Reproduction in spirogyra - SS2 Biology Lesson Note

Spirogyra is a filamentous green alga that reproduces asexually and sexually. Let us explore the two modes of reproduction in Spirogyra:

1.       Asexual Reproduction: Spirogyra reproduces asexually through a process known as fragmentation or vegetative reproduction. The filamentous structure of Spirogyra consists of a chain of cells connected end to end. Asexual reproduction occurs when a filament breaks into smaller fragments, and each fragment grows into a new individual. The process of asexual reproduction in Spirogyra involves the following steps:

·         The filament undergoes cell division to form new cells along its length.

·         The cells elongate, and the protoplast (cell contents) divides into two, resulting in two daughter cells.

·         The cell walls between the daughter cells thicken, and a transverse wall (septum) is formed, separating the two daughter cells.

·         Each daughter cell develops a new cell wall and becomes an independent organism.

Asexual reproduction in spirogyra (byjus.com)

This fragmentation process allows Spirogyra to rapidly colonize new habitats and spread in freshwater environments.

2.       Sexual Reproduction: Spirogyra also reproduces sexually through a process called conjugation. Conjugation involves the exchange of genetic material between two filaments, leading to the formation of new cells with a mixed genetic composition. The process of sexual reproduction in Spirogyra involves the following steps:

·         Two adjacent filaments align side by side.

·         The cell wall between two corresponding cells dissolves, forming conjugation tubes or conjugation canals.

·         The protoplast (cell contents) of one filament extends through the conjugation tube and fuses with the protoplast of the adjacent filament.

·         The fused protoplasts exchange genetic material, resulting in the formation of new cells called zygospores.

·         The zygospores develop thick walls and become dormant.

·         Under suitable conditions, the zygospores germinate, forming new filaments, and the cycle continues.

Sexual reproduction in Spirogyra promotes genetic diversity, as the exchange of genetic material during conjugation results in new combinations of traits in the offspring.

Sexual reproduction in spirogyra (ask.learncbse.in)

Both asexual and sexual reproduction in Spirogyra contribute to its ability to adapt to different environments and ensure the survival and propagation of the species.