Chapter Summary: The Flower

A flower is the reproductive part of a plant. It is attached to the stem by a stalk called the pedicel, with the thalamus at its tip holding all floral parts. A typical flower has four whorls: Calyx (sepals — protect the bud), Corolla (petals — attract pollinators), Androecium (stamens — male reproductive part with anther producing pollen), and Gynoecium (pistil — female part with ovary, style, and stigma). Calyx and corolla are accessory whorls, while androecium and gynoecium are essential whorls. Flowers may be complete or incomplete, unisexual or bisexual, and plants may be monoecious or dioecious.

Pollination is the transfer of pollen from anther to stigma, aided by insects, wind, or water. Fertilisation follows, where male and female gametes fuse to form a zygote. After fertilisation, the ovary develops into a fruit and the ovules become seeds. The pericarp (fruit wall) has three layers: epicarp, mesocarp, and endocarp. Seeds contain an embryo (radicle, plumule, cotyledons) and a seed coat with a micropyle for water entry. Dicot seeds store food in cotyledons, while monocot seeds store food in endosperm. Germination requires water (imbibition), oxygen, and warmth. Seeds are dispersed by wind, water, animals, or explosive action to prevent overcrowding and ensure species survival.

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