Oceanic crust is composed mainly of basalt .continental crust is composed mainly of granite .why does oceanic crust generally tend to subduct under continental crust when plates collide

What molecules will be best used to compare different species with the exact same sequence of amino acids? why would two species have the same protein even if the molecules in question is different? (hint: transcription to translation to protein).

An animal cell (left) and a plant cell (right) are shown.which organelle, labeled x in the diagram, is found in both plant and animal cells?

Currents are caused by temperature and density differences