Unicellularity is a characteristic of

Why do diatoms float on the surface of water?

Which of the following groups of kingdom $Protista$ is being described in the statements given below?
$(i)$ This group includes diatoms and golden algae.
$(ii)$ They are microscopic and float passively in water currents (plankton).
$(iii)$ Most of them are photosynthetic.
$(iv)$ They have deposits in their habitat; this accumulation over billions of years is referred to as 'diatomaceous earth'.

Passive food ingestion in $Amoeba$ is known as

Write the characteristic features of the group Dinoflagellates.

Which one of the following represents the class $Mastigophora$?