2.3 interactivity: Understanding macromolecules

the supermassive black hole is in the middle of the galaxy.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added