___________pass(es) from the maternal blood to the fetal blood. Fetal__________ pass(es) the other way.

A. The bicarbonate, phosphate, and protein: The major chemical buffer systems in the body are the bicarbonate, phosphate, and protein buffer systems.

B. Glucose is not a buffering system; it is a primary energy source.

C. Magnesium is a mineral with various physiological roles but not a major chemical buffer system.

D. Creatinine is a waste product of muscle metabolism, not a buffer system.

A. Two haploid (n) cells; four haploid (n) cells: At the end of meiosis I, the result is two haploid cells, each with half the number of chromosomes of the original cell. At the end of meiosis II, these two haploid cells divide again to form a total of four haploid cells.

B. Two diploid (2n) cells; one haploid (n) cell: This option is incorrect because meiosis I produces two haploid cells, not diploid cells, and meiosis II produces four haploid cells, not one.

C. Two diploid (2n) cells; four haploid (n) cells: This option is incorrect because meiosis I does not produce diploid cells; it produces two haploid cells. At the end of meiosis II, the result is four haploid cells, which is correct, but the description of meiosis I is incorrect.

D. Two haploid (n) cells; one diploid (2n) cell: This is incorrect because meiosis I results in two haploid cells, and meiosis II results in four haploid cells, not one diploid cell.