O Level Biology 7 Views 1 Answers
Understand that after fertilisation the ovules develop into seeds and the ovary develops into a fruit
Understand that after fertilisation the ovules develop into seeds and the ovary develops into a fruit
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After fertilization in flowering plants (angiosperms), significant developmental changes occur that lead to the formation of seeds and fruits. Here’s a detailed overview of this process:
Development After Fertilization
- Fertilization:
- Following the successful fusion of sperm cells with the egg cell and the polar nuclei, fertilization occurs. This results in the formation of a zygote and the triploid endosperm.
- Ovule to Seed:
- Zygote Development: The zygote undergoes mitotic divisions, developing into an embryo within the ovule. This embryo will eventually become the new plant.
- Endosperm Formation: The triploid endosperm provides nourishment to the developing embryo. It serves as a food reserve, supplying essential nutrients during seed development and germination.
- Seed Coat Formation: The outer layers of the ovule develop into a protective seed coat (testa), which encases the embryo and endosperm, safeguarding them from environmental factors and pathogens.
- Ovary to Fruit:
- Ovary Development: After fertilization, the ovary begins to grow and mature into a fruit. This transformation is driven by hormonal changes, primarily involving auxins, gibberellins, and ethylene.
- Fruit Types: The type of fruit that develops can vary widely among species. Fruits can be classified into several categories:
- Fleshy Fruits: Such as berries, drupes (e.g., cherries), and pomes (e.g., apples), which have soft tissues.
- Dry Fruits: Such as legumes (e.g., peas) or nuts, which may be dehiscent (splitting open) or indehiscent (remaining closed).
- Function of Fruits:
- The primary role of fruit is to protect the developing seeds and aid in their dispersal once mature. Fruits can attract animals that eat them, thereby facilitating seed dispersal through feces or by attaching to fur.
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