נשימה תאית
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Q1: How do microrespirometers measure cellular respiration in germinating seeds?
Microrespirometers measure cellular respiration by tracking oxygen consumption. As germinating seeds consume oxygen for energy, carbon dioxide is released and absorbed by potassium carbonate. This reduces the overall gaseous pressure inside the sealed chamber, causing manometer fluid to move up the capillary tube. The distance traveled indicates the rate of oxygen consumption and cellular respiration.
Q2: Why is potassium carbonate used in the microrespirometer setup?
Potassium carbonate absorbs the carbon dioxide released by germinating seeds during cellular respiration. By removing CO2 from the chamber, only oxygen consumption affects the gas pressure inside the microrespirometer. This allows the manometer fluid movement to accurately reflect the rate of oxygen uptake and respiration activity.
Q3: What is the purpose of using glass beads as a control in this experiment?
Glass beads serve as a control because they do not undergo cellular respiration. By comparing manometer fluid movement in beads versus germinating seeds, researchers can isolate the respiration signal from other physical or chemical changes. Any pressure changes in the bead control indicate experimental error rather than biological activity.
Q4: How does temperature affect the respiration rate of germinating seeds?
The experiment tests whether higher temperatures increase respiration rates in germinating seeds. Seeds placed in heated water baths are compared to those at room temperature. If respiration rate increases with temperature, the manometer fluid in heated microrespirometers will travel farther in the same time period than in room temperature controls.
Q5: What does the slope calculation represent in the respiration data analysis?
The slope represents the rate of cellular respiration over time. It is calculated by dividing the distance the manometer fluid traveled by the time elapsed. A steeper slope indicates faster oxygen consumption and higher respiration rates, allowing comparison between experimental conditions and controls.
Q6: Why must the microrespirometer chambers remain undisturbed after sealing?
Once sealed with manometer fluid, the microrespirometer creates a closed system where pressure changes directly reflect oxygen consumption. Disturbing the chamber—bumping the table or inserting objects—introduces physical pressure changes unrelated to respiration. This would produce inaccurate measurements and invalidate the experimental results.
Q7: How is the bar graph used to compare respiration rates across experimental groups?
The bar graph plots respiration rates calculated from slope values for each microrespirometer group: control room temperature, control heated, experimental room temperature, and experimental heated. Visual comparison of bar heights reveals differences in respiration between seeds and beads, and shows the effect of temperature on respiration rates.