1) Consider a situation in which oxygen and carbon dioxide are mixed in a sealed

Question

1) Consider a situation in which oxygen and carbon dioxide are mixed in a sealed chamber at partial pressures of 350 mm Hg each. If a beaker of distilled, gas-free water is put into the chamber for several hours with this gas mixture until the system equilibrates, which of the following statements is correct? a. Because the partial pressures are the same, the amount of each gas dissolved in the water will be the same. b. There will be more oxygen in solution than carbon dioxide, because oxygen is more soluble in water. c. There will be more carbon dioxide in solution than oxygen, because carbon dioxide is more soluble in water. d. There will be more carbon dioxide than oxygen in the gas phase 2)Which of the following is a difference between gas exchange in mammals and birds? a. Mammals exchange gases using a countercurrent arrangement of capillaries in the lungs whereas birds use crosscurrent exchange b. Mammals are homeotherms, but birds are not c. Bird lungs have a large surface area, while those of mammals do not. d. Air travels bidirectionally through the lungs of mammals, but unidirectionally in birds 3)Assume that at a partial pressure of 100 mm Hg of oxygen in the lungs, as typically found at sea level, oxygen will dissolve into blood to a concentration of roughly 0.1 mM. If you climb a mountain to 6000 meters above sea level, the partial pressure of oxygen in the lungs decreases to 50 mm of Hg. According to Henry’s Law, what would the concentration of oxygen in blood be at this elevation? a. 0 mM b. 0.05 mM c. 0.1 mM d. 0.2 mM 4)Hemoglobin respiratory pigment molecules a. are found in nearly all vertebrates and most annelids (segmented worms) because this extremely useful molecule evolved in a common ancestor of vertebrates and annelids and was retained in descendant lineages because it was strongly favored by natural selection b. in mammals can bind up to two oxygen molecules per hemoglobin molecule c. in vertebrates typically show a higher affinity for oxygen when blood pH is lower d. in vertebrates typically release more oxygen for each unit drop in oxygen partial pressure in the blood when the partial pressure is low than when it is high 5)Symptoms of decompression sickness are more likely to occur if a scuba diver a. returns to the surface very slowly, resting during the ascent b. breathes a mixture with less nitrogen in the mix c. breathes pressurized air d. all of the above 6)At sea level, at a pressure of 1 Atm (= 760 mm Hg), O2 comprises ~21% of all air molecules. At 7,500 m above sea level, atmospheric pressure is 0.4 Atm and O2 comprises a. ~84% of air by weight b. ~42% of all air molecules c.~21% of all air molecules d. ~8% of all air molecules 7)Which of the following statements is/are true about the basic structure of the circulatory systems in question? a. Mammals and birds give their blood a single pump to send it through both the systemic circuit and the respiratory circuit b. Fish give their blood one pump to send it through the systemic circuit and another pump to send it through the respiratory circuit c. Cephalopods give their blood one pump to send it through the systemic circuit and another pump to send it through the respiratory circuit d. All of the above are true 8)Which of the following is true of avian respiratory systems? a.As in most other terrestrial vertebrates, oxygen-rich and oxygen-poor air mix as birds inhale and exhale, reducing the partial pressure of the air in the air capillaries in the parabronchi b.When birds exhale, both anterior and posterior air sacs expand c.When birds exhale, oxygen-poor air moves out of the anterior air sacs and anterior portion of the parabronchi and is exhaled, while oxygen-rich air from the posterior air sacs moves mainly into the posterior secondary bronchi and parabronchi d.When birds inhale, oxygen-poor air moves from the anterior air sacs and anterior portion of the parabronchi to the posterior air sacs, while oxygen-rich air from the posterior air sacs moves mainly into the anterior secondary bronchi 9)The tracheal system typically found in insects & most spiders a. reduces or eliminates the need for bulk flow for moving oxygen & carbon dioxide through the bodies of small insects b. works in part because oxygen diffuses through air dramatically faster than through water c. provides an “all air” path from the air outside the body to the vicinity of each cell d).All of the above are true 10)Insect “breathing” a. always involves only diffusion b. can involve both diffusion and some bulk flow (convection or ventilation) c. involves the entry and exit of gases through openings in the exoskeleton (spiracles) that are so tiny that no water vapor can pass through them, an adaptation that avoids any problems with water loss d. is regulated mainly by oxygen partial pressure (as in mammals) SHORT ANSWER 1)How does Fick’s second law of diffusion t = x2 explain why circulatory systems are necessary for large animals (and especially for those with high metabolic rates)? 2)With respect to maximizing the rate of diffusion, and keeping in mind the equation describing diffusion rate (based on Fick’s first law of diffusion) , , briefly describe three examples of adaptations/strategies that are commonly seen in organisms (one each related to A, delta C, and delta x) that result in an increased rate of diffusion and explain why each would increase diffusion rate. 3)Briefly explain why is it dangerous to fly in an airplane shortly after scuba diving. 4)If nitrogen gas is 78% of air by volume, total air pressure is 760 mm Hg = 1 Atm at sea level, and pressure increases in the ocean by ~1 Atm with each additional 10 m below sea level, what is the partial pressure of nitrogen gas in a volume of air brought down from sea level to 30 m below sea level? Show your work. Comparing different possible flow arrangements with respect to diffusive gas exchange: a) Draw a diagram illustrating how concurrent and countercurrent flow arrangements in a fluid medium-blood exchange membrane differ in their efficiency b) Explain (using words and/or formula) why one of these is more efficient than the other. c) Describe how a crosscurrent flow arrangement is similar to and different from crosscurrent and countercurrent flow and how and why the efficiency of crosscurrent flow differs from concurrent and countercurrent flow d) Give three real-world examples of countercurrent flow arrangements we discussed in class and one example of crosscurrent exchange

Explanation / Answer

1. The correct answer is option B. Because oxygen have high percentage (13.7%) in air and oxygen is more soluble in water. A gas always move from the higher partial pressure to lower pressure.

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