1. natural selection acts on existing traits because you can not evolve into something you didn't have
2. original structures evolve to accomplish new function in order to survive
Explanation:
Nonrenewable energy resources include coal, natural gas, oil, and nuclear energy. Once these resources are used up, they cannot be replaced, which is a major problem for humanity as we are currently dependent on them to supply most of our energy needs.
Answer:
Due to the earth's rotation and the gravitational pull of the moon.
Answer:
) Presence of specific glycoproteins on the cell membrane
Explanation:
When specif glycoproteins(antigens) or antibody are present on a cell membrane of Red blood cell,they can be used to identify the blood type.Antigens are substances capable of triggering an immune response in a cells.
In addition,they function in transport of molecules across the RBC. They help in the maintenance of the RBC,and aiding the arrest of cells capable of causing diseases to the body.
Therefore,they are good determinants of blood types,based on this two types of antigens present in a blood type.
These two antigens used for classification of blood types are the 1-the ABO antigens 2,the Rhesus antigens.
Essentially,when a WBC produces an antibody ,which is a molecule that defends the body,If this is not compatible,the antibody will recognize it as a foreign body and attack it.Thus such blood types are not compatible. Thus the antibody-antigen reaction are good for knowing and classify blood types.
Antigen can also be glycoprotein,carbohydrate or glycolipids.
Generally blood types are inherited from both parents.Therefore the antigen present on the RBC are combination of the alleles from each parent.
