Fixation answer : hope this helps
Nucleic acids would be the answer to your question
Well, the high energy and heat found in the photons of sunlight allow plants to make their own food, sustaining them long enough to be eaten by us, or to be eaten by animals about to be eaten by us. Plus we get direct warmth from the sun. These things mean that the sun is what keeps all organisms alive in the first place.
Adenine pairs with thymine. They form complementary pairs withone another during replication of the parent strand, forming the complement strand. If thymine is present for 30% of the bases, then its complement, adenine, will also be present in 30% of the bases.
Gravity
Plant roots always grow downward because specialized cells in root caps detect and respond to gravity. This is an example of a tropism. A tropism is a turning toward or away from a stimulus in the environment. Growing toward gravity is called geotropism.
