Iwill mark brainliest for the first correct answer!
which structure could be found in a single-celled organism?
internal organs
legs and feet
large brain
outer covering

Explanation:

Eubacteria are the single-celled organisms that humans are most used to dealing with because they are found in the oxygen-rich, temperate environment we ourselves require to survive. Protists' internal cellular structure is more complex than bacteria

humans can cause extinction of a species through overharvesting, pollution, habitat destruction, introduction of invasive species (such as new predators and food competitors), overhunting, and other influences. explosive, unsustainable human population growth is an essential cause of the extinction crisis.

explanation:

i didn't have the answer choices , but i tried my best.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme