30
which statement describes the condition of the heart at the point indicated in the electrocardiogram?

a. the atria are contracting and pushing blood into the bottom ventricles of the heart.

b. the valves of the aorta and pulmonary artery close, producing the first heartbeat.

If bacteria are much too small to see, what is one reason why can we see colonies in the petri dishes that have plenty of food to eat after only a few days?

Humans are believed to have evolved in coastal regions in east africa. the region had an abundant supply of fish for early humanoids to eat. when scientists analyze the fads gene they see an interesting pattern. people whose families have lived in this area of east africa for generation show a high level of diversity in alleles for the fads gene. conversely, people whose families had migrated inland a moderate distance from sources of fish showed a much lower diversity for fads gene alleles. additionally, the fads alleles found in people whose family has lived inland for generation are almost all gene alleles which produce fads proteins with a high level of function and activity. how do anthropologists explain this?

Indicate the coat color and the proportion of offspring with that color for each of the following crosses of rabbits. assume all are homozygous. chinchilla x albino a) all chinchilla b) 1/2 chinchilla, 1/2 albino c) 3/4 chinchilla, 1/4 albino