BIO 361 Biology Practice Exam: Trivia Quiz
(100).jpg "BIO 361 Biology Practice Exam: Trivia Quiz - Quiz")
How much do you know about biology? Biology is a pure science that concentrates on the research of life and living organisms, including their structure, function, development, interactions, evolution, distribution, cells, and nomenclature. The field's scope is extensive, and it is separated into many specialized disciplines such as anatomy, physiology, ethology, and genetics. This quiz will explain whatever you need to know about biology.
- 1.
Why does the rate of glucose transport via Glut-1 only increase up to a certain level, but then stabilize even when external glucose concentration increases?
- A.
Glut-1 transporters become exhausted and stop working.
- B.
All available transporters are working at their maximal rate.
- C.
The driving force for glucose movement has levelled off.
Correct Answer
B. All available transporters are working at their maximal rate.Explanation
The correct answer is that all available transporters are working at their maximal rate. This means that once all the Glut-1 transporters are fully occupied, increasing the external glucose concentration will not result in any further increase in the rate of glucose transport. At this point, the transporters have reached their maximum capacity and cannot transport glucose any faster, leading to a stabilization of the rate of glucose transport.Rate this question:
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- 2.
How could a cell increase its maximum rate of glucose transport?
- A.
Reduce the total number of Glut-1 transporters.
- B.
Reduce internal glucose concentration to increase the driving force for glucose movement.
- C.
Increase internal glucose concentration to increase the driving force for glucose movement.
- D.
Increase the total number of Glut-1 transporters.
Correct Answer
D. Increase the total number of Glut-1 transporters.Explanation
Increasing the total number of Glut-1 transporters would allow more glucose molecules to be transported into the cell at a given time. This would increase the rate of glucose transport as more transporters would be available to facilitate the movement of glucose across the cell membrane.Rate this question:
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- 3.
If you measured desaturase enzyme activity in a goldfish living at 10 degrees Celsius and compared it to desaturase enzyme activity in a goldfish living at 30 degrees Celsius you would expect:
- A.
Desaturase activity to be similar
- B.
Desaturase activity to be higher in the warm fish
- C.
Desaturase activity to be higher in the cold fish
Correct Answer
C. Desaturase activity to be higher in the cold fishExplanation
Desaturase enzymes are responsible for catalyzing the desaturation of fatty acids. In general, enzyme activity tends to increase with temperature up to an optimal point, after which it starts to decrease. Therefore, it is expected that the desaturase enzyme activity in the goldfish living at 30 degrees Celsius (warm fish) would be higher compared to the goldfish living at 10 degrees Celsius (cold fish). This is because the higher temperature provides more energy for the enzyme reaction to occur, resulting in increased enzyme activity.Rate this question:
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- 4.
Which of the following changes will result in an increase in membrane fluidity?
- A.
Increasing the temperature
- B.
Increasing membrane unsaturation
- C.
Decreasing membrane unsaturation
- D.
Both a and b
- E.
Both a and c
Correct Answer
D. Both a and bExplanation
Both increasing the temperature and increasing membrane unsaturation will result in an increase in membrane fluidity. When the temperature is increased, the molecules in the membrane gain more kinetic energy, causing them to move more freely and increasing fluidity. Increasing membrane unsaturation refers to increasing the proportion of unsaturated fatty acids in the membrane. Unsaturated fatty acids have double bonds in their carbon chains, which introduces kinks and prevents tight packing of the lipid molecules. This also increases fluidity as the lipid molecules can move more easily past each other.Rate this question:
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- 5.
Which of the following changes will result in an increase in membrane fluidity?
- A.
Increasing the temperature
- B.
Increasing membrane unsaturation
- C.
Decreasing membrane unsaturation
- D.
Both a and b
- E.
Both a and c
Correct Answer
D. Both a and bExplanation
Increasing the temperature and increasing membrane unsaturation both result in an increase in membrane fluidity. Higher temperatures cause the lipids in the membrane to move more rapidly, making the membrane more fluid. Increasing membrane unsaturation refers to increasing the proportion of unsaturated fatty acids in the membrane phospholipids. Unsaturated fatty acids have double bonds in their carbon chains, which introduce kinks and prevent tight packing of the lipids. This increases the fluidity of the membrane. Therefore, both a and b will lead to an increase in membrane fluidity.Rate this question:
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- 6.
When comparing an Antarctic fish (body temperature ~1 degree Celsius) and a bird (body temperature ~41 degrees Celsius) you would expect:
- A.
The Antarctic fish to have more unsaturated membrane fatty acids
- B.
The bird to have more unsaturated membrane fatty acids
- C.
It is impossible to predict which one would have more unsaturated membrane fatty acids.
Correct Answer
A. The Antarctic fish to have more unsaturated membrane fatty acidsExplanation
The correct answer is that the Antarctic fish is expected to have more unsaturated membrane fatty acids. This is because unsaturated fatty acids have lower melting points and can help maintain fluidity in the cell membranes of organisms living in cold environments. Since the fish in Antarctica has a body temperature of only 1 degree Celsius, it would need more unsaturated fatty acids to adapt to the extreme cold and maintain proper membrane function.Rate this question:
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- 7.
If you measured the membrane fluidity of two artificial bilayers, one containing cholesterol, and one lacking cholesterol:
- A.
The relative fluidity of the bilayers would depend on the temperature of measurement.
- B.
The cholesterol containing bilayer would have higher fluidity.
- C.
The cholesterol containing bilayer would have lower fluidity.
Correct Answer
A. The relative fluidity of the bilayers would depend on the temperature of measurement.Explanation
The relative fluidity of the bilayers would depend on the temperature of measurement. This is because temperature affects the movement of molecules in the bilayer. At higher temperatures, the molecules have more kinetic energy and move more rapidly, resulting in increased fluidity. On the other hand, at lower temperatures, the molecules have less kinetic energy and move more slowly, leading to decreased fluidity. Therefore, the fluidity of the bilayers, including the cholesterol-containing one, would be influenced by the temperature at which the measurement is taken.Rate this question:
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- 8.
___________ is the ability to do work.
- A.
Force
- B.
Energy
- C.
Potential
- D.
Power
Correct Answer
B. EnergyExplanation
Energy is the ability to do work. It is a fundamental concept in physics that describes the capacity of a system to perform tasks or cause changes. Energy exists in various forms such as kinetic, potential, thermal, and electrical. It can be transferred or transformed from one form to another, but it cannot be created or destroyed. In the context of this question, energy is the most appropriate choice as it directly relates to the ability to do work.Rate this question:
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- 9.
Glucose exhibits a(n) _______________ gradient across the cell membrane
- A.
Electrochemical
- B.
Steep
- C.
Chemical
- D.
Electrical
Correct Answer
A. ElectrochemicalExplanation
Glucose exhibits an electrochemical gradient across the cell membrane. This means that there is a combination of both electrical and chemical forces that drive the movement of glucose molecules across the membrane. The electrical component is due to the difference in charge between the inside and outside of the cell, while the chemical component is due to the difference in concentration of glucose on either side of the membrane. Together, these forces create an electrochemical gradient that allows glucose to move into or out of the cell.Rate this question:
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- 10.
As a general rule, lipid-soluble molecules cross membranes by ______________.
- A.
Active transport
- B.
Passive diffusion
- C.
Facilitated diffusion
- D.
All of the above
Correct Answer
B. Passive diffusionExplanation
Passive diffusion is the process by which lipid-soluble molecules cross membranes without the need for energy or assistance from transport proteins. This occurs because the lipid bilayer of the membrane is composed of hydrophobic tails that allow lipid-soluble molecules to easily dissolve and pass through. Active transport requires energy and transport proteins, while facilitated diffusion uses transport proteins but does not require energy. Therefore, the correct answer is passive diffusion as it is the most suitable mechanism for lipid-soluble molecules to cross membranes.Rate this question:
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- 11.
A(n) _______________ facilitates diffusion by binding to its substrate and undergoing a conformational change to transport the substrate across the membrane.
- A.
Permease
- B.
Ion channel
- C.
Porin
- D.
Voltage-gated channel
Correct Answer
A. PermeaseExplanation
Permease is the correct answer because it is a type of protein that facilitates the diffusion of molecules across the membrane by binding to the substrate and undergoing a conformational change. This conformational change allows the substrate to be transported across the membrane. Permeases are commonly found in biological systems and play a crucial role in the transport of various substances across cell membranes.Rate this question:
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- 12.
Which of the following statements is true concerning secondary active transporters?
- A.
An exchanger/antiporter will always be electroneutral
- B.
Electrogenic carriers generate a charge difference across the membrane
- C.
A symporter can bind only one particle
- D.
The direction in which charged particules are transported across the the membrane does not affect the electrical gradient
Correct Answer
B. Electrogenic carriers generate a charge difference across the membraneExplanation
Electrogenic carriers generate a charge difference across the membrane. This means that these secondary active transporters transport charged particles across the membrane, resulting in the establishment of an electrical gradient. This electrical gradient can have important physiological implications, such as influencing the movement of other ions or molecules across the membrane.Rate this question:
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- 13.
The equilibrium potential and the reversal potential for a cell are interchangeable terms, assuming only one ion is being considered.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The equilibrium potential and the reversal potential are indeed interchangeable terms when considering only one ion. Both terms refer to the same concept, which is the membrane potential at which there is no net movement of ions across the cell membrane. This occurs when the electrical gradient and the concentration gradient for the ion are balanced. Therefore, it is correct to say that the equilibrium potential and the reversal potential are interchangeable terms in this context.Rate this question:
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- 14.
The Goldman equation is used to calculate the _____________ of a cell.
- A.
Action potential
- B.
Resting membrane potential
- C.
Reversal potential
- D.
All of the above
Correct Answer
B. Resting membrane potentialExplanation
The Goldman equation is a mathematical formula used to calculate the resting membrane potential of a cell. It takes into account the permeability of the cell membrane to different ions, such as sodium, potassium, and chloride, as well as their concentration gradients. By considering these factors, the Goldman equation can determine the electrical potential difference across the cell membrane when the cell is at rest. This resting membrane potential is important for various cellular processes, including the transmission of nerve impulses and the maintenance of cellular homeostasis.Rate this question:
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- 15.
The main reason the interior of the cell is electronegative at rest is because
- A.
The membrane is more permeable to Na+ than to any other ion
- B.
The Na+/K+ pump is electroneutral
- C.
The membrane is more permeable to K+ than to any other ion
- D.
The interior of the cell contains a much higher concentration of Cl-
Correct Answer
C. The membrane is more permeable to K+ than to any other ionExplanation
The correct answer is that the membrane is more permeable to K+ than to any other ion. This is because the cell membrane contains a higher number of potassium channels compared to other ion channels. As a result, potassium ions can easily move in and out of the cell, leading to a higher concentration of K+ inside the cell. This creates an electrochemical gradient that makes the interior of the cell electronegative at rest.Rate this question:
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- 16.
Compared to the outside of the cell membrane, the inside of the resting cell membrane is typically:
- A.
Electrically neutral
- B.
Extremely variable
- C.
Negatively charged
- D.
Positively charged
- E.
Positively charged whenever the sodium pump is active.
Correct Answer
C. Negatively chargedExplanation
The inside of the resting cell membrane is typically negatively charged. This is because there is a higher concentration of negatively charged ions, such as proteins and organic molecules, inside the cell compared to the outside. Additionally, there is an uneven distribution of ions across the cell membrane, with more positive ions, such as sodium, on the outside and more negative ions, such as potassium, on the inside. This creates an electrical potential difference across the membrane, resulting in a negative charge on the inside.Rate this question:
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- 17.
Calculate the equilibrium potential for Na+ when the intracellular concentration of Na+ is 15mM and the extracellular concentration of Na+ is 145 mM. The temperature is 37C (or 310K). Note the Faraday's constant is 23,062 cal/V. mol, and the gas constant is 1.9872 cal/K. mol
- A.
+60.6mV
- B.
+60.6V
- C.
0.0072V
- D.
-60.6V
- E.
-6-.6mV
Correct Answer
A. +60.6mVExplanation
The equilibrium potential for Na+ can be calculated using the Nernst equation, which is given by:
E = (RT/zF) * ln([Na+]out/[Na+]in)
Where:
E = equilibrium potential
R = gas constant
T = temperature in Kelvin
z = charge of the ion (in this case, +1 for Na+)
F = Faraday's constant
[Na+]out = extracellular concentration of Na+
[Na+]in = intracellular concentration of Na+
Plugging in the given values and solving the equation, we get a positive value of +60.6mV as the equilibrium potential for Na+.Rate this question:
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- 18.
Which of the following would make the membrane potential of a neuron less negative than its resting potential?
- A.
Depolarization
- B.
Hyperpolarization
- C.
Repolarization
- D.
Positively charged ions moving out of the cell
- E.
Negatively charged ions moving into the cell
Correct Answer
A. DepolarizationExplanation
Depolarization is the process in which the membrane potential of a neuron becomes less negative than its resting potential. This occurs when there is an influx of positively charged ions into the cell, causing the inside of the cell to become more positive. As a result, the membrane potential becomes less negative, bringing the neuron closer to its threshold and increasing the likelihood of generating an action potential.Rate this question:
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- 19.
Several molecules of neurotransmitter arrive at the cell membrane of a vertebrae motor neuron dendrite and bind to several of the ligand-gated K+ channels there, stimulating them to open. What will happen next?
- A.
No graded potential will be generated because the cell membrane will hyperpolarize.
- B.
K+ ions will leave the cell, hyperpolarizing the cell membrane.
- C.
An excitatory graded potential will be generated.
- D.
An action potential will be generated.
- E.
K+ ions will enter the cell, depolarizing the cell membrane.
Correct Answer
B. K+ ions will leave the cell, hyperpolarizing the cell membrane.Explanation
When the neurotransmitter molecules bind to the ligand-gated K+ channels on the dendrite of a motor neuron, it stimulates these channels to open. As a result, K+ ions will leave the cell, causing an efflux of positive charge. This efflux of positive charge will result in hyperpolarization of the cell membrane, making it more negative than its resting potential. This hyperpolarization will prevent the generation of a graded potential, inhibiting the generation of an action potential. Therefore, the correct answer is that K+ ions will leave the cell, hyperpolarizing the cell membrane.Rate this question:
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- 20.
Which of the following will happen when a subthreshold excitatory stimulus reaches the axon hillock?
- A.
All of the voltage-gated Na+ channel will open, depolarizing the cell membrane.
- B.
No voltage gated sodium channels will open and the greater potential will continue to travel into the axon, decreasing in magnitude until it dies away completely
- C.
Only some of the voltage gated sodium channels will open, so it will only generate a small action potential
- D.
Only some of the voltage gated sodium channels will open, so it will only generate a graded potential
- E.
An action potential will be generated
Correct Answer
B. No voltage gated sodium channels will open and the greater potential will continue to travel into the axon, decreasing in magnitude until it dies away completelyExplanation
When a subthreshold excitatory stimulus reaches the axon hillock, it means that the stimulus is not strong enough to reach the threshold required to generate an action potential. In this case, no voltage-gated sodium channels will open, preventing the depolarization of the cell membrane. Instead, the greater potential will continue to travel into the axon, but it will decrease in magnitude until it eventually dissipates completely. This process is known as decremental conduction and is characteristic of graded potentials, which do not result in the generation of an action potential.Rate this question:
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- 21.
At the axon hillock, which of the following is most likely to trigger an action potential?
- A.
One excitatory subthreshold graded potential that arrives at exactly the same time as a second subthreshold excitatory graded potential.
- B.
One excitatory threshold graded potential that arrives at exactly the same time as one inhibitory graded potential.
- C.
One excitatory suprathreshold graded potential that arrives just one millisecond after two inhibitory graded potential
- D.
One excitatory subthreshold graded potential that arrives several seconds after another subthreshold excitatory graded potential.
- E.
One excitatory subthreshold graded potential.
Correct Answer
A. One excitatory subthreshold graded potential that arrives at exactly the same time as a second subthreshold excitatory graded potential.Explanation
When two subthreshold excitatory graded potentials arrive at the axon hillock at exactly the same time, they can summate and reach the threshold for an action potential. This is because the combination of the two subthreshold potentials can generate enough depolarization to surpass the threshold and trigger the firing of an action potential.Rate this question:
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- 22.
The axon hillock is incapable of generating an action potential while...
- A.
Its cell membrane is hyperpolarized
- B.
It is in the after hyperpolarization phase of an action potential
- C.
It is in the relative refractory period
- D.
It is in the absolute refractory period
- E.
It is stimulated by a suprathreshold graded potential
Correct Answer
D. It is in the absolute refractory periodExplanation
During the absolute refractory period, the axon hillock is unable to generate an action potential because it is still in the process of repolarizing after a previous action potential. This period is characterized by the inactivation of voltage-gated sodium channels, which prevents the generation of another action potential until the membrane potential returns to its resting state. Therefore, the axon hillock cannot generate an action potential during this period, regardless of the strength of the stimulus.Rate this question:
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- 23.
In a squid giant axon, the length of the relative refractory period is mainly determined by ...
- A.
The binding of neurotransmitters to the voltage gated sodium channels
- B.
The magnitude of the graded potential that stimulated the action potential.
- C.
The length of time that the voltage gated potassium channel remain open
- D.
The timing of the activation gate of the voltage gated sodium channels
- E.
The timing of the inactivation gate of the voltage gated sodium channels
Correct Answer
C. The length of time that the voltage gated potassium channel remain openExplanation
The length of time that the voltage gated potassium channel remains open determines the length of the relative refractory period in a squid giant axon. During the relative refractory period, the membrane potential is hyperpolarized due to the efflux of potassium ions through these channels. This hyperpolarization makes it more difficult for the neuron to reach the threshold for generating another action potential. Therefore, the longer the potassium channels remain open, the longer the relative refractory period will be.Rate this question:
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- 24.
In a squid giant axon, closing of the inactivation gates of the voltage gated Na+ channel ends the ...
- A.
Depolarization phase of an action potential
- B.
Repolarization phase of an action potential
- C.
Afterhyperpolarization phase of an action potential
- D.
Absolute refractory period
- E.
Relative refractory period
Correct Answer
A. Depolarization phase of an action potentialExplanation
Closing of the inactivation gates of the voltage-gated Na+ channel in a squid giant axon ends the depolarization phase of an action potential. During the depolarization phase, the voltage-gated Na+ channels open, allowing the influx of Na+ ions into the axon, which leads to the rapid depolarization of the membrane. Once the inactivation gates close, the Na+ channels become inactive, preventing further influx of Na+ ions and ending the depolarization phase. This is followed by the repolarization phase, where the voltage-gated K+ channels open, allowing the efflux of K+ ions and restoring the membrane potential to its resting state.Rate this question:
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- 25.
Why can action potentials be transmitted over long distances while graded potentials can only be transmitted over relatively short distances?
- A.
Action potentials are self-propagating while graded potentials are not
- B.
Charged ions leak across the membrane when graded potentials are conducted in a neuron, but not when action potentials are conducted
- C.
Action potentials travel only by ions moving through ion channels while graded potentials travel by electronic current spread
- D.
Action potentials travel by electrotonic current spread while graded potentials travel only by ions moving through ion channels
- E.
Action potentials are always larger in magnitude than graded potentials so they can further without dying away
Correct Answer
A. Action potentials are self-propagating while graded potentials are notExplanation
Action potentials are self-propagating, meaning that once initiated, they can regenerate themselves along the length of the neuron without any loss of strength. This is due to the positive feedback mechanism that occurs during the depolarization phase of an action potential. In contrast, graded potentials are not self-propagating and their strength diminishes as they travel along the neuron. This is because graded potentials are generated by the passive spread of ions through the neuron's membrane, and as they spread, they experience leakage and dissipation, resulting in a decrease in strength. Therefore, action potentials can be transmitted over long distances while graded potentials are limited to relatively short distances.Rate this question:
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- 26.
Which of the following options explain why action potentials are normally only conducted in one direction along an axon?
- A.
Voltage gated sodium channels are temporarily inactivated immediately after generating an action potential so even though electronic current travel backward, the sodium channels remain closed
- B.
Myelination prevents retrograde transmission of action potentials by preventing electrotonic current from leaking in the retrograde direction
- C.
Only the axon hillock contains voltage gated sodium channels so only the axon hillock can generate action potentials
- D.
Electrotonic current only travels in one direction along the cell membrane along the cell membrane of the axon
- E.
Voltage gated potassium channels cannot open more than once every few ms, so even tho electrotonic current travel backwards, the potassium channels will remain closed
Correct Answer
A. Voltage gated sodium channels are temporarily inactivated immediately after generating an action potential so even though electronic current travel backward, the sodium channels remain closed -
- 27.
How do neurons convey info about the strength of the signal?
- A.
The frequency of the AP increases as the strength of the signal increases
- B.
The duration of the absolute refractory period decreases as the strength of signal increases
- C.
The speed at which the AP travels increases as the strength of the signal increases
- D.
The polarity of the AP decreases as the strength of the signal increases
- E.
The magnitude of the AP increases as the strength of the signal increases
Correct Answer
A. The frequency of the AP increases as the strength of the signal increasesExplanation
As the strength of the signal increases, the frequency of the action potential (AP) also increases. This means that the neurons fire more frequently to convey the information about the stronger signal.Rate this question:
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Mar 21, 2023Quiz Edited by
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May 26, 2010Quiz Created by
Bambambonk
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