During conjugation in $Paramecium$,which of the following events occurs?

In which group of organisms does the cell wall form two thin overlapping shells that fit together?

Nosema belongs to which phylum?

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'.

Give scientific reasons: Euglena is also called a plant-animal.

Which of the following is an incorrect pair?