Ciliates differ from all other protozoans in
- having a contractile vacuole for removing excess water
- having two types of nuclei
- using flagella for locomotion
- using pseudopodia for capturing prey
Answer
(2) having two types of nuclei
Solution
Ciliated protozoans (e.g., Paramoecium) are actively moving organisms with thousands of cilia and a gullet that opens to the outside.
They are unique among protozoans in having two types of nuclei — a large macronucleus (vegetative functions) and a small micronucleus (reproduction) ⇒ nuclear dimorphism.
Contractile vacuoles also occur in other freshwater protozoans (e.g., Amoeba); flagella are used by flagellated protozoans and pseudopodia by amoeboid protozoans.
Answer: (2)