UPSC Civil Services Model Paper 3

Protozoa
● Protozoa mainly feed on bacteria, but they also eat other protozoa, and sometimes fungi. Hence statement 1 is correct.
● Some protozoa absorb food through their cell tissues.
● All protozoa digest their food in stomach-like compartments.
As they digest, they make and give off nitrogen, which is an element that plants and other higher creatures can use. Hence statement 2 is correct.
● Most protozoa do us no harm. But there are a few that cause diseases.
● One type of amoeba can live in human intestines.
◦ It feeds on red blood cells and causes a disease known as dysentery.
● Another species of protozoa can sicken hundreds of thousands of people when it gets into the tap water.
◦ Perhaps the best-known deadly protozoa cause malaria. Hence statement 3 is correct.