Stage 1: Diagram Component Identification:
The diagram illustrates three primary components involved in plant fertilization: A: Stigma – The pollen-receptive apex of the pistil. B: Pollen tube – A conduit extending from the pollen grain, facilitating male gamete delivery to the ovule. C: Ovule – The ovarian structure housing the egg cell (female gamete).
Stage 2: Pollination Process:
Pollination, the inaugural step in fertilization, involves pollen grains (containing male gametes) depositing onto the stigma (A), mediated by agents such as wind or pollinators.
Stage 3: Pollen Tube Elongation:
Upon alighting on the stigma, a pollen grain germinates, initiating the growth of a pollen tube (B). This tube traverses the style to the ovary, establishing a route for male gametes to reach the ovule.
Stage 4: Fertilization Event:
As the pollen tube (B) reaches the ovule (C) within the ovary, male gametes are introduced, leading to fertilization. The fusion of a male gamete with the ovule's egg cell produces a zygote.
Stage 5: Outcome:
Fertilization culminates in zygote formation, which develops into a seed. The ovule matures into a seed, capable of germinating into a new plant.
