sexual reproduction in flowering plants class 12 summary chapter 1

Sexual Reproduction in Flowering Plants - Class 12 Summary:

Flower Structure:

Sepals: Outermost floral parts, protect the flower bud.

Petals: Attract pollinators with colors and fragrances.

Stamens: Male reproductive organs, consist of anther and filament.

Carpels/Pistil: Female reproductive organ, consists of stigma, style, and ovary.

Pollen and Pollination:

Pollen Grains: Male gametophytes produced in anther.

Pollination: Transfer of pollen from anther to stigma.

Agents: Wind, water, insects, birds, and animals.

Double Fertilization:

Syngamy: Fusion of male gamete with egg cell.

Triple Fusion: Fusion of two male nuclei with two polar nuclei, forming the endosperm nucleus.

Seed and Fruit Formation:

Seed: Develops from fertilized ovule.

Fruit: Mature ovary containing seeds.

Types: Fleshy (apple, mango) or dry (pea pod, wheat grain).

Embryogenesis:

Zygote: Forms from the fusion of male and female gametes.

Embryo: Develops from the zygote within the seed.

Seed Germination:

Activation: Absorption of water and swelling of seed.

Radicle Emergence: First root emerges.

Shoot Development: Growth of shoot and emergence from the soil.

Apomixis and Polyembryony:

Apomixis: Asexual reproduction through seeds without fertilization.

Polyembryony: Development of multiple embryos within a seed.

Asexual Reproduction:

Vegetative Propagation: Reproduction through plant parts (runners, tubers, bulbs).

Advantages: Maintains genetic uniformity.

Seed Dormancy and Viability:

Dormancy: Period of inactivity before germination.

Viability: Ability of a seed to germinate under suitable conditions.

Artificial Hybridization and Plant Breeding:

Cross-Pollination: Transfer of pollen from one plant to the stigma of another.

Selective Breeding: Breeding plants for desired traits.