What causes heart ventricles to fill with blood?

i. atrial contraction

ii. closing of atrioventricular valves

iii. opening of semilunar valves

a. i only

b. i and ii only

c. ii and iii only

d. iii only

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? a) catalysis b) metabolism c) anabolism d) dehydration e) catabolism

Which of the following can occur to two segments of a population if they are geographically isolated 1.) they can only share some types of genes 2.)both groups most likely become extinct 3.)they find a way to come back together 4.)eventually they become separate species