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What is the main function of respiration in living organisms?
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The release of energy. It is the process of converting chemical energy of organic molecules to another form of chemical energy (ATP) which is used by the organism for various processes.
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If cells respire in a closed air chamber, should the pressure of the chamber change?
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No because the increase in atmospheric pressure due to the release of carbon dioxide should exactly equal the decrease in pressure due to the consumption of oxygen.
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What is the result of adding an alkaline solution into a closed air chamber where a cell is doing respiration?
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The alkaline solution removes all of the carbon dioxide produced and converts it to a salt and therefore the pressure of the chamber will decrease due to the consumption of the oxygen.
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What happens if a dilute acid is present in a closed air chamber where a cell is doing respiration?
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There will be no net change in the gas pressure since O2, N2 and CO2 are only sparingly soluble in a dilute acid.
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What is a respirometer?
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A chamber where experiments on cell respiration where the change in gas pressure is measured in order to measure cellular respiration.
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What was the thermobarometer we used in the pea respirometer experiment?
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A test tube that only contained water and no peas and was used to measure factors that were independent of respiration such as the changes in room temperature and pressure.
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What is a respiratory quotient?
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A respiratory quotient is the the ratio of carbon dioxide released in cellular respiration over the carbon dioxide consumed.
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When will the respiratory quotient not be equal to 1?
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If the respiratory substrate (substance that is respired) is not glucose and/or if anaerobic respiration is also taking place.
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Why did we expect to find a respiratory quotient that is less than 1 in the pea experiment.
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Because since peas are not only made of carbs (sugar), the respiratory substrate was not only sugar. Peas also contain fats and proteins which have respiratory quotients of less than 1.
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Safety in this lab.
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Do not inhale NaOH or sulphuric acid or sodium fluoride.
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Why is yeast used in the study of respiration?
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It is easily handled and can respire many carbohydrates and their derivatives by aerobic respiration or fermentation and because the metabolic pathway is very similar to those of plants and animals.
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True or false. Yeast cells often use aerobic and anaerobic respiration if oxygen is available.
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True.
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Why is Mg++ essential in the respiratory pathway?
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Mg++ is used as a cofactor to the enzyme dehydrogenase which is used as a necessary catalyst.
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Why are high concentration of F- poisonous to living cells?
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The F- combines with the Mg++ and forms an insoluble salt. The Mg++ is no longer available to act as a cofactor to the catalyst dehydrogenase and therefore any reaction beyond the ones that require Mg cease. The result is that the CO2 output for these intermediates is inhibited.
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In the fermentation experiment, why didn't the test tube containing galactose have a change in pressure?
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There was no enzyme added to the test tube to convert galactose to glucose and fermentation only occurs with glucose.
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