Carbon dioxide is a waste product carried by the back to the heart.

a : arteries
b : veins

answer: a. a gene that causes a specific trait.

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.

a ratio derived from the equality between two different units that can be used to convert from one unit to the other. information obtained from experiments, sometimes called experimental results. the part of the experiment that is affected by the independent variable.