The DNA molecule is mostly a covalently bonded molecule except between the nitrogen base Why is this important?

Ithink option a is correct because you cannot donate a different blood group than yours because it won't match.option a says betsy can donate to mark. they have the same blood group so donation can happen.

Diagrams for sure 67(8? ; 4

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.