1. What are animals with hydrostatic skeletons able to do that animals with exoskeletons or internal skeletons cannot do?
a. elongate
b. crawl
c. live in aquatic environments
d. grow without replacing their skeleton
e. A, B, and D

2. What is the support structure of the land snail?
a. hydrostatic
b. chiton
c. bone
d. chondroitin
e. shell

3. The secretion of hormone A causes a change in the amount of protein X in an organism. If this mechanism works by positive feedback, which of the following statements represents that fact?
a. An increase in A produces an increase in X.
b. An increase in X produces a decrease in A.
c. A decrease in A produces an increase in X.
d. A and B are correct.
e. B and C are correct.

4. Which of the following is (are) true?
a.Hormones regulate cellular functions, and negative feedback regulates hormone levels.
b. The circulating level of a hormone is held constant through a series of positive feedback loops.
c. Both lipid-soluble hormones and water-soluble hormones bind to intracellular protein receptors.
d. Only A and D are true.
e. A, B, and C are true.

5. What do nitric oxide and epinephrine have in common?
a. They both function as neurotransmitters.
b. They both function as hormones.
c. They are both involved in the "fight-or-flight" response.
d. Only A and B are correct.
e. A, B, and C are correct.

6. Substance X is secreted by one cell, travels a short distance through interstitial fluid, and produces an effect in a cell immediately adjacent to the original secreting cell. All of the following terms could describe this substance except
a. nitric oxide.
b. neurotransmitter.
c. prostaglandin.
d. pheromone.
e. growth factor.

7. What is the mode of action of aspirin and ibuprofen?
a. They inhibit the synthesis of prostaglandins.
b. They inhibit the release of nitric oxide, a potent vasodilator.
c. They block paracrine signaling pathways.
d. They stimulate the release of oxytocin.
e. They stimulate the release of endorphins.

8. A cell that contains proteins enabling a hormone to selectively bind to its plasma membrane is called a(n)
a. secretory cell.
b. plasma cell.
c. endocrine cell.
d. target cell.
e. regulatory cell.

9. Iodine is added to commercially-prepared table salt to help prevent deficiencies of this essential mineral. Which gland(s) require(s) iodine to function properly?
a. parathyroids
b. adrenal
c. thyroid
d. pancreas
e. ovaries and testes

10. Blood samples taken from an individual who had been fasting for 24 hours would have which of the following?
a. high levels of insulin
b. high levels of glucagon
c. low levels of insulin
d. low levels of glucagon
e. both B and C

11. The star of a recent movie was a caterpillar that never matured into an adult. It simply got larger with each molt. What is the probable reason why the caterpillar did not mature into an adult?
a. lack of ecdysone
b. lack of juvenile hormone
c. decreased level of ecdysone
d. increased level of juvenile hormone
e. lack of the melatonin hormone

12. We know from the experiments of the past that plants bend toward light because
a. they need sunlight energy for photosynthesis.
b. the sun stimulates stem growth.
c. cell expansion is greater on the dark side of the stem.
d. auxin is inactive on the dark side of the stem.
e. phytochrome stimulates florigen production.

13. A botanist exposed two groups of the same plant species to two photoperiods-one with 14 hours of light and 10 hours of dark and the other with 10 hours of light and 14 hours of dark. Under the first set of conditions, the plants flowered, but they failed to flower under the second set of conditions. Which of the following conclusions would be consistent with these results?
a. The critical night length is 14 hours.
b. The plants are short-day plants.
c. The critical day length is 10 hours.
d. The plants can convert phytochrome to florigen.
e. The plants flower in the spring.

14. The steroid hormone that triggers molting in arthropods is
a. ecdysone
b. glucagon
c. thyroxine
d. oxytocin
e. growth hormone

15. If you were shipping green bananas to a supermarket thousands of miles away, which of the following chemicals would you want to eliminate from the plants' environment?
a. CO₂
b. cytokinins
c. ethylene
d. auxin
e. gibberellic acids