L15_Act_1106S23

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1106

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Jan 9, 2024

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BIOL 1106 Activity Spring 2023 Lesson 15: Gas Exchange in Multi-celled Animals (10 pts) This graded assignment is subject to the Virginia Tech Honor Code. Sharing or posting any content from this assignment, or using such shared or posted assignment content to answer assignment questions, is a violation of the Virginia Tech Honor Code. Names and email addresses of team members: 1. 2. 3. Learning Objectives: 1. Provide examples of evolutionary strategies that have maximized gas diffusion in invertebrate and vertebrate respiratory systems. 3. Explain the roles of counter current flow, diffusion, and partial pressures in gas exchange. 5. Using the oxyhemoglobin dissociation curve, explain how hemoglobin provides an oxygen reserve. 6. Explain the benefits of an oxygen reserve and how myoglobin also contributes to the reserve. S1: Apply scientific reasoning to biological problems. S3: Interpret and draw conclusions from scientific data S4: Apply basic quantitative methods to biological problems Part I: Fick’s Law in Plain English (LO 1, 3). Everyone has the capacity to understand Fick’s Law, but textbooks don’t always do a great job of making it understandable. This part of the activity will guide you to construct an understanding of Fick’s law to explain concepts of diffusion in respiration. Your textbook (Raven et. al 2011, p. 1002) says: Fick’s Law states that for a dissolved gas, the rate of diffusion ( R ) is directly proportional to the pressure difference (Δ p ) between the two sides of the membrane and the area ( A ) over which the diffusion occurs. Furthermore, R is inversely proportional to the distance ( d ) across which the diffusion must occur. A molecule-specific diffusion constant, D , accounts for the size of the molecule, membrane permeability, and temperature. Shown as a formula, Fick’s Law is stated as: R = DAΔp d This graded assignment is subject to the Virginia Tech Honor Code. Sharing or posting any content from this assignment, or using such shared or posted assignment content to answer assignment questions, is a violation of the Virginia Tech Honor Code. 1
BIOL 1106 Activity Spring 2023 1. (2 pts) Many people would find this explanation difficult to understand. Explain Fick’s Law in plain English. To do this, describe how each of the variables relates to the rate of diffusion ( R ). For example, you can say something like “When the pressure difference on two sides of a membrane is high, the rate of diffusion is also high.” Type your explanation in the box below: 2. (1 pt) Our lungs are not like big air-filled balloons inside our chests. Instead, they are packed with millions of alveoli, so lungs are more like big balloons filled with millions of tiny balloons. Which variable of Fick’s Law is maximized by having alveoli instead of big, balloon-like sacs? In one sentence, how does emphysema affect the diffusion of gases in and out of the lung, based on Fick’s Law? Part II: Partial Pressure and Gas Exchange (LO 3) Gas exchange in the lungs and in peripheral tissues depends on differences in partial pressure. For each of the following, describe in one sentence the gradient of partial pressure that drives gas exchange and the direction of gas movement under normal conditions at sea level. (0.5 pt each) a. Exchange of O 2 in the lungs: b. Exchange of CO 2 in the lungs: c. Exchange of O 2 in peripheral tissue: d. Exchange of CO 2 in peripheral tissue Part III: Understanding oxyhemoglobin dissociation curves (LO 5 & 6). This graded assignment is subject to the Virginia Tech Honor Code. Sharing or posting any content from this assignment, or using such shared or posted assignment content to answer assignment questions, is a violation of the Virginia Tech Honor Code. 2
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