How large was Biosphere 2? A.
1 acre
B.
3 acres
C.
10 acres
D.
25 acres

People who exercise for an hour may have lower cholesterol levels. is that a statement? a law? or a hypothesis?

When analyzing tree rings, what do scientists assume a thin ring indicates?

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.