Which organism behaves like plants in the presence of light and absence of organic food,but in reverse conditions behaves like animals?

Nosema belongs to which phylum?

The posterior end of $Amoeba$ is characterized by:

What is the meaning of the term $Protozoa$?

Trichocysts take part in:

Two species of Amoeba $X$ and $Y$ were kept in fresh water and adapted to it. Species $X$ developed a contractile vacuole. When both were transferred to sea water and adapted,both $X$ and $Y$ lost their contractile vacuole. From these observations,we conclude that: