Biology 11A Chapter 7 - Post Lab Review

Fermentation and Temperature Graph Respirometers were set up that contained yeast and 2% glucose solution. Each respirometer was placed at a different temperature. The height of the bubble contained in the respirometer was measured every 5 minutes for 20 minutes. The results can be seen in the graph below. Which of the tested temperatures is optimum for yeast fermentation

37 degrees Celsius Explanation: The respirometer bubble height measures the amount of carbon dioxide produced during fermentation. The tubes that was placed at a temperature of 37 degrees Celsius shows the greatest amount of Carbon Dioxide production, this it had the greatest amount of yeast fermentation.

Respirometer Volume calculation Tube C contained non-germinating seeds. If the initial measurement for this tube was 82mm, what was the final measurement?

76mL Explanation: If Tube C saw a change of about 6 mL and it originally measured at 82 mL then the final measurement would have been 82mL - 6mL = 76mL

Nongerminating soybeans During the soybean experiment the nongerminating soybeans consumed around 0.02 mL/min of oxygen. What does this tell you about the cellular respiration of the nongerminating soybeans.

A little cellular respiration was taking place but not enough for growth

Gas production in fermentation In the yeast fermentation experiment, what is being produced to cause the air bubble at the top of the tube to increase over time?

Carbon Dioxide Explanation: Carbon dioxide is released as result of the fermentation reactions

Why measure Oxygen? When trying to determine the rate of cellular respiration (an aerobic process), why is the oxygen measured and not carbon dioxide?

Carbon Dioxide is produced during both aerobic and anaerobic processes; we couldn't be sure cellular respiration was taking place Explanation: Because carbon dioxide is produced during both anaerobic and aerobic processes within the cell, we couldn't be sure that the aerobic process was occurring and so we couldn't be sure we were measuring the rate of the cellular respiration

Monosaccharide use for fermentation Glucose and fructose are both monosaccharides. During the yeast fermentation lab, why did glucose show a higher rate of fermentation than fructose?

Fructose had to be converted into glucose before the yeast could use it for fermentation Explanation: Yeast can only use glucose for the process of fermentation which means fructose had to be converted to glucose before it could be used. This slowed down the rate at which it could be used by the yeast.

In cellular respiration, carbon dioxide is formed from the oxidation of which of the following?

Glucose Explanation: NADH also undergoes oxidation but in order to form carbon dioxide, the molecule oxidized must contain carbon, as in glucose

A student set up respirometers to measure fermentation of two different carbohydrates by yeast. He measured the height of the bubble (in mm) in each respirometer every 5 minutes for 2- minutes. His data can be seen in the table below. Time (minutes) Tube A Tube B 0 4 4 5 4 4 10 4 4 15 4 4 20 4 4 Which of the errors listed below could have caused him to get this result?

He forgot to add the yeast

Yeast fermentation Which of the following does NOT occur during yeast fermentation?

Lactate is produced

Muscle cells and fermentation In muscle cells, fermentation produces not alcohol but

Lactic acid

Yeast cells under anaerobic conditions

Produce ethyl alcohol (ethanol)

Results of movement of the bubble in respirometer What information did the movement of the bubble over a specified distance in the calibrated respirometer provide? (check all that apply)

The amount of potassium hydroxide used The rate of cellular respiration the volume of oxygen used the volume of carbon dioxide used The amount of time for the reaction to complete Explanation: The movement of the bubble within the respirometer provided a means to measure the amount of oxygen that was being consumed by the seeds as they went through cellular respiration. The KOH was used to absorb any carbon dioxide formed thus the volume of air in the tube became less and less as the oxygen was consumed

Reaction rate of yeast suspension What would you predict would happen to the fermentation rate if you used yeast suspension that had not been swirled/mixed each time before it was dispensed into test tubes?

The reaction rate would be very low Explanation: Since the yeast quickly settle to the bottom of the suspension, if the yeast suspension is not swirled each time it is used, mainly water would be poured from the suspension

Using the respirometer, how can you determine which carbohydrate is used most efficiently by yeast for fermentation?

The solution in the tube with the largest gas bubble has fermented most efficiently

Germinating soybeans will have a higher cellular respiration rate than non-germinating soybeans?

True

Respirometer ID A cotton ball with 15% potassium hydroxide, which absorbs excess carbon dioxide, was added to three different test tubes. On top of the cotton ball, an equal weight of either glass beads, germinating seeds, or non-germinating seeds was placed. A respirometer was attached to the top of each test tube and the volume was measured every 5 minutes for 30 minutes. The change in volume for each of the three tubes can be seen in the graph below. Which of the tubes is most likely to have contained the germinating seeds?

Tube B Or Tube with the highest change in respirometer Explanation: Tube B saw the greatest amount of change in volume, this it must have had the seeds that were growing (germinating) and thus needed more energy. To create more energy the seeds used more oxygen than the other two tubes.

Yeast are able to ferment a variety of sugars in anaerobic conditions. Carbon dioxide is produced as a byproduct. A respirometer can be used to determine how much carbon dioxide is produced and this measure rates of fermentation. Respirometers were set up that contained yeast and either a solution containing a carbohydrate or distilled water. The height of the bubble contained in the respirometer was measured every 5 minutes for 20 minutes. The results can be seen in the graph below. Which of the respirometers is the most likely to contain distilled water and yeast? Which of the respirometers contains the carbohydrate that is fermented most efficiently by the yeast?

Tube E (Lowest value line) Tube A (Highest Value line) Explanation: There is no change seen in Tube E, which means no carbon dioxide was produced; this tells us that there must have been no sugar for the yeast to use in fermentation. Tube A, on the other hand, had the greatest amount of carbon dioxide produced which means the carbohydrate in this tube was utilized the most efficiently to allow for the greatest rate of fermentation

Conditions of fermentation Under what environmental conditions do yeast carry out fermentation?

absence of oxygen

Which type of process is alcoholic fermentation?

anaerobic

How should the gas bubble should be read?

by the leading edge

How is a respirometer used to measure fermentaiton

by the size of the gas bubble produced

Which gas is produced as a result of fermentation?

carbon dioxide

Which gas is produced by cell respiration?

carbon dioxide

Soybean use of oxygen and ATP In the soybean experiment, the (_____) used more oxygen and the (_____) used more ATP

germinating seeds germinating seeds

Processes that will occur in the presence or absence of oxygen Which of the following processes will occur in the presence or absence of oxygen?

glycolysis

Which is incorrect about fermentation?

it generates oxygen

Muscles functioning anaerobically Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for the buildup of which molecule?

lactate Explanation: In anaerobic conditions, pyruvate does not enter the Krebs cycle, but rather is converted into lactate during fermentation. Once muscles run out of oxygen, the lactate production would increase, and the sports physiologists would be able to measure this increase in the athlete's blood

Device used to measure the rate of gas exchange A device that can be used to measure the rate of exchange of oxygen and carbon dioxide during energy-acquiring pathways is called a

respirometer

Respirometers were set up that contained yeast and 2% glucose solution. Each respirometer was placed at a different temperature. The height of the bubble contained in the respirometer was measured every 5 minutes for 20 minutes. What is the independent variable in this experiment?

temperature

Highest respiration rate in germinating or non-germinating soybeans During the experiment measuring energy production in plants, the highest rate of cellular respiration occurred in

the tube containing germinating seeds