Cell Biology Questions
Explore questions in the Cell Biology category that you can ask Spark.E!
Which of the following best characterizes the role of ATP in cellular metabolism?-The charge on the phosphate group of ATP tends to make the molecule very water-soluble.-The free energy released by ATP hydrolysis may be coupled to an endergonic process via the formation of a phosphorylated intermediate.-The release of free energy during the hydrolysis of ATP heats the surrounding environment.-It is catabolized to carbon dioxide and water.-The DG associated with its hydrolysis is positive.
When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle also eventually stop working. Which of the following is the best explanation for this?-They run out of ADP.-A high level of NADH is present in the cell.-Electrons are no longer available from the electron transport chain to power glycolysis and the citric acid cycle.-NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.-The uptake of oxygen stops because electron transport was inhibited.
Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria?ATPAn ATP-dependent proton pumpThe components of the electron transport chainThe production of NADHMovement of electrons down the electron transport chain
If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result?The muscle cells will have more trouble making enough ATP to meet their energy requirements.The cells will not be able to carry out oxidative phosphorylation.The cells will consume glucose at an increased rate.All of the above
The energy given up by electrons as they move through the electron transport chain is used in which of the following processes?The production of NADH and FADH2The production of CO2Pumping H+ across a membraneThe breakdown of glucoseThe oxidation of water
Of the listed metabolic pathways, which is the only pathway found in all organisms?FermentationThe citric acid cycleGlycolysisThe electron transport chainCellular respiration
Which of the following events accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle?Formation of CO2 and synthesis of ATPRelease of CO2 and synthesis of NADHRemoval of coenzyme ARelease of CO2 and release of coenzyme ARegeneration of NAD+
During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction?Carbon dioxideOxygenWaterBoth glucose and carbon dioxideGlucose
Which of the following statements about enzyme function is correct?-Enzymes can greatly speed up reactions, but they cannot change the net energy output because they cannot change the activation energy.-Enzymes can change the equilibrium point of reactions, but they cannot speed up reactions because they cannot change the net energy output.-Enzymes can greatly speed up reactions, but they cannot change the activation energy because they cannot change the net energy output.-Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.-None of the listed responses is correct.
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?-Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a carbon dioxide from the environment, and its reduction by NADH.-Pyruvate is ionized directly to acetyl-coA.-Pyruvate is oxidized, and a molecule of carbon dioxide is removed. The electrons removed in this process are used to reduce NAD+ to NADH.-Pyruvate is oxidized, and a molecule of carbon dioxide is removed. The electrons removed in this process are donated to NADH to produce NAD+.-Pyruvate is reduced, and a molecule of carbon dioxide is removed. The electrons removed in this process are used to oxidize NAD+ to NADH.
Which of the following statements about enzymes is incorrect?-An enzyme is consumed during the reaction it catalyzes.-Enzymes can be used to accelerate both anabolic and catabolic reactions.-An enzyme lowers the activation energy of a chemical reaction.-Most enzymes are proteins.-An enzyme is very specific in terms of the substrate to which it binds.
Which of the following statements about the active site of an enzyme is correct?-The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.-The active site allows the reaction to occur under the same environmental conditions as the reaction without the enzyme.-Coenzymes are rarely found in the active site of an enzyme.-The active site has a fixed structure (shape).-The structure of the active site is not affected by changes in temperature.
A small amount of ATP is made in glycolysis by which of the following processes?Harnessing energy from the sunTransport of electrons through a series of carriersTransfer of electrons and hydrogen atoms to NAD+Attachment of a free inorganic phosphate (Pi) group to ADP to make ATPTransfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
Why is the citric acid cycle called a "cycle"?-The acetyl CoA that enters the cycle is regenerated in the last step of the pathway.-The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle.-NADH is cycled down the electron transport chain.-NAD+ and FAD are recycled.-All of the carbon from glucose is cycled back into the atmosphere as carbon dioxide.
Which of the following processes generates most of the NADH that delivers electrons to the electron transport chain?GlycolysisOxidative phosphorylationSubstrate-level phosphorylationAnabolic pathwaysThe citric acid cycle
The formation of glucose-6-phosphate from glucose is an endergonic reaction and is coupled to which of the following reactions or pathways?-The conversion of glucose + fructose to make sucrose-The active transport of a phosphate ion into the cell-The formation of ATP from ADP + Pi-The hydrolysis of ATP-The contraction of a muscle cell
Most of the ATP produced in cellular respiration comes from which of the following processes?The citric acid cycleGlycolysisReduction of NADHSubstrate-level phosphorylationOxidative phosphorylation
Which of the following is a correct description of the events of cellular respiration in proper sequence?-Glycolysis; oxidative phosphorylation; citric acid cycle; oxidation of pyruvate-Oxidation of pyruvate; citric acid cycle; oxidation of glucose to pyruvate; oxidative phosphorylation-Oxidation of glucose to pyruvate; oxidation of pyruvate; citric acid cycle; oxidative phosphorylation-Oxidation of glucose to pyruvate; reduction of pyruvate; citric acid cycle; oxidative phosphorylation-Glycolysis; reduction of pyruvate; citric acid cycle; oxidative phosphorylation
A molecule becomes more oxidized when it __________.-gains a hydrogen (H+) ion-changes shape-loses an electron-loses a hydrogen (H+) ion-gains an electron
Which describes how the components of the respiratory chain are ordered?A). From high to low ability to pump protons across the inner membraneB). From high to low reduction potential relative to oxygenC). From low to high ability to pass electrons to oxygenD). From low to high free energy relative to oxygenE). From large to small mass