Biology Practice Test: MCQ Quiz
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What would happen if there was a mutation to Complex I and Complex II of the electron transport chain of cellular respiration so that it could not oxidize NADH?
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The proton gradient would not form because the electrons from NADH could not be obtained. No ATP synthesis would occur.
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The proton gradient would be created more rapidly since NADH would donate its electrons more readily. ATP synthesis would increase.
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The electrons would still pass from Complex III and Complex IV to create a smaller proton gradient. Not as much ATP could be made.
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The protons from the matrix would have to diffuse through the membrane to maintain the proton gradient needed for ATP synthase.
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Electrons from the proton gradient would be donated to Complex I so that it could function normally.
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- 2.
Imagine that there were a high concentration of a strong oxidizing agent in the stroma that is able to spontaneously take electrons from NADpH. The strong oxidizing agent is unable to donate electrons back once it has obtained them. What would you expect to happen to the reactions of photosynthesis?
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The light reactions would slow down since the supply of NADPH would decrease.
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The light reactions would speed up since there would be an increase in electron availability.
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NADPH would be reduced and the Calvin Cycle would occur more rapidly.
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NADPH would be oxidized and the Calvin Cycle would cease to happen.
Correct Answer
A. NADPH would be oxidized and the Calvin Cycle would cease to happen.Explanation
A strong oxidizing agent would mean that it is able to oxidize a molecule by taking it's electrons; this would mean that the oxidizing agent is reduced (gained electrons) because it just oxidized a molecule. In this case, the oxidizing agent would oxidize the NADPH in the stroma. If there isn't any NADPH, it can't enter the Calvin Cycle and it would not be able to synthesize sugars.Rate this question:
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- 3.
At the beginning of oxidative phosphorylation, electrons from NADH are passed to the Complex I protein in the mitochondria. In terms of redox chemistry, what is the role of NADH in this system?
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It is the oxidizing agent
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It is the reducing agent
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It will accept electrons from Complex I and NADH become reduced
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It will donate electrons to Complex I and NADH become reduced.
Correct Answer
A. It is the reducing agentExplanation
NADH acts as the reducing agent in the system. It donates electrons to Complex I in the mitochondria, causing NADH to become reduced. This transfer of electrons is a key step in oxidative phosphorylation, where energy is generated through the electron transport chain.Rate this question:
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- 4.
Why would a molecule of fat yield a more negative change in free energy value than a molecule of glucose?
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A molecule of fat has oxygen-hydrogen bonds, which contain more energy than the carbon-carbon bonds in glucose
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A molecule of fat has more non-polar covalent bonds that absorb more energy when broken than the polar covalent bonds in glucose
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A molecule of fat has more polar covalent bonds that give off more energy when broken than the polar covalent bonds in glucose
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A molecule of fat has a longer chain and therefore has more bonds to release energy, and a molecule of glucose has less available bonds to break
Correct Answer
A. A molecule of fat has more non-polar covalent bonds that absorb more energy when broken than the polar covalent bonds in glucoseExplanation
Nonpolar bonds contain the most energy. A non-polar bond occurs between atoms with similar electronegativity. This is why a mole of fat has more energy than a mole of glucose or a mole of water for example. This is also the reason why glucose is used for "short-term" energy because they can be broken down more rapidly since they absorb less energy to break down due to the fact they don't hold as much chemical potential energy in its polar bonds. Fat molecules are used for the storage of chemical potential energy since it absorbs more energy to break down because it has more energy from it's non-polar bonds.Rate this question:
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- 5.
The movement of electrons down the ETC relies on upon, in part, that the electron entering the chain has high potential energy, which allows the electron to travel along to the end without any outside energy input, rather, releasing free energy in a spontaneous reaction. What is another reason for why the electrons would easily be found traveling down the chain?
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The final electron acceptor, oxygen, is very polar
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The final electron acceptor, oxygen, is electropositive
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The final electron acceptor, oxygen has a relatively high electronegativity, and therefore causes the driving force for the electrons to move down the chain
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The final electron acceptor, oxygen, is electronegative, therefore, the electrons moving down the ETC will be attracted to it
Correct Answer
A. The final electron acceptor, oxygen has a relatively high electronegativity, and therefore causes the driving force for the electrons to move down the chainExplanation
The correct answer is that the final electron acceptor, oxygen, has a relatively high electronegativity, and therefore causes the driving force for the electrons to move down the chain. Electronegativity is a measure of an atom's ability to attract electrons towards itself. Oxygen, being highly electronegative, has a strong attraction for electrons, which creates a favorable environment for the movement of electrons down the electron transport chain (ETC). This attraction helps to maintain the flow of electrons and allows for the release of free energy in a spontaneous reaction.Rate this question:
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- 6.
The following polar amino acids: Serine, Threonine, and Tyrosine make up part of a trans-membrane protein. Where would this portion of the protein most likely be located?
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A. Outside the cell (in the extracellular matrix)
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B. Inside the cell (in the cytoplasm)
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C. Passing through the lipid bilayer of the membrane
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A and B
Correct Answer
A. A and BExplanation
The polar amino acids Serine, Threonine, and Tyrosine indicate that this portion of the protein is hydrophilic. Hydrophilic regions are typically located on the outer surface of the cell membrane, facing the extracellular matrix (outside the cell) or the cytoplasm (inside the cell). Therefore, this portion of the transmembrane protein is most likely located both outside the cell (in the extracellular matrix) and inside the cell (in the cytoplasm).Rate this question:
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- 7.
How many of the following molecules would be able to dissolve in a polar solution? CH4, H2O, NO2, N2, NH3, H2
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1
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2
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3
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4
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5
Correct Answer
A. 3Explanation
H2O, NO2, and NH3 have polar bonds and would dissolve in a polar solution. ("Like dissolves like")Rate this question:
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- 8.
What is the pH of a solution that has an H+ concentration of 1 x10^-2 M?
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2
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100
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10
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2 M
Correct Answer
A. 2Explanation
The pH of a solution is a measure of its acidity or alkalinity. It is determined by the concentration of hydrogen ions (H+). In this case, the solution has an H+ concentration of 1 x 10^-2 M, which is equivalent to 0.01 M. The pH scale ranges from 0 to 14, with a pH of 7 being neutral. Since the solution has a higher concentration of H+ ions, it is considered acidic. A pH of 2 indicates a strong acidity. Therefore, the correct answer is 2.Rate this question:
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- 9.
The concentration of OH- inside the thylakoid is 10^-10 M and the concentration of OH- in the stroma is 10^-3 M. Why does this environment allow for ATP synthase to form ATP?
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There is a higher pH in the thylakoid so protons can be pumped out of the thylakoid via ATP synthase and synthesize ATP.
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There is a lower pH in the thylakoid so protons can be pumped out of the thylakoid via ATP synthase and synthesize ATP.
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The smaller proton gradient in the thylakoid would allow ATP synthase to use the protons in the gradient to make ATP.gradient in the stroma to move protons to the thylakoid and synthesize ATP in the thylakoid.
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There is high hydroxyl concentration in the the thylakoid which can move through the ATP synthase and make ATP.
Correct Answer
A. There is a lower pH in the thylakoid so protons can be pumped out of the thylakoid via ATP synthase and synthesize ATP.Explanation
The lower pH in the thylakoid creates a proton gradient, with a higher concentration of protons in the thylakoid lumen compared to the stroma. This proton gradient allows ATP synthase to pump protons out of the thylakoid and into the stroma, using the energy from this movement to synthesize ATP. Therefore, the lower pH in the thylakoid enables ATP synthase to form ATP.Rate this question:
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- 10.
Let’s say that your blood has an unusually high concentration of H+ ions. Using your knowledge of the bicarbonate buffering system, what would happen to restore equilibrium?
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The H+ ions would combine with bicarbonate (HCO3-) to form carbonic acid (H2CO3), which would dissociate to form CO2 and H20. CO2 would be exhaled.
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Respiration would increase and subsequently increase CO2 in the blood, which would combine with the H+ to neutralize the H+ ions.
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The H+ ions would combine with carbonic acid (H2CO3) to increase bicarbonate (HCO3-), which is a base, thereby neutralizing the acidity.
Correct Answer
A. The H+ ions would combine with bicarbonate (HCO3-) to form carbonic acid (H2CO3), which would dissociate to form CO2 and H20. CO2 would be exhaled.Explanation
The H+ ions combine with bicarbonate (HCO3-) to shift the equilibrium towards making more CO2 and H2O. It wouldn't be able to combine with H2CO3 because already has as many hydrogen molecules as it can hold. Your body would not respond by breathing more because that would increase the CO2 concentration and shift the reaction to make more H+ and HCO3-. This does not happen because the blood already has a high [H+] and it would not want to make your blood any more acidic.Rate this question:
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- 11.
How many molecules of G3P could be synthesized in the Calvin Cycle if there is an abundant source of CO2, 90,000 ATP, and 100,000 NADpH?
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16,666
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11,111
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10,000
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15,000
Correct Answer
A. 10,000Explanation
There is an abundant amount of CO2 so it is not important to worry about that aspect of this question. You know that in the Calvin Cycle, 3 CO2 9 ATP and 6 NADPH are required to make 1 G3P molecule. So if you imagine that you had unlimited CO2 and ATP, 100,000 NADPH would be able to make 16,666 molecules of G3P (100,000/6 = 16,666). If you had unlimited CO2 and NADPH, 90,000 ATP would be able to make 10,000 molecules of G3P (90,000/9 = 10,000). In this case, the amount of ATP that we have limited the amount of G3P we can synthesize to just 10,000 molecules.Rate this question:
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- 12.
A cell releases a signal to neighboring cells to tell them to stop dividing. The cells receiving this information must…
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Have receptors that will bind the signaling molecule, and undergo a signal transduction pathway
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Have receptors that bind to the signaling molecule, respond with the activation of the signal transduction pathway, and finally respond by ceasing cell division
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Have ligands that bind to the signaling molecule, and immediately responds by ceasing further cell division
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Have sugars protruding into the extracellular matrix to sense the signal and cause the activation of the signal transduction pathway, which in turn causes the cell to respond by ceasing further cell division
Correct Answer
A. Have receptors that bind to the signaling molecule, respond with the activation of the signal transduction pathway, and finally respond by ceasing cell divisionExplanation
The correct answer is that the cells receiving the signal must have receptors that bind to the signaling molecule, respond with the activation of the signal transduction pathway, and finally respond by ceasing cell division. This is because the signal released by the cell needs to be detected by the neighboring cells through their receptors. Once the signal binds to the receptors, it triggers a series of intracellular events known as the signal transduction pathway. This pathway ultimately leads to the cells ceasing division in response to the signal.Rate this question:
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- 13.
What is the main difference between primary active transport and secondary active transport?
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Only primary active transport can create an electrochemical gradient
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Secondary active transport only involves the movement of solutes up their gradient
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Primary Active Transporters are considered “pumps” and secondary active transporters are not
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Primary active transport requires ATP and secondary active transport does not
Correct Answer
A. Primary active transport requires ATP and secondary active transport does notExplanation
Primary active transport requires ATP to directly move molecules against their concentration gradient, while secondary active transport uses the energy stored in the electrochemical gradient of one molecule to drive the transport of another molecule against its concentration gradient. Therefore, the main difference between primary and secondary active transport is the requirement of ATP.Rate this question:
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- 14.
When you walk, you must place your foot on the ground, in front of you, and push down and back to propel yourself forward. Then, you release your foot from its position, move it forward relative to the ground, and repeat the process. This movement is analogous to the movement of myosin. What function does this action reflect at the cellular level?
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Muscle contraction
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The separation of chromosomes
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The bending of cilia and flagella
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Movement of cargo such as a vesicle
Correct Answer
A. Muscle contractionExplanation
The movement described in the question, where the foot is placed on the ground, pushed down and back to propel forward, and then released and moved forward again, is similar to the process of muscle contraction. Muscle contraction involves the sliding of actin and myosin filaments in muscle cells, which shortens the muscle fibers and generates force for movement. This analogy suggests that the action described reflects the process of muscle contraction at the cellular level.Rate this question:
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- 15.
In a cell, where would you expect to see an H+ concentration of 3.2x10^-5 M?
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A. Matrix of a mitochondria
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B. Smooth endoplasmic reticulum
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C. Nucleus
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D. Lysosome
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E. A and B
Correct Answer
A. D. LysosomeExplanation
Since the [H+]=3.2x10^-5 M, we know that this is acidic. To be exact, the pH is 4.5. The organelle that we know that has a pH this low is a lysosome. The matrix of the mitochondria would not have a low pH since the proton gradient is formed in the intermembrane space, instead it's pH would be higher since there is a low {H+].Rate this question:
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- 16.
A protein does not have beta-pleated sheets or alpha-helices. It was found to have disulfide bridges and hydrophobic interactions. This protein was further examined and revealed that it was made up of one polypeptide chain. Which levels of protein structures are present?
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Primary, Tertiary, Quaternary
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Tertiary only
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Primary, Tertiary
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Primary, Secondary
Correct Answer
A. Primary, TertiaryExplanation
The presence of disulfide bridges and hydrophobic interactions indicates the formation of tertiary structure in the protein. The fact that the protein is made up of one polypeptide chain suggests that it does not have a quaternary structure involving multiple polypeptide chains. Therefore, the protein has both primary and tertiary structures.Rate this question:
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- 17.
Which of the following is not a similarity between flagella and cilia?
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The way in which they move.
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The 9-2 arrangement of microtubules.
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They both use the motor protein dynein
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Both are found in eukaryotic cells.
Correct Answer
A. The way in which they move.Explanation
Flagella and cilia are both similar in terms of their 9-2 arrangement of microtubules and their use of the motor protein dynein. Both flagella and cilia are found in eukaryotic cells. However, the main difference between flagella and cilia lies in the way they move. Flagella typically have a whip-like motion and are responsible for cell propulsion, while cilia have a coordinated beating motion and are involved in moving substances along the surface of cells.Rate this question:
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- 18.
When water forms hydrogen bonds with other molecules, it…
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Is dissolving a small, polar, or charged molecule
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Is it dissolving a small, polar molecule
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Is only forming hydrogen bonds, because water cannot dissolve anything without breaking bonds
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Is dissolving the molecule by breaking the bonds in that molecule and replacing them with hydrogen bonds
Correct Answer
A. Is dissolving a small, polar, or charged moleculeExplanation
Water is a polar molecule, meaning it has a slightly positive end and a slightly negative end. When water forms hydrogen bonds with other molecules, it can dissolve small, polar, or charged molecules. This is because the positive end of water is attracted to the negative end of the molecule being dissolved, allowing water to surround and separate the molecules, effectively dissolving them.Rate this question:
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- 19.
Cellulose is made of long, linear chains of glucose molecules, which allows for it to be able to provide rigidity to a cell. Why is cellulose be able to provide this function?
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This is because cellulose is polar and can allow the cell membrane of a cell to create a strong covalent bond to it
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This is because cellulose is non-polar, and can allow for extensive hydrogen bonding between its chains
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This is because the cellulose is polar, and can allow for extensive hydrogen bonding between its chains
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This is because cellulose has many non-polar covalent bonds, which are, in general, stronger bonds than polar-covalent bonds, and therefore, will hold its structure well
Correct Answer
A. This is because the cellulose is polar, and can allow for extensive hydrogen bonding between its chainsExplanation
Cellulose is able to provide rigidity to a cell because it is polar and can allow for extensive hydrogen bonding between its chains. Hydrogen bonding is a strong intermolecular force that occurs between the hydrogen atom of one molecule and the oxygen, nitrogen, or fluorine atom of another molecule. In the case of cellulose, the polar hydroxyl groups (-OH) on each glucose molecule can form hydrogen bonds with the hydroxyl groups of adjacent glucose molecules. This results in the formation of a strong and stable network of hydrogen bonds, which provides structural support and rigidity to the cell.Rate this question:
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- 20.
Why do the fatty acid tails of a phospholipid bilayer of the cell membrane orient themselves inwards (towards each other)?
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The fatty acid tails are attracted to each other because the atoms involved are charged
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The fatty acids are very polar and do not want to interact with the non-polar surroundings of the cell (the extracellular fluid and cytosol)
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The fatty acid tails form strong hydrophillic interactions to keep them together
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The atoms that make up the bonds in the fatty acid tails have similar electronegativities
Correct Answer
A. The atoms that make up the bonds in the fatty acid tails have similar electronegativitiesExplanation
The tails are hydrophobic (not attracted to water) because of the high number of non-polar bonds it has because of the high number of C-H and C-C bonds. It doesn't interact with water and prefers to interact with non-polar molecules which is why they orient themselves towards each other. Think about oil in water; these interactions are analogous to fatty acid tails in the cell.Rate this question:
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- 21.
In photosynthesis, sugars are synthesized. The cell must have had an initial input of energy from sunlight in order to synthesize the bonds that are found in the resulting sugar molecule, which contains the energy from sunlight in the form of chemical potential energy. Which of the following must be true about the process of photosynthesis?
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NADPH contributes to the H+ gradient, which provides the energy to drive the formation of sugars
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High energy electrons (which obtain energy from the sunlight) gain energy as they move down the ETC, producing the H+ gradient that drives ATP synthesis
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The ATP that is produced in the Light reactions provides the energy that is required to form the bonds in sugars
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The energy released from the breaking of bonds in NADPH at the Calvin Cycle provide the energy to form the bonds between sugars
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B and C
Correct Answer
A. The ATP that is produced in the Light reactions provides the energy that is required to form the bonds in sugarsExplanation
The correct answer is that the ATP that is produced in the Light reactions provides the energy that is required to form the bonds in sugars. This is because ATP is a high-energy molecule that can be used as a source of energy for various cellular processes, including the synthesis of sugars. In photosynthesis, ATP is produced during the light reactions, where energy from sunlight is used to generate ATP through the process of photophosphorylation. This ATP can then be used in the Calvin Cycle, the dark reactions of photosynthesis, to provide the energy needed to form the bonds between sugars.Rate this question:
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- 22.
During ATP synthesis in plant and animal cells, which of the following place(s) would there be a noticeably acidic environment?
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The intermembrane space of the mitochondria
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The lumen of the chloroplast thylakoids
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The matrix of the mitochondria
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A and B
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B and C
Correct Answer
A. A and BExplanation
The high proton gradient is formed in the intermembrane space of mitochondria in eukaryotic cells and also in the thylakoid lumen of photosynthetic organisms. A high proton gradient would have a low pH since there is a high concentration of [H+]. Remember that a low pH is equal to a high proton concentration. Hint: [H+] is the same as saying proton concentration.Rate this question:
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- 23.
The plasma membrane of a cell is beginning to degrade and needs to be repaired. Which of the following structures would begin to synthesize molecules to restore the plasma membrane?
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Smooth Endoplasmic reticulum
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Rough Endoplasmic Reticulum
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Mitochondria
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Golgi apparatus
Correct Answer
A. Smooth Endoplasmic reticulumExplanation
The plasma membrane is composed of lipids. Which organelle do we know of that is responsible for lipid synthesis? That would be the smooth endoplasmic reticulum.Rate this question:
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- 24.
Living organisms that live in the presence of oxygen are susceptible to having their DNA damage by oxidation. Antioxidants are molecules that are able to donate electrons to DNA and repair damage done to the DNA. What role do antioxidants play in reduction/oxidation reactions in organisms?
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The antioxidants are oxidizing agents and oxidize the damaged DNA.
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The antioxidants are oxidizing agents and reduce the damaged DNA.
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The antioxidants are reducing agents and reduce the damaged DNA.
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The antioxidants are reducing agents and oxidize the damaged DNA.
Correct Answer
A. The antioxidants are reducing agents and reduce the damaged DNA.Explanation
Antioxidants are reducing agents because they are able to donate electrons to another molecule. Once the antioxidant donates its electrons, the antioxidant becomes oxidized. The damaged DNA accepts these electrons and the damaged DNA becomes reduced since it has accepted the electrons from the antioxidant.Rate this question:
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Nov 26, 2013Quiz Created by
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