The most appropriate definition of an ovule/seed in terms of homologou...
Megasporangium" is a technical term given to an ovule, which contains nucellus, integuments and funiculus through which it is adhered to the placenta. In simple words, megasporangium along with its protective coverings, the integuments, is called ovule. Integuments cover an opening called micropyle, through which pollen tube enters the ovule during fertilisation. Thus, ovule is an integumented dehiscent megasporangium with single megaspore. So, the correct answer is C.
The most appropriate definition of an ovule/seed in terms of homologou...
Definition of an ovule/seed in terms of homologous structures:
An ovule is defined as an integumented indehiscent megasporangium with a single megaspore. In terms of homologous structures, an ovule is the structure that develops into a seed after fertilization in flowering plants. It is considered a homologous structure because it is derived from the same ancestral structure as the megasporangium found in non-flowering plants.
Explanation:
The process of seed formation begins with the development of an ovule within the ovary of a flower. The ovule is a structure that contains the female reproductive cells, including the egg cell. It is composed of several layers, including the integuments, which surround and protect the internal structures.
The ovule is considered a homologous structure because it is derived from the same structure found in non-flowering plants, known as the megasporangium. In non-flowering plants, the megasporangium is also an integumented structure that contains a single megaspore. However, in flowering plants, the megaspore undergoes further development and eventually becomes the female gametophyte.
During the process of fertilization, pollen grains are transferred to the stigma of the flower. The pollen tube grows down through the style and into the ovary, where it reaches the ovule. The male gametes travel through the pollen tube and fertilize the egg cell within the ovule. This fertilization event triggers the development of the ovule into a seed.
After fertilization, the ovule undergoes several changes. The integuments of the ovule develop into the seed coat, providing protection to the developing embryo. The megaspore within the ovule develops into the female gametophyte, which nourishes the developing embryo. The fertilized egg cell develops into the embryo, which eventually becomes the new plant.
In conclusion, the most appropriate definition of an ovule/seed in terms of homologous structures is an integumented indehiscent megasporangium with a single megaspore. This definition highlights the evolutionary relationship between the ovule in flowering plants and the megasporangium in non-flowering plants, emphasizing the homology between these structures.
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