AP BIOLOGY

Detailed explanation-1: -Excretory organ of protozoa is the Contractile vacuole which is a multipart organelle that collects water from the cytoplasm and removes it from the cell. Contractile vacuoles excrete waste by diffusion method.

Detailed explanation-2: -Respiration in Protozoa: Protozoa do not have any organellae for the process of respiration. The limiting permeable membrane acts as a respiratory surface. The free molecular oxygen from the surrounding media enters into the body by diffusion. Presence of a cytochrome system has been demonstrated in protozoa.

Detailed explanation-3: -Protozoa move in the environment in three different ways: ameboid movement, flagella, and cilia. The ameboid movement is typical of ameboid protozoa (see below) and some other forms. Movement is achieved by cytoplasmic protrusions known as pseudopodia.

Detailed explanation-4: -Protozoa are single-celled eukaryotes that ingest food (algae and bacteria) by phagocytosis and generally move via pseudopods (flowing extensions of the plasma membrane) or whip-like flagella.