1. Which one of the following does not have branchiae?
a. abalone
b. terrestrial snail
c. sea star
d. sea slug
e. clam

2. Which of the following features do all gas exchange systems have in common?
a. The exchange surfaces are moist.
b. They are enclosed within ribs.
c. They are maintained at a constant temperature.
d. They are exposed to air.
e. They are found only in animals.

3. Why is gas exchange more difficult for aquatic animals with gills than for terrestrial animals with lungs?
a. Water is denser than air.
b. Water contains much less O₂ than air per unit volume.
c. Gills have less surface area than lungs.
d. Only A and B are correct.
e. A, B, and C are correct.

4. Which of the following is an example of countercurrent exchange?
a. the flow of water across the gills of a fish and that of blood within those gills
b. the flow of blood in the dorsal vessel of an insect and that of air within its tracheae
c. the flow of air within the primary bronchi of a human and that of blood within the pulmonary veins
d. the flow of water across the skin of a frog and that of blood within the ventricle of its heart
e. the flow of fluid out of the arterial end of a capillary and that of fluid back into the venous end of the same capillary

5. Which one of the following statements about gills operating in water is false?
a. Water can support the delicate gill features.
b. Most fish actively pump water over their gills.
c. Keeping membranes moist is no problem.
d. Water carries more oxygen than air, and therefore gills need to be more efficient than lungs.
e. Gills have evolved many times in aquatic animals.

6. All of the following respiratory surfaces are associated with capillary beds except the
a. gills of fishes.
b. alveoli of lungs.
c. tracheae of insects.
d. skin of earthworms.
e. skin of frogs.

7. Air rushes into the lungs of humans during inhalation because
a. the rib muscles and diaphragm contract, increasing the lung volume.
b. pressure in the alveoli increases.
c. gas flows from a region of lower pressure to a region of higher pressure.
d. pulmonary muscles contract and pull on the outer surface of the lungs.
e. a positive respiratory pressure is created when the diaphragm relaxes.

8. You are studying a plant from the arid southwestern United States. Which of the following adaptations is least likely to have evolved in response to water shortages?
a. closing the stomata during the hottest time of the day
b. development of large leaf surfaces to absorb water
c. formation of a fibrous root system spread over a large area
d. mycorrhizae associated with the root system
e. a thick waxy cuticle on the epidermis

9. The photosynthetic cells in the interior of a leaf are what kind of cells?
a. parenchyma
b. collenchyma
c. sclerenchyma
d. phloem
e. endodermis

10. Gas exchange, necessary for photosynthesis, can occur most easily in which leaf tissue?
a. epidermis
b. palisade mesophyll
c. spongy mesophyll
d. vascular tissue
e. bundle sheath

11. A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are not being absorbed by this pigment?
a. red and yellow
b. blue and violet
c. green and yellow
d. blue, green, and red
e. green, blue, and violet

12. If photosynthesizing green algae are provided with H₂O synthesized with heavy oxygen (¹⁸O), later analysis will show that the ¹⁸O is in:
a. glucose
b. starch
c. O₂
d. CO₂
e. water

13. What are the products of the light reactions that are subsequently used by the Calvin cycle?
a. oxygen and carbon dioxide
b. carbon dioxide and ATP
c. water and carbon
d. electrons and photons
e. ATP and NADPH

14. Why is the respiratory system of a bird more efficient than the human respiratory system?
a. The bird respiratory system does not mix exhaled air with inhaled air.
b. A bird lung contains multiple alveoli, which increases the amount of surface area available for gas exchange.
c. The human respiratory system ends in small parabronchi, which reduce the amount of surface area available for gas exchange.
d. Only B and C are correct.
d. A, B, and C are correct.

15. The blood level of which gas is most important in controlling human respiration rate?
a. nitric acid
b. nitrogen
c. oxygen
d. carbon dioxide
e. carbon monoxide