Micro Test 2 ( Mastering)
Which of the following terms refers to pathways that can function both in anabolism and catabolism?
Amphibolic pathways
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 is the function of GTP?
An energy carrier
A strictly fermentative bacterium produces energy
By glycolysis only.
What occurs at the bridge step?
Decarboxylation of pyruvic acid
Why does FADH2 yield less ATP than NADH?
FADH2 electrons enter the electron transport chain at a lower energy level.
Based on the animation, how many electron carriers are reduced in the Krebs cycle only?
Four
Which step is the step for which glycolysis is named?
Fourth
Which of the following statements about glycolysis is true?
Glycolysis is also called the Embden-Meyerhof pathway.
The respiration of glucose (cellular respiration) typically involves which three principal stages?
Glycolysis, Krebs cycle, and the electron transport chain
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.
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.
The purpose of electron transport is to create a proton (concentration/gradient/pump) across a membrane for the process of chemiosmosis?
gradient
A reduced molecule
has gained electrons
Which of the following statements is MOST accurate concerning metabolism?
Metabolism is all the chemical reactions of an organism both anabolic and catabolic
Which of the following can be used as a final electron acceptor for aerobic respiration?
Molecular oxygen
During glycolysis:
NAD+ is reduced to NADH, and there is a net production of 2 ATP molecules by substrate-level phosphorylation.
What are the three important electron carrier molecules
NAD+, NADP+, and FAD
Electrons are delivered to the electron transport chain by?
NADH
Glycolysis produces energy in which form?
NADH and ATP
According to the animation, which compounds provide electrons to the system?
NADH and FADH2
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.
Where does the energy come from to power the formation of GTP?
Succinyl CoA
Changes in temperature or pH can cause enzymes to lose activity. What is a common feature of these two effects?
Temperature and pH affect the rate of substrate binding.
Sulfanilamide is an antimicrobial drug that mimics the shape of an important substrate for a particular bacterial enzyme, thereby inhibiting the enzyme. This type of inhibition is known as?
competitive inhibition
In E. coli, the presence of isoleucine shuts down the enzymatic pathway that results in the synthesis of isoleucine. This is an example of_____?
feedback inhibition
anabolic reactions may be characterized as?
forming large molecules from smaller ones.
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.
According to the animation, oxidative phosphorylation
is a catabolic process.
The Pentose Phosphate Pathway
is an example of anabolism.
Activation energy
is lowered by the action of organic catalysts
Lipases break down
lipids
Enzymes speed up the rate at which chemical reactions occur within a cell because the enzyme______?
lowers the activation energy of the reaction.
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.
electrons move from a donor molecule, which is____, to an acceptor molecule which is____?
oxidized;reduced
Which of the following is the final electron acceptor in aerobic respiration?
oxygen
Which of the following is NOT an electron carrier found within the electron transport chains?
oxygen these are carriers flavoproteins ubiquinones metal-containing proteins chtochromes
Where would you expect to find electron transport chains in a prokaryote?
plasma membrane
An electron transport chain prumps____ across a membrane while transferring ___ from one chemical to another?
protons; electrons
Energy released by the movement of charged particles down and electron transport chain is used specifically for____?
pumping protons across the membrane
During glycolysis, glucose is converted to (pyruvic/acetic/lactic) acid, a molecule that can be used in either fermentation or respiration pathways.
pyruvic acid
Any molecule that serves as an electron acceptor will be______?
reduced
A(n) (oxidation/reduction/transport) reaction is one in which a molecule accepts an electron.
reduction
Most oxidation reactions in bacteria involve
removal of Hydrogen ions and electrons
The molecule that an enzyme acts upon is known as____?
substrate
Under ideal conditions, the fermentation of one glucose molecule by bacterium allows a net gain of how many ATP?
2
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
Under ideal conditions, the complete aerobic oxidation of one molecule of glucose by a bacterium allows a net gain of how many ATP molecules?
38
The end result of electron transport is to produce an electrochemical gradient, which creates?
ADP
What two molecules are produced by the light reactions and used to power the Calvin cycle?
ATP and NADPH
Why is ATP required for glycolysis?
ATP makes it easier to break apart glucose into two three-carbon molecules.
What is the intermediate product formed by pyruvic acid during alcoholic fermentation?
Acetaldehyde
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).
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.
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.
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.
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.
Which of the following statements about anaerobic respiration is false?
It involves glycolysis only.
Which of the following statements about beta oxidation is false?
It is a step in glycolysis.
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 fate of pyruvic acid in an organism that uses aerobic respiration?
It is oxidized in the Krebs cycle.
What is the fate of the NAD+ newly regenerated by fermentation?
It returns to glycolysis to pick up more electrons.
What is the role of pyruvic acid in fermentation?
It takes the electrons from NADH, oxidizing it back into NAD+.
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 is an acid produced by fermentation?
Lactic acid and propionic acid
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
Which of the following is needed as a reactant for the first step of the citric acid cycle?
Oxaloacetic acid
Cellular respiration uses ________ as the final electron acceptor
Oxygen
Without____ as a final electron acceptor, the electron transport chain of aerobic organisms would cease to function.
Oxygen
In the electron transport chain?
Oxygen is the terminal electron acceptor, the last molecule to receive the electrons from the system.
Which of the following nutritional classes of organisms use carbon dioxide (CO2) as their carbon source and use light as their energy source?
Photoautotrophs
What is meant by substrate-level phosphorylation?
Production of ATP by transferring phosphates directly from metabolic products to ADP
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.
How does the proton gradient help ATP synthase to make ATP?
Protons move from outside the membrane to inside the membrane.
What carbon molecules remain at the end of glycolysis?
Pyruvic acid
Which of the best statements best describes ribozymes?
Ribozymes process RNA molecules in eukaryotes
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.
Which of the following is the best definition of fermentation?
The oxidation of glucose with organic molecules serving as electron acceptors
What is the driving force of energy production in steps 6 and 7?
The oxidation of three-carbon compounds
Which step(s) of the Krebs cycle does (do) not produce any usable energy?
The second and seventh steps
Which step involves the release of carbon dioxide?
The third and fourth steps
What is the fate of metabolites during respiration?
They are oxidized completely to carbon dioxide and water.
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 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 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.
How many molecules of ATP can be generated from one molecule of NADH?
Three
The advantage of the pentose phosphate pathway is that it produces all of the following EXCEPT
Three ATPs.
How many net ATPs can be made from one molecule of glucose in glycolysis?
Two
What is the net production of ATP in glycolysis?
Two ATP
What is one difference between ubiquinones and cytochromes?
Ubiquinones are not made of protein; cytochromes are.
According to the animation, what does oxygen get reduced to at the end of the electron transport chain?
Water
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.
Chemiosmosis uses_____ to supply the energy necessary to phosphorylate ADP to ATP?
a protein gradient. because lipid bilayers are impermeable to protons, the transport of protons to one side of the membrane creates electrochemical gradient
During the synthesis of acetyl-CoA from pyruvic acid, _____ is produced.
acetate acid
Enzymes increase the rate of reaction by lowering the (activation/reaction/substrate) energy.
activation
When a noncompetitive inhibitor molecule binds to an (active/allosteric) site on an enzyme, the shape of the active site changes so that the substrate molecules can no longer bind.
allosteric
Although glycolysis requires an input of ATP, this pathway results in a net gain of two ATP, therefor it is ______ pathway.
an exergonic
coenzymes
are organic cofactors
According to the animation, the reactions that occur between glucose and pyruvic acid
can either be anabolic or catabolic.
The process of generating ATP using a proton gradient is referred to as
chemiosmosis.
Nitrobacter bacteria use carbon dioxide () for their carbon source and nitrate ions as an energy source. This organism is a ________.
chemoautotroph
Glycolysis literally means
sugar splitting. (breaking apart sugar)
Energy released in an electron transport chain is derived from?
the movement of protons ??
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.
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.
NAD (nicotinamide adenine dinucleotide) is required for many _____ reactions?
transfer
Redox reactions involve
transfer of energy transfer of electrons oxidation and reduction
Which of the following does not affect the function of enzymes?
ubiquinone