Question

The filament of spirogyra aplanospore is observed. One of the filaments has 150 cells and another contains 225 cells. If all the cells in both the filaments are involved in asexual reproduction, what is the ration of new filaments developed from them?
A 1:1
B. 3:5
C. 1:5
D. 2:3

Answer 1

Hint: Spirogyra belongs to kingdom Plantae, and found in clear eutrophic water, it is filamentous structure, spirogyra possesses cell wall, nucleus, spiral chloroplast and nucleus. It can reproduce both sexually and asexually.

Complete answer:
The spirogyra is also called as water silk and blanket weed, it is filamentous green algae (charophyte). There are more than 400 species of spirogyra and due to the presence of spiral chloroplast, it is named spirogyra.

The asexual reproduction occurs by the formation of akinetes, azygospores and aplanospores.
• In Akinetes, The filament cell develops into a thick-walled structure, under unfavourable conditions, such a cell called akinetes. During the favourable condition, these thick walled structures develop into new plants.

• Aplanospores is an oval non-motile structure that produces a new plant under favourable conditions.

• When the fusion of gametes does not take place, due to sudden change in environment then these function as a zygospores.

Asexual reproduction takes place mainly through fragmentation of filaments, so that filament split into two fragments and the ratio of new filament will be 1:1, it does not depend on the number of cells in the filament.

The sexual reproduction takes place by conjugation process, which is of two types, such as lateral conjugation that occurs between two adjacent cells of same filaments and the other one is scalariform conjugation in which two filaments are involved which are recently formed.

Hence, the correct answer is option (A).

Note: In spirogyra algae the sexual reproduction of the lateral conjugation is of further two types, such as direct lateral conjugation, in which male gametes pass via aperture and enter the female gametangium and fuse to form a zygospore. While indirect lateral conjugation, on both sides conjugate tubes form over the transverse septum and then male gametes pass to the female gametes and fuse to form zygospores.