The air we breathe is mostly a mixture of oxygen and nitrogen. How do air molecules change when they reach altitudes above 100 km? I need to make sure the answer I have is right.

Freckles are a dominant trait in humans. both of the girls have the genotype ff for freckles. if either one marries a man with no freckles, what are the chances that their children will have freckles?

Which level of taxonomy has the fewest organisms?

How many chromosomes are in a human gamete?