Which of the following statements about the interaction of earth’s systems is true?
a.
the interaction between earth’s systems is limited to a response to human activity.
b.
the earth’s system interact using positive feedback only.
c.
the earth’s systems interact using negative feedback only.
d.
all of the earth’s systems interact with each other.

Many animals cannot sweat to maintain a stable body temperature. what is one other way animals can cool down?

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 function does the limb sever in each animal? how are the limb bones of the four animals similar? based on these similarities what can be inferred about the evolution of the four animals.