Question

"Keiselgurh" a heat resistant material is obtained from

• A. Red algae
• B. Brown algae
• C. Diatoms
• D. Fungi

Answer 1

The correct option is C Diatoms

Cell of Diatoms are surrounded by cell wall, frustules, which has silica deposits. 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. Extraction, grounding, sieving and sinteration of diatomaceous earth obtain Keiselguhr which is used in filtration techniques. Presence of silica makes it chemically inactive and heat resistant. Calcium carbonate is present in cell wall of red algae; it makes the cell permeable to small molecules but impermeable to macromolecules. Red algae secrete calcium carbonate shells which are accumulated in sea bottom and forms red corals. The cell wall of Brown algae has an inner cellulose layer and outer gelatinous coat which is composed mainly of algin; it is used as emulsifymg agent and a stabilizer. Fungal cell wall is composed of chitin and lack cellulose. Correct answer is option C.