Easy. Answer is oxygen because it says which one was missing before any life was on earth. And in order to have life on earth you need oxygen!
:)
Shelled protozoans became part of 7 layers
Answer:
Point mutation is the correct answer.
Explanation:
Sickle cell disorder is a genetic disorder that is caused because of point mutation.
Due to point mutation protein lose their function which results in sickle cell disease.
The mutation in the Hemoglobin Subunit Beta gene in Sickle cell diseases affects the hemoglobin and the red blood cells molecules that transfer oxygen to the cells.
Sickle cell diseases can lead to stroke, organ damage,blindness, priapism,hypertension, acute chest problems.
Molecules of mRNA are composed of relatively short, single strands of molecules made up of adenine, cytosine, guanine and uracil bases held together by a sugar phosphate backbone.
Hope This Helps, Lexi
B. Controlling the flow of Blood to the skin seems to make the most sense
