Скачать или смотреть Germination of Seed | Chap # 14 | Biology Class 10 | Lec # 9 (PTB)

Assalam-o-Alaikum

Germination of Seeds

Germination is a complex biological process that occurs when a seed, under suitable conditions, begins to sprout and grow into a seedling. It involves the reactivation of metabolic processes within the dormant seed.

Key Steps in Germination:

Water Absorption: The germination process starts when a seed absorbs water through its outer covering, the seed coat. This process is called imbibition and leads to the swelling and softening of the seed.

Activation of Enzymes: As the seed imbibes water, enzymes within the seed are activated. These enzymes break down stored nutrients (starches, proteins, and fats) into simpler forms that the developing embryo can use for growth.

Respiration Increases: Germination is an energy-intensive process, and the embryo requires more energy for growth. As a result, the rate of respiration increases, leading to the release of energy needed for cellular processes.

Radicle Emergence: The radicle, which is the embryonic root of the plant, is the first structure to emerge from the seed. It grows downward into the soil, anchoring the seedling and absorbing water and nutrients.

Plumule Growth: The plumule, which is the embryonic shoot of the plant, starts growing upward toward the soil surface. As it emerges, it develops into the stem and leaves of the young plant.

Photosynthesis Begins: Once the plumule emerges and develops leaves, the seedling can start photosynthesis. This process involves capturing sunlight and converting it into energy to fuel further growth.

Seed Coat Shedding: As the seedling establishes itself, the seed coat may be shed. In some cases, the cotyledons (seed leaves) become the primary source of energy until the plant becomes self-sufficient through photosynthesis.

Factors Affecting Germination:

Water: Adequate water is essential for the imbibition process to initiate germination.
Temperature: Optimal temperature ranges are necessary for enzyme activity and overall growth.
Oxygen: Oxygen is required for respiration, which provides energy for germination.
Light: Some seeds require light to germinate, while others may need darkness.
Seed Coat: The seed coat needs to be permeable to allow water uptake.


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