Which is the best defithe lock-and-key mechanism refers tonition of activation energy?

What causes darkening of the skin as melanin production increases

How do the evolutionary chart and the video support the claim that all living things are made up of cells?

Which statements explains what the fossil records indicates? check all that apply. a) earth is 4.5 billion years old b) many organisms have become extinct c) mammals have always existed on earth d) mass extinctions have occurred several times on earth e) the amount of water on earth has decreased over time?