Which of the following statements is correct? (2018)a)Ovules are not ...
Gymnosperms have naked ovule. Selaginella and Salvinia both produce two kinds of spores, macro (large) and micro (small) hence, called heterosporous. Equisetum (horsetail, scouring rush) is a pteridophyte. Stems are branched in Cedrus but unbranched in Cycas.
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Which of the following statements is correct? (2018)a)Ovules are not ...
Ovules are not enclosed by ovary wall in gymnosperms.
In gymnosperms, the ovules are not enclosed by an ovary wall, which distinguishes them from angiosperms. This is one of the key differences between the two groups of plants.
Explanation:
Gymnosperms and angiosperms are the two main groups of seed-producing plants. Gymnosperms include conifers, cycads, ginkgo, and gnetophytes, while angiosperms include flowering plants.
1. Ovules in gymnosperms:
Ovules in gymnosperms are not enclosed by an ovary wall. Instead, they are usually borne on the surface of specialized leaves called sporophylls. These sporophylls are arranged in cone-like structures, such as the cones found in conifers. The ovules are exposed and not protected by any additional structure.
2. Ovules in angiosperms:
In angiosperms, the ovules are enclosed within an ovary, which is a part of the flower. The ovary wall surrounds and protects the ovules. This arrangement allows for greater protection and efficient seed development.
3. Significance:
The fact that ovules are not enclosed by an ovary wall in gymnosperms is an important characteristic that sets them apart from angiosperms. This difference has implications for the reproductive strategies and adaptations of these plants.
4. Other options:
- Selaginella is heterosporous, while Salvinia is homosporous: This statement is correct. Selaginella, a type of clubmoss, produces two types of spores - microspores and megaspores, while Salvinia, a type of fern, produces only one type of spore.
- Horsetails are gymnosperms: This statement is incorrect. Horsetails, also known as Equisetum, are not gymnosperms. They belong to a separate group called fern allies.
- Stems are usually unbranched in both Cycas and Cedrus: This statement is incorrect. Cycas, a type of cycad, and Cedrus, a type of conifer, both have branched stems.
Therefore, the correct statement is option 'A': Ovules are not enclosed by ovary wall in gymnosperms.
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