Blood calcium concentration is maintained relatively constant even when calcium intake increases. based on this information, one can conclude that:
a. blood calcium must be needed for the normal function of many cells.
b. the blood calcium concentration must be controlled by the nervous system.
c. there must be a mechanism to detect the concentration of calcium in the blood.

What is the difference between sex-linked traits and autosomal traits in humans? a. sex-linked traits can only be passed from fathers to sons, while autosomal traits can be passed on from both parents to offspring of any sex. b. sex-linked traits are passed on through the x and y chromosomes, while autosomal traits are passed on through the other 22 chromosomes. c. sex-linked traits only affect females, while autosomal traits affect both males and females. d. sex-linked traits refer to genes that are on the x and y chromosomes, while autosomal traits refer to genes on all 23 chromosomes.

Eutrophication caused by human nutrient pollution.

Approximately what wavelength of light is best absorbed by chlorophyll a