AP BIOLOGY

Detailed explanation-1: -Bundles of flame cells are called protonephridia. So the correct option is ‘Flatworm rotifers, earthworm’.

Detailed explanation-2: -A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates, including flatworms, rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.

Detailed explanation-3: -Protonephridia is found in primitive invertebrates such as flatworms and consists of flame cells. On the other hand, metanephridia are found in higher invertebrates, such as earthworms, and they lack flame cells.

Detailed explanation-4: -Protonephridium is an excretory tube that lacks an internal opening. It is found in Platyhelminthes, Rotifers, and some Chordates.

Detailed explanation-5: -Flatworms have protonephridia or flame cells that help in excretion.