What is a unicellular organism that can carry out its own life functions?

Amoeba is indeed a unicellular organism capable of carrying out all its necessary life functions independently. Being a single-celled organism, an amoeba can perform processes such as respiration, nutrition, excretion, and reproduction within its own cellular structure. This ability allows it to maintain homeostasis and perform functions essential for survival without the need for other cells.

Amoebas move and obtain food through a process called phagocytosis, where they extend parts of their body to engulf and digest prey. This demonstrates their capability to adapt and thrive in various environments, making them a perfect example of a self-sufficient unicellular organism.

The other options, while they also represent unicellular organisms, may not capture the essence of carrying out all necessary life functions in the same context. Paramecium and bacteria are both unicellular and perform life functions, but the broad term protozoa encompasses various organisms, not limited to those functioning independently in the same way as an amoeba.