Clitellum of pheretima is thick girdle that isa)Nonglandular around 14 - 16 segmentsb)Glandular around 14 - 16 segmentsc)Glandular around 16 - 18 segmentsd)Nonglandular around 16 - 18 segmentsCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Clitellum is a glandular tissue present in the segment 14-16

Answer

Earthworm belongs to phylum Annalisa. as per ncert clitellum of pheritima is thick girdle that is  glandular around 14,15,16 segments. these glands helps in cocoon formation during breeding season. finally answer is option 'B'...

Answer

It is clearly mentioned in NCERT Book and obviously b will be the correct answer

Answer

Clitellum of Pheretima
The clitellum of Pheretima, also known as the reproductive girdle, is a thickened glandular structure that is located near the anterior end of the earthworm's body. It plays a crucial role in the reproduction of the earthworm.

Glandular Structure
- The clitellum of Pheretima is glandular and is present around 14 - 16 segments of the earthworm's body.
- The glandular cells in the clitellum secrete a mucous substance that helps in the formation of the cocoon during reproduction.
- This mucous material contains eggs and sperm cells, which are deposited into the cocoon for fertilization.

Reproductive Function
- During mating, two earthworms align their ventral surfaces and exchange sperm cells.
- The sperm cells are stored in the seminal receptacles of the earthworm and are later released into the cocoon during the formation process.
- The cocoon is secreted by the clitellum and is deposited in the soil for the development of the earthworm embryos.

Importance of Clitellum
- The presence of a glandular clitellum in Pheretima indicates its role in reproduction.
- The secretion of mucous material and the formation of the cocoon are essential for the successful fertilization and development of earthworm embryos.
- The thick girdle structure of the clitellum provides protection to the developing embryos and ensures their survival in the soil environment.
In conclusion, the glandular clitellum of Pheretima is a vital reproductive structure that facilitates the process of fertilization and cocoon formation in earthworms. Its presence around 14 - 16 segments highlights its significance in the reproductive biology of these organisms.

Answer

The sexual cycle involves the following three steps:
(i) Fusion of protoplasms between two motile or non-motile gametes called plasmogamy.
(ii) Fusion of two nuclei called karyogamy.
(iii) Meiosis in zygote resulting in haploid spores.

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