write a tall note on seed and fruit formation
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Answer:
NOTE ON SEEDS
A seed is an embryonic plant enclosed in a protective outer covering. The formation of the seed is part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants.
Seeds are the product of the ripened ovule, after fertilization by pollen and some growth within the mother plant. The embryo is developed from the zygote and the seed coat from the integuments of the ovule.
Seeds have been an important development in the reproduction and success of gymnosperm and angiosperm plants, relative to more primitive plants such as ferns, mosses and liverworts, which do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates.
The term "seed" also has a general meaning that antedates the above – anything that can be sown, e.g. "seed" potatoes, "seeds" of corn or sunflower "seeds". In the case of sunflower and corn "seeds", what is sown is the seed enclosed in a shell or husk, whereas the potato is a tuber.
Many structures commonly referred to as "seeds" are actually dry fruits. Plants producing berries are called baccate. Sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Different groups of plants have other modifications, the so-called stone fruits (such as the peach) have a hardened fruit layer (the endocarp) fused to and surrounding the actual seed. Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed, such as an acorn or hazelnut.
NOTE ON FRUIT FORMATION
After pollination and fertilization, carpels develop into the fruit tissue we eat (ovary) and the seeds within (ovules). Fruit development is initiated by growth regulating hormones produced by developing seeds. Because carpels ultimately develop into fruit tissue, the number of carpels in a flower determines the degree to which pollination and seed development is required to produce fruit. Flowers with one carpel only require fertilization of one of the two ovules to produce fruit. In contrast, species with multiple fused carpels require fertilization of a smaller proportion of the total ovules within a flower for fruit development. The growth regulating hormones produced by a subset of the total possible seeds are sufficient to initiate the development of fused carpels into fruit. As a result, normal fruit development is less dependent on seed development in species with multiple fused carpels.
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Explanation:
Seeds and fruits are formed by fertilization. In angiosperms, two structures are formed as a result of double fertilization – a diploid zygote and a triploid primary endosperm cell. The zygote develops into an embryo, whereas, the endosperm cell gives rise to endosperm. It provides nourishment to the growing embryo. Both fruits and seeds are an important part of angiosperms.
Let us have an overview of the significance of fruits and seeds in detail.
Significance of Seed Formation
Following are the significance of seed formation:
Dependable Method
Seed formation is a dependable method. This is because pollination and fertilization of seed plants does not require water.
Perrenation
Seeds are dry and have a dormant embryo with a thick protective seed coat. Thus it is suitable for perrenation during unfavourable conditions.
Dispersal
Seeds have the ability to disperse to a new habitat and colonise there.
Reserve Food
Seeds contain reserved food for nourishing the young seedlings until they are capable of producing food on their own.
Variations
Seeds are produced by sexual reproduction. Due to this, they carry a number of variations which helps them to adapt to different environmental conditions.
Storage
Seeds have stored food supply throughout the year, especially during unfavourable conditions.
Also Read: Seed Formation
Significance of Fruit Formation
Following are the significance of fruit formation:
Protection
The developing fruits protect the seeds from unfavourable conditions, mechanical injury and pests.
Dispersal
Fruits help in the dispersal of seeds to distant places.
Animal Food
Fleshy fruits are eaten by animals who also disperse the seeds to other places.
Provide Nutrition to Germinating Seeds
Some fruits also provide nutrition for developing and germinating seeds.
Important for Humans
Fruits are an important source of food, organic acids, vitamins, minerals, proteins, oil and sugar.