Lab Quiz 5: 10/30/19

Before you gathered your raw data, you formulated a hypothesis about the expected results. After considering your data, do you accept or reject your hypothesis? Why?

Accept b/c the snails produced more carbon dioxide than the elodea

What are the advantages and disadvantages of anaerobic fermentation?

Advantages: Anaerobic respiration is relatively rapid, and it does not require oxygen. Disadvantages: Anaerobic respiration generates only two ATPs and produces lactic acid. Some of the lactic acid remains in the muscle fibers, where it contributes to muscle fatigue.

What is an aerobe? How does it differ from an anaerobe?

Aerobe: Organisms that use oxygen for respiration beyond glycolysis. Anaerobe: Live without oxygen and may even be killed by oxygen in the atmosphere. Many bacteria use nitrate, sulfate, or other inorganic compounds as the electron acceptor instead of oxygen.

How does the fate of Pyruvate differ between aerobic respiration and fermentation?

Aerobic respiration: Most organisms continue respiration by oxidizing pyruvate to CO2, via chemical reactions of the Krebs cycle. Fermentation: The pyruvate from glycolysis is reduced via anaerobic fermentation to either CO2 and ethanol or lactic acid.

What is your major conclusion from the results of this procedure?

Animals need more energy or ATP and will take in more oxygen to act as the final electron acceptor which will cause the release of more CO2.

In this exercise you measured the relative respiration rates of an animal and a plant. Why should you be cautious about having no algae in the control beaker?

Because the algae would have photosynthesized and taken up carbon dioxide and given a false reading of a lower respiration rate.

What is the summary equation for aerobic respiration?

C6H12O6 + 6 O2 ---> 6 CO2 + 6 H2O + ATP + Heat

What gas is responsible for the holes in baked bread?

CO2

Do you feel justified in drawing conclusions from your work about all plants and animals? Or only about snails and Elodea? Why?

I do not feel justified drawing conclusions about anything in this lab. I simply did one trial and observed 2 others. There are not enough solid trials to base any conclusions off of. There was not enough information on the objects used, their weight, their CO2 intake could not be measured precisely. There is not enough information or trials that could help me create a conclusion about this lab.

How would you expand this experiment to further test your conclusions about other plants and other animals?

In order to expand the experiment, I would add more plants and animals to test on. Aside from that, I would have more trials.

Why must aerobic organisms such as yourself inhale oxygen and exhale CO2?

Oxygen, the final electron acceptor in the electron transport chain, is reduced to form H2O. We breathe out the CO2 because it is a waste product of the oxidation of glucose.

How was the effect of the concentration of inhibitor tested in this experiment? How did the concentration of NaF affect anaerobic fermentation in your experiment? Why?

The effect of the inhibitor, NaF, was tested by measuring the difference in initial and final CO2 levels. With the addition of the inhibitor it restricted the production of the CO2 which decreased the rate of respiration because it is an inhibitor of glycolysis.

The organisms you will study include an animal (snail) and a plant (Elodea). Which do you think will respire more? Write your hypothesis here.

The snail will respire more

Why did tube 6 produce CO2 even though an inhibitor of glycolysis was present?

This is because there were more activators present in this tube than inhibitors. Tube 6 also included 2.5mL of Na pyruvate, which is an activator of respiration. Therefore, Na pyruvate counteracted the NaF inhibitor.

What features of the biology of the organisms that you used most likely contributed to the observed differences in respiration rate?

Titration of NaOH in this lab contributed to the differences in respiration rate

What was the purpose of tube 7?

Tube 7 was used as a control.

Why was more NaOH needed for Elodea?

Water amount did not change so CO2 increased. Because there is more CO2, there is more carbonic acid. Since there is more carbonic acid, more sodium hydroxide is needed to neutralize it.

What is the economic importance of fermentation by yeast?

Yeast is used by bakeries for bread, in alcohol, and wine.

Did magnesium (a cofactor that activates many enzymes) promote respiration? If not, what are some possible reasons?

Yes, it did

What is glucose?

a common organic molecule used as an energy source for respiration

Smell the contents of the tube containing the most CO2. What compound do you smell?

acetaldehyde

What is sodium fluoride (NaF)?

an inhibitor of some enzymes of glycolysis

List the specific location for each cellular process. Fermentation: Glycolysis: Kreb's Cycle: Electron Transport Chain:

cytoplasm cytoplasm mitochondrial matrix inner mitochondrial membrane

The Carbon in the CO2 produced by your metabolism comes from what molecule?

glucose

Which compounds listed in step 6 are intermediates in the respiratory pathway?

glucose and pyruvate

Compare tubes 4 & 5. How was CO2 production affected by the 10-fold increase in the amount of NaF? For example, was it changed 10-fold?

more CO2 There was more CO2 produced in the tube with less NaF.

What does cellular respiration involve?

oxidation of organic compounds and a concomitant release of energy

__________________ is the ultimate electron acceptor in the electron transport chain

oxygen

What is magnesium sulfate (MgSO4)?

provides Mg2+, a cofactor that activates some enzymes of glycolysis

Why did you subtract the control NaOH mL from the NaOH used in beakers 1 & 2?

to find the relative respiration rate of organisms

Organisms use the energy stored in ATP to do what?

work such as transport materials, reproduce, contract muscles, and remove wastes