Chemoreceptors in the circulatory system detect changes in circulating pCO2. If CO2 concentrations get too high, the rate of ventilation increases. Why does this make sense?
A. It makes sense because CO2 is formed from O2 and, therefore, CO2 is a sign that oxygen is being consumed.
B. It makes sense because tissues that are more actively working produce more CO2 and, therefore, need more O2.
C. Actually, it does not make sense. There is no relationship between CO2 and ventilation rate.
D. It makes sense because hemoglobin carries CO2 and, therefore, blocks oxygen binding to the heme site, creating an oxygen deficiency.

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.

Cells destroy body cells infected by a virus or bacteria.