Chapter 35

The most abundant gas in the atmosphere is ________. a. nitrogen c. oxygen b. carbon dioxide d. hydrogen

Respiratory pigments________. a. contain metal ions b. occur only in vertebrates c. increase the efficiency of oxygen transport d. both a and c

In crustaceans, most gas exchange occurs at ________. a. the tips of tracheal tubes b. the body surface c. \(g\) ills d. paired lungs

Countercurrent flow of water and blood increases the efficiency of gas exchange in ________. a. fish b. amphibians c. birds d. all of the above

In human lungs, gas exchange occurs at the ________. a. two bronchi b. pleural sacs c. alveolar sacs d. both b and \(c\)

When you breathe quietly, inhalation is ________and exhalation is________. a. passive; passive b. active; active c. passive; active d. active; passive

During inhalation ________. a. the thoracic cavity expands b. the diaphragm relaxes c. atmospheric pressure declines d. both a and c

Most oxygen in blood is transported ________. a. bound to hemoglobin b. as carbon dioxide \(c\) as bicarbonate d. dissolved in the plasma

Match the words with their descriptions. ________trachea ________pharynx ________alveolus ________hemoglobin ________bronchus ________bronchiole ________glottis ________diaphragm a. muscle of respiration b. gap between vocal cords c. fine branch of bronchiole tree d. windpipe e. respiratory pigment f. site of gas exchange g. airway leading to lung h. throat