Chapter 18, Problem 1RQ

Summary Introduction

To write:

The forms of sexual and asexual reproduction occurring in the green algae.

Introduction:

Green algae belongs to the Phylum called the Chlorophyta consisting of the chloroplasts with chlorophyll a and b. They can be unicellular or multicellular inhabiting the freshwater, marine and terrestrial habitats. They reproduce both asexually and sexually.

Explanation of Solution

Vegetative reproduction in green algae occurs by fragmentation. In fragmentation, the body portions of the algae is separated giving rise to new individuals.

Asexual reproduction in Chlorophyta involves only one parent and occurs by the formation of zoospores or aplanospores. Zoospores are motile and aplanospores are non-motile. Both the spores on germination gives rise to new algae.

Sexual reproduction takes place through the formation and fusion of the two gametes. Sexual reproduction can isogamous, anisogamous or oogamous. In isogamy, the fusion of the gametes which are morphologically identical with similar size and structure takes place. Example: Spirogyra. Anisogamy is the fusion of two gametes of different size. Example: Chlamydomonas. In oogamy, fusion occurs between one large, non-motile female gamete with a smaller, motile male gamete. Example: Volvox.

The fusion is gametes results in the formation and the germination of the zygote by meiosis.

Conclusion

The asexual reproduction in green algae is by the formation of zoospores or the aplanospores and sexual reproduction occurs by the fusion of the gametes.