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73 terms

Micro Test 2 ( Mastering)

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Where would you expect to find electron transport chains in a prokaryote?
plasma membrane
According to the animation, which compounds provide electrons to the system?
NADH and FADH2
In the electron transport chain?
Oxygen is the terminal electron acceptor, the last molecule to receive the electrons from the system.
According to the animation, what does oxygen get reduced to at the end of the electron transport chain?
Water
According to the animation, what does the electron transport chain do to the concentration of hydrogen ions (protons)?
The concentration of protons is higher outside the membrane than inside.
The process of generating ATP using a proton gradient is referred to as
chemiosmosis.
Why does FADH2 yield less ATP than NADH?
FADH2 electrons enter the electron transport chain at a lower energy level.
Which of the following can be used as a final electron acceptor for aerobic respiration?
Molecular oxygen
What is one difference between ubiquinones and cytochromes?
Ubiquinones are not made of protein; cytochromes are.
How does the proton gradient help ATP synthase to make ATP?
Protons move from outside the membrane to inside the membrane.
Iron is considered an essential element for many bacteria. Based on the animation, how would lack of iron affect energy production of a bacterium?
Lack of iron would mean lack of heme, and thus lower amounts of functioning cytochrome proteins. This would mean lower energy yields.
Which of the following statements about fermentation is true?
It is an alternative way to return electron carriers to their oxidized state.
What is the role of pyruvic acid in fermentation?
It takes the electrons from NADH, oxidizing it back into NAD+.
What is the fate of the NAD+ newly regenerated by fermentation?
It returns to glycolysis to pick up more electrons.
Which of the following is an acid produced by fermentation?
Lactic acid and propionic acid
Cellular respiration uses ________ as the final electron acceptor
Oxygen
What is the intermediate product formed by pyruvic acid during alcoholic fermentation?
Acetaldehyde
Why is ATP required for glycolysis?
ATP makes it easier to break apart glucose into two three-carbon molecules.
Glycolysis literally means
sugar splitting.

(breaking apart sugar)
How many net ATPs can be made from one molecule of glucose in glycolysis?
Two
What carbon molecules remain at the end of glycolysis?
Pyruvic acid
Which of the following statements about glycolysis is true?
Glycolysis is also called the Embden-Meyerhof pathway.
Glycolysis produces energy in which form?
NADH and ATP
Which step is the step for which glycolysis is named?
Fourth
What is meant by substrate-level phosphorylation?
Production of ATP by transferring phosphates directly from metabolic products to ADP
What is the driving force of energy production in steps 6 and 7?
The oxidation of three-carbon compounds
What is the net production of ATP in glycolysis?
Two ATP
What occurs at the bridge step?
Decarboxylation of pyruvic acid
Based on the animation, how many electron carriers are reduced in the Krebs cycle only?
Four
What is the function of GTP?
An energy carrier
What is the fate of metabolites during respiration?
They are oxidized completely to carbon dioxide and water.
Which of the following is needed as a reactant for the first step of the citric acid cycle?
Oxaloacetic acid
Where does the energy come from to power the formation of GTP?
Succinyl CoA
Which step involves the release of carbon dioxide?
The third and fourth steps
How many molecules of ATP can be generated from one molecule of NADH?
Three
Which step(s) of the Krebs cycle does (do) not produce any usable energy?
The second and seventh steps
Fermentation.....
In fermentation, energy is released from sugars or organic molecules, such as amino acids, organic acids, purines and pyrimidines.

Fermentation produces only small amounts of ATP (one or two ATP molecules for each molecule of starting material).

Fermentation does not require oxygen, but sometimes can occur in the presence of oxygen.
During glycolysis:
NAD+ is reduced to NADH, and there is a net production of 2 ATP molecules by substrate-level phosphorylation.
Which of the following statements regarding the chemiosmotic mechanism of ATP generation is false?
In eukaryotic cells, the outer mitochondrial membrane contains the electron transport carriers and ATP synthase; whereas, in most prokaryotic cells, they are located in the plasma membrane.
The following are TRUE in ATP generation:
Proton pumps occur as some of the carriers in the electron transport chain (ETC) actively transport protons across the membrane.

The phospholipid membrane is normally impermeable to protons, so this unidirectional pumping establishes a proton gradient.

Within the inner mitochondrial membrane, the carriers of the electron transport chain (ETC) are arranged into three complexes.
Which of the following is the correct sequence of events that occur during the energy-conserving stage of glycolysis?
1 - An enzyme relocates a phosphate group of 3-phosphoglyceric acid to form 2-phosphoglyceric acid.
2 - Glyceraldehyde-3-phosphate is converted to 1,3 diphosphoglyceric acid.
3 - A high-energy phosphate is transferred from phosphoenolpyruvic acid to ADP, forming ATP.
4 - By the loss of a water molecule, 2-phosphoglyceric acid is converted to another molecule, upgrading the phosphate bond to a high-energy bond.
5 - A high-energy phosphate is moved to ADP, forming ATP, which is the first net ATP production of glycolysis.
2,5,1,4,3
The respiration of glucose (cellular respiration) typically involves which three principal stages?
Glycolysis, Krebs cycle, and the electron transport chain
Before amino acids (the building blocks of proteins) can be catabolized, they must be converted to other substances that can enter the Krebs cycle by all of the following methods, except:
transamination.
Which of the following nutritional classes of organisms use carbon dioxide (CO2) as their carbon source and use light as their energy source?
Photoautotrophs
Nitrobacter bacteria use carbon dioxide () for their carbon source and nitrate ions as an energy source. This organism is a ________.
chemoautotroph
If two-carbon fragments of acetyl CoA are successively linked to each other via dehydration synthesis reactions, what biosynthetic pathway is likely involved?
Lipid biosynthesis
Lipases break down
lipids
The Pentose Phosphate Pathway
is an example of anabolism.
According to the animation, oxidative phosphorylation
is a catabolic process.
According to the animation, the reactions that occur between glucose and pyruvic acid
can either be anabolic or catabolic.
Which of the following terms refers to pathways that can function both in anabolism and catabolism?
Amphibolic pathways
Which of the following statements about anaerobic respiration is false?
It involves glycolysis only.
What is the fate of pyruvic acid in an organism that uses aerobic respiration?
It is oxidized in the Krebs cycle.
A strictly fermentative bacterium produces energy
By glycolysis only.
The advantage of the pentose phosphate pathway is that it produces all of the following EXCEPT
Three ATPs.
Which of the following statements about beta oxidation is false?
It is a step in glycolysis.
Which of the following is the best definition of fermentation?
The oxidation of glucose with organic molecules serving as electron acceptors
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.
glycolysis → acetyl CoA → citric acid cycle → electron transport chain

Glycolysis produces pyruvic acid, which enters the mitochondrion. There, it is converted to acetyl CoA, which enters the citric acid cycle. Electron carriers bring electrons from the first three steps to the electron transport chain, and ATP is made.
What is the correct general equation for cellular respiration?
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy

Cellular respiration extracts energy from glucose (C6H12O6) to produce smaller energy packets (ATP).
Which of the following processes takes place in the cytosol of a eukaryotic cell?
glycolysis

Glycolysis, the breakdown of glucose into two molecules of pyruvic acid, takes place in the cytosol, outside the mitochondria.
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?
mitochondrion

All of the steps of cellular respiration except glycolysis take place in the mitochondrion.
Which statement describes glycolysis?
This process splits glucose in half and produces 2 ATPs for each glucose.

In glycolysis, glucose is split into two molecules of pyruvic acid. The released energy is stored in ATP and the electron carrier NADH.
Which statement describes the citric acid cycle?
This process produces some ATP and carbon dioxide in the mitochondrion.

The citric acid cycle breaks down carbon molecules, releasing carbon dioxide and forming some ATP.
Which statement describes the electron transport chain?
This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.

In the electron transport chain, electrons move from one electron carrier to another, eventually reaching oxygen. The released energy is used to make ATPs.
Which of the following equations represents photosynthesis?
Chloroplast

6CO2 + 6H2O → C6H12O6 + 6O2

Photosynthesis requires carbon dioxide and water for the production of sugar and oxygen.
In which of the following organelles does photosynthesis take place?
Chloroplasts

use energy from light to transform carbon dioxide and water into sugar and oxygen.
What connects the two photosystems in the light reactions?
An electron transport chain

An electron transport chain connects the two photosystems in the light reactions.

ATP and NADPH are both products of the light reactions and are used to power the Calvin cycle.
What two molecules are produced by the light reactions and used to power the Calvin cycle?
ATP and NADPH
What provides electrons for the light reactions?
H2O

Electrons are stripped from water in the light reactions of photosynthesis. This is one of the reasons plants need water.
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?
Carbon dioxide (CO2)

Carbon dioxide provides the carbon atoms that are incorporated into sugars in photosynthesis. This is why plants need to take in carbon dioxide.
What transports electrons from the light reactions to the Calvin cycle?
NADPH

NADPH is an electron carrier that picks up electrons in the light reactions and releases them in the Calvin cycle.
The light reactions take place in the _________ and the Calvin cycle takes place in the _________.
thylakoids; stroma

Within the chloroplast, the light reactions take place in the flattened sacs called thylakoids and the Calvin cycle takes place in the thick fluid called the stroma.
A positive reaction for carbohydrate fermentation is indicated by the production of acidic wastes, which turn the phenol red pH indicator ______________.
Yellow

This is a pH indicator that is RED at pH 7 or higher (alkaline)
but turns YELLOW at low pH (acidic). The broth is initially pH
neutral. So, if fermentation occurs, and acid by-products are
formed, the solution will turn yellow.