Answer:During pregnancy, red blood cells from the unborn baby can cross into the mother's blood through the placenta. If the mother is Rh-negative, her immune system treats Rh-positive fetal cells as if they were a foreign substance. The mother's body makes antibodies against the fetal blood cells
Explanation:
In aquatic plants, water passes among the tissues and provides the medium for gas exchange. In terrestrial plants, air enters the tissues, and the gases diffuse into the moisture bathing the internal cells.
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Answer:
Homeostasis typically involves negative feedback loops that counteract changes of various properties from their target values, known as set points. In contrast to negative feedback loops, positive feedback loops amplify their initiating stimuli, in other words, they move the system away from its starting state.