We can see a candle flame at 30 miles on a clear, dark night, and we can hear the tick of a watch 20 feet away in a quiet room. These two facts are examples of .

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

Variety of living organisms; includes genetic, species, and ecological types.

How did the discovery of the rhesus factor affect society? o more patients died from having a transfusion with the wrong rhesus factor 0 new treatments during pregnancy could prevent harm to the developing child. o less donated blood could be used in the treatment of patients. the number of blood types was reduced by half