Fred loves La Paz, Bolivia so much that he decides to stay there for a couple years. All of the following changes could be considered a compensatory mechanism in response to the chronically decreased oxygen content EXCEPT a. an increase in amount of circulating red blood cells.
b. an increase in oxygen extraction by perfused cells.
c. an increase in hemoglobin’s affinity for oxygen.
d. a decrease in heart rate.

d. a decrease in heart rate.

Explanation:

As the altitude rises, the number of oxygen molecules in the air decreases. Lower oxygen levels at high altitudes stimulate the release of erythropoietin (EPO), which is associated with the increased red blood cells, i.e., it enables more oxygen molecules to be transported to cells and tissues. Moreover, at high latitudes, the increased hemoglobin (Hb)–oxygen affinity helps to safeguard arterial O2 saturation and thus mitigates the effects of low oxygen concentration in arterial blood (arterial hypoxemia). Finally, oxygen extraction depends on an appropriate supply of oxygen in the blood vessels. An increased oxygen extraction occurs when there is an inadequate circulating blood volume or when the number of red blood cells decreases below the normal levels.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."    

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.