NEET BIOLOGY

Detailed explanation-1: -Protists recycle sewage and waste materials. Algal blooms are harmful when overgrown-deplete water of nutrients consequently killing fish.

Detailed explanation-2: -Larger phytoplankton are single-celled algae also known as protists-tiny organisms that also contain chloroplasts. Many photosynthetic protists are capable of movement and some also hunt and eat other single-celled organisms.

Detailed explanation-3: -Protists like zooxanthellae have a symbiotic relationship with coral reefs; the protists act as a food source for coral and the coral provides shelter and compounds for photosynthesis for the protists.

Detailed explanation-4: -Protists, along with bacteria and fungi, produce most of the oxygen on our planet through photosynthesis.