Amoeba & Protozoans: Movement & Structure — NEET Biology
📚 Practice ConceptMarine forms have silica shells on their surface. Some of them such as Entamoeba are parasites.
Which of the following statements about Kingdom Protista are correct? S1: Diatoms have cell walls embedded with silica, making them indestructible, and are considered chief producers in oceans. S2: Dinoflagellates are mostly marine, photosynthetic organisms with stiff cellulose plates on their outer surface and two perpendicularly arranged flagella. S3: Euglenoids possess a protein-rich pellicle for flexibility and exhibit mixotrophic nutrition, being photosynthetic in sunlight and heterotrophic otherwise. S4: Slime moulds are saprophytic protists that form large aggregations called plasmodium under suitable conditions, and their spores possess true walls resistant to adverse conditions. S5: Amoeboid protozoans are exclusively marine organisms that use cilia for locomotion and prey capture. S6: Ciliated protozoans, like Paramoecium, use thousands of cilia for active movement and possess a gullet that opens to the outside of the cell surface to steer food.
View solution & NCERT explanation
Correct answer: B — S1, S2, S3, S4 and S6 are correct
The question tests the understanding of characteristics of different groups within Kingdom Protista. S1: Correct. Diatoms have cell walls embedded with silica, making them indestructible, and they are the chief producers in the oceans. S2: Correct. Dinoflagellates are mostly marine, photosynthetic, have stiff cellulose plates on their outer surface, and possess two flagella, one longitudinal and one transverse. S3: Correct. Euglenoids have a protein-rich pellicle instead of a cell wall, which makes their body flexible. They are photosynthetic in sunlight but behave as heterotrophs by preying on smaller organisms when deprived of sunlight. S4: Correct. Slime moulds are saprophytic protists that form plasmodium under suitable conditions. Their fruiting bodies bear spores with true walls, which are extremely resistant. S5: Incorrect. Amoeboid protozoans live in fresh water, sea water, or moist soil. They move and capture prey using pseudopodia (false feet), not cilia. Marine forms have silica shells on their surface, indicating they are not exclusively marine and some do possess shells. S6: Correct. Ciliated protozoans are aquatic, actively moving organisms due to thousands of cilia. They have a gullet that opens to the outside, and coordinated ciliary movement steers food into it. Therefore, statements S1, S2, S3, S4, and S6 are correct. The tested concept is the distinguishing features of various protistan groups.
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