How does reproductive isolation affect the evolution of a species

Assume that a student is given two different models of bacteria, with one model consisting of big bacteria and the other consisting of small bacteria. how can the student demonstate the theory of endosymbiosis using the models

The deserts of the sahara and australia are associated with

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.