Question

8. Describe some of the diversity found in the cell structure of protists based on cell number, cell size, and the protective covering.

Answer 1

CELL NUMBER: Protist cells may contain a single nucleus or many nuclei.. Most protists are microscopic and unicellular, but some true multicellular forms exist. A few protists live as colonies that behave in some ways as a group of free-living cells and in other ways as a multicellular organism. Many protist cells are multinucleated.

CELL SIZE: Single protist cells range in size from less than a micrometer to thousands of square meters as observed in giant kelp.

PROTECTIVE COVERING: Animal-like cell membranes or plant-like cell walls envelope may be prersent in protist cells. In other protists, glassy silica-based shells or pellicles of interlocking protein strips encase the cells. The pellicle functions like a flexible coat of armor, preventing the protist from external damage without compromising its range of motion. Protective covering may also be linked to motility and also acts as light-sensityive organ in some cases. Eg: (a) Paramecium waves hair-like appendages called cilia to propel itself.

(b) Amoeba uses lobe-like pseudopodia to anchor itself to a solid surface and pull itself forward.

(c) Euglena uses a whip-like tail called a flagellum to propel itself.