Question

Which algae is commonly called as pond silk or pond scum?

• A. Volvox
• B. Chlamydomonas
• C. Euglena
• D. Spirogyra

Answer 1

Answer: (D)

Spirogyra is a freshwater alga found freely floating on the surface of the stagnant pools, ponds and ditches, etc. It is commonly known as water silk or pond silk. It is a unbranched filament. All the cells are alike and arranged in a single row. The cells are cylindrical, longer broad. The cell wall is two layered; the outer layer is of pectic substance and the inner of cellulose. Inside the cell, cytoplasm is present which surrounds a large central vacuole. There is a large single nucleus present in the center of the cell. The nucleus is held by cytoplasmic strands. The most characteristics feature of the cell is the ribbon or strap-shaped chloroplasts spirally arranged. The number of chloroplast varies from 1 to 16. There are many pyrenoids are present on the chloroplast.