Which of the following occurred first in the creation of the moon ?
a) lava flows formed maria
b) earth and a planetesimal collided.
c) the moon became geologically inactive.
d) bombardment by meteoroids formed the highlands.

What would be the result if crossing over did not happen during meiosis in humans? a. there would be less genetic variation in humans. b. parents would be more likely to look like their children. c. the human population could not reproduce. d. children would have more chromosomes.

Consider the following reaction: 2h2 + o2 —> 2h2o a) what are the reactants in this reaction? b) what are the products in this reaction? c) how many molecules of oxygen are used in this reaction?

Sequence how oxygen accumulated in the atmosphere and the effect it had on life by completing the flowchart