Bios 1700 Exam 2

A simplified overall equation for respiration is as follows: C6H12O6 + 6O2 →6CO2+ 6H2O + energy In this reaction, we can say that _____ is reduced and _____ is oxidized.

oxygen; glucose

Which process produces the highest number of reduced electron carriers and thus the greatest potential for generating ATP?

the citric acid cycle

During the pyruvate oxidation stage of cellular respiration, which of the following occurs?

the formation of CO2 the oxidation of pyruvate the formation of acetyl-CoA the formation of NADH

Which is the only reaction in the citric acid cycle that produces ATP by substrate-level phosphorylation?

the formation of succinate

We can tell from their structure that fatty acids are a good source of energy because of:

the large number of carbon-carbon and carbon-hydrogen bonds they contain.

Of the 6 carbons in a starting molecule of glucose, at the completion of pyruvate oxidation, _____ carbons are fully oxidized to _____, while _____ carbons remain in _____.

two; CO2; four; acetyl groups

One of the enzymatic results of the pyruvate oxidation stage of cellular respiration is the reduction of _____ to _____.

NAD+; NADH

What product of the pyruvate oxidation stage of cellular respiration will have the two electrons that are lost from pyruvate?

NADH

Which of the following is an electron carrier in its reduced form?

NADH

When a single pyruvate is converted to acetyl-CoA during pyruvate oxidation, the other products of the reaction are:

NADH and CO2

The immediate source of electrons for the electron transport chain is:

NADH and FADH2

Researchers are studying a population of eukaryotic cells and notice that, regardless of the presence of ATP or ADP, the PFK-1 enzyme fails to function properly. Which of the following could be an explanation of this observation?

These cells may carry a mutation that alters the active site of the PFK-1 enzyme. These cells may carry a mutation that affects allosteric binding sites of the PFK-1 enzyme. These cells may carry a mutation that causes an overproduction of citrate.

Which statement is true regarding Earth's earliest organisms?

These organisms likely carried out fermentation and may have had rudimentary proton pumps.

In the citric acid cycle, after the acetyl-group (2C) from acetyl-CoA is transferred to oxaloacetate (4C) to produce citrate (6C), subsequent reactions eventually result in 4C intermediates that are rearranged to regenerate oxaloacetate. What happens to the other two carbons?

They are released as CO2 byproducts.

Energy released by transferring electrons along the electron transport chain is stored as potential energy in the form of:

a proton gradient

In which organisms would you expect ethanol fermentation to occur?

fungi and plants

In cellular respiration, oxygen:

gains electrons and is reduced

which of the following stages does not take place in the mitochondria?

glycolysis

Proteins can be broken down to extract energy. They are typically broken down into amino acids, which then enter cellular respiration via:

glycolysis or the citric acid cycle.

if you are a protein without a signal sequence, you will end up:

in the cytosol

Based on your interpretation of this model of phosphofructokinase-1 (PFK-1) activity, which of the following would increase PFK-1 activity?

increased concentration of AMP

Which of the following would most easily pass through the plasma membrane? a. oxygen (O2) b. glucose (monosaccharide) c. sodium ions (Na+) d. hydrogen ions (H+)

oxygen

In eukaryotes, fermentation takes place:

cytoplasm

Tracing the metabolism of one glucose molecule, how many carbon atoms are fully oxidized to CO2 at the completion of the pyruvate oxidation stage?

2

Once they have been processed through the citric acid cycle, the acetyl-CoA molecules from a single glucose molecule produce:

2 ATP, 6 NADH, 4 CO2, and 2 FADH2.

Which of the following is a net product of glycolysis?

2 pyruvate

Tracing the metabolism of one glucose molecule, how many carbon atoms are available for further oxidation at the completion of the pyruvate oxidation stage?

4

Which best describes energy captured in ATP during aerobic cellular respiration?

A small amount of energy is captured in ATP by substrate-level phosphorylation; most is captured in ATP by oxidative phosphorylation.

The enzyme phosphofructokinase-1 (PFK-1) is thought of as a metabolic "valve" that regulates the rate of glycolysis. Which of the following correctly identifies its allosteric activators and inhibitors and their actions?

ADP-activator; citrate-inhibitor

During the citric acid cycle:

ATP is synthesized by substrate-level phosphorylation.

The conversion of the potential energy of a proton gradient to a form more useful to the cell is achieved by coupling the movement of protons down their electrochemical gradient with the synthesis of ATP. This coupling is made possible by:

ATP synthase.

Each molecule of acetyl-CoA that enters the citric acid cycle carries two of the carbon atoms from the original starting glucose molecule. These carbon atoms will ultimately leave the citric acid cycle as carbon atoms in which of the following?

CO2

The ethanol resulting from fermentation of glucose only accounts for four of the six starting carbon atoms. In which of the following are the other two carbon atoms found?

CO2

Some bacteria run the citric acid cycle in reverse. Without any other modifications to the cycle, what inputs would be required to do this?

CO2, FADH2, NADH, and ATP

We consume a variety of carbohydrates that are digested into a variety of different monosaccharides. How do these different sugars enter glycolysis?

Different sugars can be modified to form different intermediates of glycolysis.

What happens when glucose is phosphorylated during phase 1 of glycolysis?

Glucose is destabilized so that it can be broken apart in phase 2.

which of the following is an example of an oxidized form of a molecule that is important in cellular respiration? a. NADH b. NAD+ c. FADH2

NAD+

Which statement is true regarding pyruvate and glucose?

Pyruvate can be transported across both membranes of the mitochondrion to be further metabolized, but glucose cannot.

Which statement is true regarding pyruvate oxidation?

Pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis.

if you are a protein that will be put outside of the cell through exocytosis, you will first travel through the:

Rough ER, Golgi Apparatus and Vesicle only

Lactic acid fermentation occurs in:

bacteria and animals

The majority of the energy captured in the citric acid cycle is in the form of:

electrons donated to NAD+ and FAD.

Most of the proteins of the electron transport chain are:

embedded in the inner mitochondrial membrane.

The citric acid cycle is believed to have developed fairly recently in the evolution of cellular life.

false

The majority of cells within the human body have a very high baseline amount of ATP, so cells are always prepared for any long-term activity.

false

Where does the F1 subunit of ATP synthase get its energy to catalyze the synthesis of ATP?

from rotational energy provided by the flow of protons through the channel in the Fo subunit

Pyruvate oxidation is an important stage in cellular respiration because:

it links glycolysis with the citric acid cycle.

On completion of either ethanol or lactic acid fermentation, the yield is only two ATP molecules per glucose molecule. The remaining chemical energy from the glucose is found primarily in:

lactic acid and ethanol

catabolism is a form of metabolism in which ______ molecules are converted into ________ molecules

large; small

During pyruvate oxidation, pyruvate is broken down into CO2 and an acetyl group. The CO2 is:

less energetic than the acetyl group.

a catalyst/enzyme works by:

lowering the activation energy

The chemical bonds of carbohydrates and lipids have high potential energy because:

many of these bonds are C—C and C—H bonds, in which electrons are shared equally between atoms.

In eukaryotes, pyruvate oxidation takes place in the:

mitochondrial matrix

The citric acid cycle takes place in the:

mitochondrial matrix

During the citric acid cycle, the production of CO2 is the result of the _____ of intermediate compounds of the citric acid cycle coupled to the production of _____.

oxidation; NADH

In cellular respiration, glucose is _____ to CO2 and oxygen is _____ to water.

oxidized; reduced

In cellular respiration, glucose is _____ to CO2 and oxygen is _____ to water. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices

oxidized; reduced

When an electron is transferred from NADH to CoQ, NADH is _____ and CoQ is _____.

oxidized; reduced

the energy that exists before baking soda and vinegar combine to crate carbon dioxide gas is:

potential energy

Acetyl-CoA synthesis occurs during:

pyruvate oxidation

When you exhale, there is more CO2 than was present in the air that you inhaled. This CO2 comes from reactions in:

pyruvate oxidation and the citric acid cycle.

During lactic acid fermentation, pyruvate is:

reduced

identify the process that requires energy in order to take place.

secondary active transport

Glucose is stored in plants as _____ and in animals as _____.

starch; glycogen

In glycolysis, ATP is synthesized by:

substrate-level phosphorylation

Coenzyme Q and cytochrome c:

transfer electrons between protein complexes of the electron transport chain.

Both NAD+ and molecular oxygen serve as electron acceptors in cellular respiration.

true

Conditions that reduce the strength of the proton gradient across the inner mitochondrial membrane slow the production of ATP by ATP synthase.

true

Although glycolysis produces four molecules of ATP by substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is because:

two molecules are used in the initial stage.

Which of the following is a product (as opposed to a substrate) of at least one of the processes of cellular respiration?

water