A biological system is a complex network of biologically relevant entities. ... Examples of biological systems at the macro scale are populations of organisms. On the organ and tissue scale in mammals and other animals, examples include the circulatory system, the respiratory system, and the nervous system. source: google
Genetic drift is the dramatic almost sped up process of natural selection due to the untouched habitat the species I lives in. Genetic drift is characterized by the changing in alleles, whether more or less, natural selection could care less as long as they're creating diverse populations.
B, Provide nutritional support to the embryo. It is not D, as the breasts are not part of the female reproductive system. It isn't C because during pregnancy, fetal and maternal blood do not mix. It also isn't D since women do not produce sperm.
Answer:
A, C
Explanation:
mucus acts as a barrier! all of the other things mentioned (D and E) are caused by white blood cells.
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