ICSE Class 8 Answered

Reproduction in Spirogyra:

• Spirogyra reproduces sexually as well as asexually.
• Asexually it reproduces by fragmentation. The vegetative filament breaks into smaller fragments. Each fragment grows and produces a longer filament.
• Sexual reproduction occurs by a process known as conjugation, in which cells of two filaments lying side by side are joined by outgrowths called conjugation tubes.
• This allows the contents of one cell to completely pass into and fuse with the contents of the other.
• The resulting fused cell called the zygote becomes surrounded by a thick wall and overwinters, while the vegetative filaments die.

Reproduction in Mosses:

• Mosses reproduce sexually as well as asexually.
• Asexually, they can reproduce by regeneration and gemma formation.
• They regenerate a new plant from any plant parts such as protonema, shoot tips, leaves, and rhizoids.
• They also bear special structures called gemmae arising from the protonema. These are propagation bodies and can develop into new plants.
• Sexually reproduction comprises of two steps- formation of gametes which fuse to form a zygote followed by meiosis with the reduction of the chromosome number to produce haploid cells.