Question

The diatoms do not easily decay like most of the other algae because

• A. They have water proof cells.
• B. Their walls are mucilagenous.
• C. They have highly siliceous wall.
• D. They are non-living.

Answer 1

The correct option is C They have highly siliceous wall.

Diatoms are unicellular eukaryotes placed under kingdom Protista; option D is incorrect. Cell of Diatoms are surrounded by cell wall having two parts or frustules; frustules make two overlapping halves (the epitheca and the hypotheca). Presence of numerous tiny pores in frustules connects the protoplast of the cell with the outside environment; this makes option A incorrect as their wall are in contact with surrounding water through pores. The pectic substance of cell wall is richly impregnated with silica, which creates patterns of minute perforations and striations. Around 90 percent of diatomaceous cell wall is silica. Shells of diatoms are highly resistant to decomposition due to presence of silica and are deposited in ocean beds leading to formation of diatomaceous earth. This makes option B incorrect and option C correct. Thus, the correct answer is option C.