Question

Draw a neat diagram of spirogyra and label on it:
Dark coloured and dot like structure generally present in the centre of the cell.

Answer 1

Hint:Spirogyra is a filament-like alga composed of spiral chloroplasts and many pyrenoids.

Complete answer:
To answer this question, first, we have to know about the structure and composition of spirogyra. Spirogyra belongs to green algae. They are mostly found in freshwater. A cell of spirogyra comprises a cell wall, pyrenoids, nucleus, cytoplasmic threads, spiral chloroplasts, and vacuole.

The labeled diagram of spirogyra is given below.

 Fig: A labeled diagram of spirogyra


Additional information:
In a microscopic view we can see the various parts of the cell of spirogyra. Cell wall is the outermost layer of a plant cell. Pyrenoid is a structure inside or beside the chloroplasts of definite algae, consisting mainly of ribulose bisphosphate carboxylase, one of the enzymes needed in photosynthesis for carbon fixation and sugar formation. Starch, a form of glucose storage, is often found around pyrenoids. Cytoplasmic strands are spindle-like strands found in all cells that also contain a nucleus. Vacuoles are membrane-bound sacs within a cell cytoplasm that function in a number of ways. Vacuoles can be very large in mature cells. They provide structural support and serve functions such as preservation, waste disposal, protection and growth to the cell.

Note: In spirogyra, chloroplasts create a spiral around the vacuole and have special bodies called pyrenoids. The nucleus is found in the middle of the cell. It is suspended from the strands of cytoplasm.