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Plant Structures

Problems

The Seed

Roots

Problem : What are the three components of a seed?

A seed consists of an embryo, food source, and protective seed coat.

Problem : The embryonic food sources for angiosperms and gymnosperms arise from different origins. What are they?

The food source for an angiosperm seed is derived from the triploid nucleus formed during double fertilization* {bio/plants/plantclassification}*, which becomes the endosperm. The food source for a gymnosperm seed, on the other hand, is derived from the tissue of the female **gametophyte.

Problem : How is the seed an adaptation that has helped terrestrial plants make the transition from an aqueous environment?

The seed prevents the plant embryo from drying out on land; the seed can also lie dormant until environmental conditions are optimal for germinating, thereby circumventing the problem of an uncertain and ever changing terrestrial environment.

Problem : Describe two ways in which an angiosperm seed is different from a gymnosperm seed.

The food source of an angiosperm seed comes from endosperm, while gymnosperms rely on the tissue of the female gametophyte. A second difference is that angiosperm seeds are encased in protective ovaries, which help prevent desiccation and aid in seed dispersal.

Problem : What is an ovary and what is its function in plants?

An ovary, which is derived from carpels on the flower, encases the ovules, where the egg cells are produced and develop. After fertilization, the ovary develops into a fruit, which gives the developing embryo added protection against desiccation and aids in its dispersal by wind and animals.

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