Why has two different alleles for the same trait?

4. how does a phospholipid behave in water? the phosphate head does not mix with water; the fatty acid tails do. the phosphate head and the fatty acid tails mix with water. the phosphate head and the fatty acid tails do not mix with water. the phosphate head mixes with water; the fatty acid tails do not.

Which muscle is responsible for inhalation ?

Where is most of the fresh water on earth found a in the ocean b in glaciers and in ice caps c in rivers d in the soil