Feedback Pre-Assessment

The graph models core body temp during rapid changes in the environment.

Which statement explains the pattern in the graph?

• Vasodilation and vasoconstriction trigger an immediate increase in body temp

• Vasodilation and vasoconstriction are dependent on the time of day

• Body temp is controlled by an internal feedback mechanism

• Body temp varies in a predictable pattern during the day

When the level of CO2 in the blood is too high, the excess CO2 reacts with water and produces carbonic acid. The carbonic acid causes the blood pH to become more acidic. When the blood pH becomes too acidic, chemoreceptors in the brain instruct the body to react and maintain homeostasis in blood pH.

Which of these responses by the body would eliminate the excess CO2 and help maintain homeostasis?

• Decreasing the heart rate

• Breathing more deeply and frequently

• Increasing glucose levels in the blood

• Increasing body temp by shivering

If a person has a blood-calcium (Ca2+) level of 8 mg/100mL of blood, which of the following mechanisms does the body use to maintain blood-calcium homeostasis?

• The kidneys take up more Ca2+ and release vitamin D

• The bones release Ca2+

• The intestines increase reabsorption of Ca2+

• All of the above

The osmoregulation process is an example of?

• Disruption of homeostasis by exercise

• Maintenance of homeostasis by a feedback mechanism

• Control of urine production by the parasympathetic nervous system

• The role of the endocrine system in increasing oxygen content of red blood cells

A dog's pituitary gland produces the hormone ACTH, which stimulates the adrenal glands to secrete cortisol. Cortisol helps regulate body weight, mineral balance, the structure of connective tissue, the production of white blood cells, and skin health. When cortisol levels are low, the pituitary gland secretes ACTH. When cortisol levels are high, the pituitary gland stops secreting ACTH. Based on this information, which of the following would most likely be the cause of elevated levels of cortisol in a dog?

• An immune response to the excess level of cortisol

• An inactive pituitary gland

• An excess of ACTH

• Undersized adrenal glands

Changes in water pressure within guard cells cause the cells to open or close the stomata. This response helps the plant maintain homeostasis by-

• stabilizing the plant's temperature through the evaporation of water

• regulating the amount of water the plant loses during transpiration

• allowing oxygen needed for photosynthesis to enter the plant

• enabling the plant to release more carbon dioxide at night for photosynthesis