This is a model of one molecule of an element. Use the model for questions 16-20.
(Note: all neutrons, protons, and electrons
are showing in the drawing. None are hidden
from the eye.)

16. How many electrons does this
element have?
17. How many protons does this
element have?
18. How many neutrons does this element have?
19. How many electrons are in the second level?
20. What is the atomic number of this element?

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i. e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).

After frida stops exercising, she continues to breathe heavily. what is most likely occurring in her body? heavy breathing during exercise has produced an oxygen surplus in her muscles. this oxygen is being transported to her lungs. this is a result of aerobic respiration. heavy breathing during exercise has produced a carbon dioxide surplus in her muscles. lactate is being transported to her liver. this is a result of aerobic respiration. strenuous exercise has caused her body to be in carbon dioxide debt, and she is breathing hard while lactate is transported to the liver. this is a result of anaerobic respiration. strenuous exercise has caused her body to be in oxygen debt, and she is breathing hard while lactate is transported to the liver. this is a result of anaerobic respiration.

To take a whiff of your favorite food, you use both? a. motor nerves and your digestive system b. sensory nerves and your immune system c. motor nerves and your skeletal system d. sensory nerves and your respiratory system