Final answer:
The mosquito is a multicellular organism with specialized cells and tissues for life functions, distinguishing it from the unicellular amoeba, bacteria, and Euglena where a single cell carries out all necessary activities for life.
Step-by-step explanation:
In the context of unicellular and multicellular organisms, the provided options show different types of organisms, but the one that does not rely on a single cell to perform all life functions is a mosquito. Amoeba, bacteria, and Euglena are all unicellular organisms. A mosquito, however, is a multicellular organism that depends on a system of specialized cells and tissues to perform its life functions, unlike the other options where a single cell carries out all the activities necessary for life.
Bacteria are single-celled organisms without cell organelles, classified as prokaryotes. On the other hand, amoebas and Euglena are more elaborate unicellular eukaryotes with organelles that perform functions analogous to multicellular organs.
While all life forms are composed of cells, the distinction lies in whether an organism relies on a single cell or a collective system of cells with specialized roles. Thus, the mosquito is as it has a multicellular structure, where different cells have differentiated to take on specific roles within the organism.