15. Where do most scientists today predict that the earliest cells lived? a) Deep in isolated salt lakes
b) Around hydrothermal vents
c) Places where lightning strikes are most common
d) Mars, or perhaps a comet

At which location in earth’s interior does the top density continue to increase as thickness decreases?

Which of the following describes a negative feedback loop? when the heart rate is too high, the body sends hormones that continually increase the heart rate higher. when a pregnant woman is in labor, the body sends hormones that increase the intensity of contractions, which then increases the secretion of the same hormones. when blood sugar is too low, the body sends hormones that raise blood sugar until it reaches a typical level and hormone secretion slows. when a person is jogging, the body sends hormones that continually decrease the rate of oxygen supply to the legs.

What class of levers is shown in this image?