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Cholera affects millions of people around the world. It causes diarrhea, which can lead to dehydration and even death. Cholera toxin affects a chloride transporter that secretes chloride ion into the lumen of the small intestine. How does cholera toxin lead to dehydration?- a)The toxin turns off the transporter, so the negatively charged chloride pushes water into the lumen
- b)The toxin turns on the transporter, and water follows the ion due to osmosis
- c)The toxin turns on the transporter, and water is actively transported with the ion
- d)The toxin turns off the transporter, so water is no longer exchanged for chloride ion
Correct answer is option 'B'. Can you explain this answer?
Cholera affects millions of people around the world. It causes diarrhea, which can lead to dehydration and even death. Cholera toxin affects a chloride transporter that secretes chloride ion into the lumen of the small intestine. How does cholera toxin lead to dehydration?
a)
The toxin turns off the transporter, so the negatively charged chloride pushes water into the lumen
b)
The toxin turns on the transporter, and water follows the ion due to osmosis
c)
The toxin turns on the transporter, and water is actively transported with the ion
d)
The toxin turns off the transporter, so water is no longer exchanged for chloride ion
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Isaac Bailey answered |
Understanding Cholera Toxin and Dehydration
Cholera is caused by the bacterium Vibrio cholerae, which produces a potent toxin that disrupts normal intestinal function. This leads to severe dehydration, a life-threatening condition.
Mechanism of Cholera Toxin
- Cholera toxin binds to intestinal epithelial cells, leading to the activation of adenylate cyclase.
- This increases cyclic AMP (cAMP) levels in the cell, which in turn activates protein kinase A (PKA).
Effect on Chloride Transporter
- The activated PKA phosphorylates the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride ion channel.
- This phosphorylation opens the CFTR channel, resulting in increased secretion of chloride ions (Cl-) into the intestinal lumen.
Role of Water and Osmosis
- As chloride ions are secreted into the lumen, water follows due to osmosis.
- Osmosis is the movement of water from areas of lower solute concentration (inside the cells) to areas of higher solute concentration (the intestinal lumen where chloride concentration is increased).
- Consequently, this leads to massive water loss from the body, resulting in severe diarrhea and dehydration.
Conclusion
- Thus, the correct answer is option 'B': "The toxin turns on the transporter, and water follows the ion due to osmosis."
- This critical mechanism underscores the importance of rapid rehydration and medical intervention in cholera cases to prevent death.
Cholera is caused by the bacterium Vibrio cholerae, which produces a potent toxin that disrupts normal intestinal function. This leads to severe dehydration, a life-threatening condition.
Mechanism of Cholera Toxin
- Cholera toxin binds to intestinal epithelial cells, leading to the activation of adenylate cyclase.
- This increases cyclic AMP (cAMP) levels in the cell, which in turn activates protein kinase A (PKA).
Effect on Chloride Transporter
- The activated PKA phosphorylates the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride ion channel.
- This phosphorylation opens the CFTR channel, resulting in increased secretion of chloride ions (Cl-) into the intestinal lumen.
Role of Water and Osmosis
- As chloride ions are secreted into the lumen, water follows due to osmosis.
- Osmosis is the movement of water from areas of lower solute concentration (inside the cells) to areas of higher solute concentration (the intestinal lumen where chloride concentration is increased).
- Consequently, this leads to massive water loss from the body, resulting in severe diarrhea and dehydration.
Conclusion
- Thus, the correct answer is option 'B': "The toxin turns on the transporter, and water follows the ion due to osmosis."
- This critical mechanism underscores the importance of rapid rehydration and medical intervention in cholera cases to prevent death.
Which statement represents a notable difference between simple diffusion and facilitated diffusion?- a)Unlike simple diffusion, facilitated diffusion can transport ligands against a concentration gradient.
- b)Unlike simple diffusion, the rate of facilitated diffusion is limited by the number of transport proteins in the membrane.
- c)Unlike simple diffusion, facilitated diffusion requires energy in the form of ATP.
- d)Unlike simple diffusion, facilitated diffusion can occur in any type of cell.
Correct answer is option 'B'. Can you explain this answer?
Which statement represents a notable difference between simple diffusion and facilitated diffusion?
a)
Unlike simple diffusion, facilitated diffusion can transport ligands against a concentration gradient.
b)
Unlike simple diffusion, the rate of facilitated diffusion is limited by the number of transport proteins in the membrane.
c)
Unlike simple diffusion, facilitated diffusion requires energy in the form of ATP.
d)
Unlike simple diffusion, facilitated diffusion can occur in any type of cell.
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Orion Classes answered |
Simple diffusion and facilitated diffusion are both passive processes that involve the movement of molecules across a membrane from an area of higher concentration to an area of lower concentration. However, there are notable differences between the two processes.
In simple diffusion, molecules passively move across the membrane directly through the lipid bilayer without the involvement of any specific proteins. The rate of simple diffusion is influenced by factors such as the concentration gradient, temperature, and molecular size. Simple diffusion does not require transport proteins and is not limited by their availability.
On the other hand, facilitated diffusion involves the movement of molecules across the membrane with the assistance of specific transport proteins, such as channel proteins or carrier proteins. These proteins facilitate the movement of molecules by creating selective channels or by binding to the molecules and undergoing conformational changes. The rate of facilitated diffusion is dependent on the number of available transport proteins in the membrane. If there are limited numbers of transport proteins, the rate of facilitated diffusion can be limited.
Option B correctly states that the rate of facilitated diffusion is limited by the number of transport proteins in the membrane, which is a notable difference compared to simple diffusion.
The rate of osmosis across a cell membrane depends upon which of the following?
I: Intracellular solute concentration
II: Extracellular solute concentration
III: Polarity of solutes
IV: Molecular weight of solutes
V: The presence of aquaporins- a)I, II, and V
- b)I, II, III, IV, and V
- c)I and II
- d)I, III, and IV
Correct answer is option 'A'. Can you explain this answer?
The rate of osmosis across a cell membrane depends upon which of the following?
I: Intracellular solute concentration
II: Extracellular solute concentration
III: Polarity of solutes
IV: Molecular weight of solutes
V: The presence of aquaporins
I: Intracellular solute concentration
II: Extracellular solute concentration
III: Polarity of solutes
IV: Molecular weight of solutes
V: The presence of aquaporins
a)
I, II, and V
b)
I, II, III, IV, and V
c)
I and II
d)
I, III, and IV
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Orion Classes answered |
Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. The rate of osmosis is influenced by several factors:
I. Intracellular solute concentration: The concentration of solutes inside the cell affects the osmotic pressure and determines the direction and rate of water movement.
II. Extracellular solute concentration: The concentration of solutes outside the cell creates an osmotic gradient and influences the movement of water into or out of the cell.
III. Polarity of solutes: The polarity of solutes does not directly affect the rate of osmosis. Osmosis is primarily driven by the concentration gradient of solutes, not their polarity.
IV. Molecular weight of solutes: The molecular weight of solutes does not directly affect the rate of osmosis. Osmosis is driven by the concentration gradient rather than the size or weight of solute molecules.
V. The presence of aquaporins: Aquaporins are specialized channel proteins that facilitate the movement of water across the cell membrane. The presence of aquaporins can significantly increase the rate of osmosis by providing a pathway for water molecules to move more efficiently.
Option A correctly includes factors I, II, and V, which are the key determinants of the rate of osmosis across a cell membrane.
Glucose typically enters the cell through which mechanism?- a)Pinocytosis through a channel protein
- b)Active transport by a glucose transport protein
- c)Simple diffusion through the cell membrane
- d)Facilitated diffusion through a carrier protein
Correct answer is option 'D'. Can you explain this answer?
Glucose typically enters the cell through which mechanism?
a)
Pinocytosis through a channel protein
b)
Active transport by a glucose transport protein
c)
Simple diffusion through the cell membrane
d)
Facilitated diffusion through a carrier protein
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Orion Classes answered |
Glucose, being a polar molecule, cannot easily pass through the cell membrane via simple diffusion because of the hydrophobic interior of the lipid bilayer. Instead, glucose typically enters the cell through facilitated diffusion, which involves the use of carrier proteins. Carrier proteins specific to glucose bind to the molecule on one side of the membrane and undergo a conformational change to transport glucose across the membrane and release it on the other side. This process does not require energy expenditure by the cell and allows glucose to move down its concentration gradient. It is important to note that facilitated diffusion is a passive process and does not require the input of cellular energy.
Which statement best describes how cholesterol affects cell membrane fluidity?- a)Cholesterol increases fluidity at high temperatures and decreases fluidity at low temperatures.
- b)Cholesterol increases fluidity at high temperatures and increases fluidity at low temperatures.
- c)Cholesterol decreases fluidity at high temperatures and decreases fluidity at low temperatures.
- d)Cholesterol decreases fluidity at high temperatures and increases fluidity at low temperatures.
Correct answer is option 'D'. Can you explain this answer?
Which statement best describes how cholesterol affects cell membrane fluidity?
a)
Cholesterol increases fluidity at high temperatures and decreases fluidity at low temperatures.
b)
Cholesterol increases fluidity at high temperatures and increases fluidity at low temperatures.
c)
Cholesterol decreases fluidity at high temperatures and decreases fluidity at low temperatures.
d)
Cholesterol decreases fluidity at high temperatures and increases fluidity at low temperatures.
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Orion Classes answered |
Cholesterol plays a crucial role in modulating the fluidity of the cell membrane. At high temperatures, cholesterol acts as a stabilizing agent by restraining the movement of phospholipids and reducing membrane fluidity. It prevents the phospholipid molecules from packing too closely together, thereby maintaining the integrity and stability of the membrane. This is important because high temperatures can cause the phospholipids to become more fluid and disorganized.
On the other hand, at low temperatures, cholesterol acts as a fluidity buffer by preventing the phospholipid molecules from packing too tightly. It inserts itself between the phospholipids and increases the space between them, allowing for more movement and flexibility in the membrane. This helps to maintain membrane fluidity and prevents the membrane from becoming overly rigid and potentially losing its functionality.
Which of the following organelles is surrounded by a single membrane?- a)Lysosomes
- b)Mitochondria
- c)Nuclei
- d)Ribosomes
Correct answer is option 'A'. Can you explain this answer?
Which of the following organelles is surrounded by a single membrane?
a)
Lysosomes
b)
Mitochondria
c)
Nuclei
d)
Ribosomes
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Orion Classes answered |
Lysosomes are vesicular organelles that digest material using hydrolytic enzymes. They are surrounded by a single membrane. Both mitochondria and nuclei are surrounded by double membranes, eliminating choices (B) and (C). Ribosomes must not be surrounded by membranes because they are found not only in eukaryotes, but also in prokaryotes, which lack any membrane-bound organelles, eliminating choice (D).
Compared to a typical animal cell, the cell membranes on the paw of a polar bear would most likely have an increased concentration of which macromolecule?- a)Unsaturated phospholipids
- b)Saturated phospholipids
- c)Aquaporin proteins
- d)Potassium channel proteins
Correct answer is option 'A'. Can you explain this answer?
Compared to a typical animal cell, the cell membranes on the paw of a polar bear would most likely have an increased concentration of which macromolecule?
a)
Unsaturated phospholipids
b)
Saturated phospholipids
c)
Aquaporin proteins
d)
Potassium channel proteins
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Orion Classes answered |
The cell membranes of polar bear paws would most likely have an increased concentration of unsaturated phospholipids compared to a typical animal cell. Unsaturated phospholipids contain fatty acid chains with double bonds, which introduce kinks in the hydrocarbon chain. These kinks prevent the phospholipids from packing closely together, increasing membrane fluidity. This increased fluidity is advantageous in colder environments because it helps to prevent the cell membrane from becoming too rigid and losing its functionality.
Polar bears live in extremely cold environments, and their paw pads are exposed to low temperatures. By having a higher concentration of unsaturated phospholipids in their cell membranes, the polar bears can adapt to the cold temperatures and maintain proper membrane fluidity. The unsaturated phospholipids allow the cell membranes to remain flexible and functional even at low temperatures.
Aquaporin proteins and potassium channel proteins are not specifically related to membrane fluidity and are involved in other processes such as water transport and ion channel regulation, respectively. Therefore, they are not the most likely macromolecules to have an increased concentration in the cell membranes of polar bear paws compared to a typical animal cell.
Which transport process is responsible for the movement of gases such as oxygen and carbon dioxide across the cell membrane?- a)Diffusion
- b)Osmosis
- c)Facilitated diffusion
- d)Active transport
Correct answer is option 'A'. Can you explain this answer?
Which transport process is responsible for the movement of gases such as oxygen and carbon dioxide across the cell membrane?
a)
Diffusion
b)
Osmosis
c)
Facilitated diffusion
d)
Active transport
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Orion Classes answered |
Diffusion is the process responsible for the movement of gases such as oxygen and carbon dioxide across the cell membrane, as they passively move from areas of high concentration to low concentration.
Which intermolecular process primarily drives the formation of a bilayer when phospholipids are added to water?- a)Lipids cause water to arrange in an ordered, unfavorable cage-like structure. Forcing lipids into a bilayer reduces this effect.
- b)Phospholipids self-assemble into a bilayer due to the strong affinity they have for each other.
- c)The ordered arrangement of a bilayer is more favorable than the disordered state of individual free-floating phospholipids.
- d)A bilayer arrangement maximizes the strength of Van der Waals forces among phospholipids.
Correct answer is option 'A'. Can you explain this answer?
Which intermolecular process primarily drives the formation of a bilayer when phospholipids are added to water?
a)
Lipids cause water to arrange in an ordered, unfavorable cage-like structure. Forcing lipids into a bilayer reduces this effect.
b)
Phospholipids self-assemble into a bilayer due to the strong affinity they have for each other.
c)
The ordered arrangement of a bilayer is more favorable than the disordered state of individual free-floating phospholipids.
d)
A bilayer arrangement maximizes the strength of Van der Waals forces among phospholipids.
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Orion Classes answered |
When phospholipids are added to water, they can form a bilayer structure due to the arrangement of water molecules around the hydrophobic tails of the phospholipids. Water molecules tend to form an ordered structure around hydrophobic molecules, creating a cage-like arrangement. This ordered structure is energetically unfavorable. By forming a bilayer, the hydrophobic tails of the phospholipids are shielded from the water, reducing the formation of the cage-like structure and leading to a more favorable arrangement. Therefore, lipids cause water to arrange in an ordered, unfavorable cage-like structure, and forcing lipids into a bilayer reduces this effect.
Hyperbaric oxygen may be used as a treatment for certain types of bacterial infections. In this therapy, the patient is placed in a chamber in which the partial pressure of oxygen is significantly increased, increasing the partial pressure of oxygen in the patient's tissues. This treatment is most likely used for infections with:- a)obligate aerobic bacteria.
- b)facultative anaerobic bacteria.
- c)aerotolerant anaerobic bacteria.
- d)obligate anaerobic bacteria.
Correct answer is option 'D'. Can you explain this answer?
Hyperbaric oxygen may be used as a treatment for certain types of bacterial infections. In this therapy, the patient is placed in a chamber in which the partial pressure of oxygen is significantly increased, increasing the partial pressure of oxygen in the patient's tissues. This treatment is most likely used for infections with:
a)
obligate aerobic bacteria.
b)
facultative anaerobic bacteria.
c)
aerotolerant anaerobic bacteria.
d)
obligate anaerobic bacteria.
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Orion Classes answered |
Obligate anaerobes cannot survive in the presence of oxygen and would likely be killed by such a therapy, treating the infection. The other types of bacteria listed can all survive in the presence of oxygen and would likely not be treated using this therapy.
Selective serotonin reuptake inhibitors (SSRIs), used to treat depression, block a specific protein in the pre-synaptic neuron to keep the neurotransmitter in the synaptic cleft for a longer period of time. What sort of protein do they block?- a)A neurotransmitter ATP pump
- b)A phagocytosis-inducing protein
- c)A sodium-neurotransmitter symporter
- d)A neurotransmitter channel
Correct answer is option 'C'. Can you explain this answer?
Selective serotonin reuptake inhibitors (SSRIs), used to treat depression, block a specific protein in the pre-synaptic neuron to keep the neurotransmitter in the synaptic cleft for a longer period of time. What sort of protein do they block?
a)
A neurotransmitter ATP pump
b)
A phagocytosis-inducing protein
c)
A sodium-neurotransmitter symporter
d)
A neurotransmitter channel
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Orion Classes answered |
Selective serotonin reuptake inhibitors (SSRIs) work by blocking the reuptake of serotonin, a neurotransmitter, in the pre-synaptic neuron. They specifically target and block the serotonin transporter protein, which is a sodium-neurotransmitter symporter. This protein is responsible for the reabsorption of serotonin from the synaptic cleft back into the pre-synaptic neuron. By blocking this transporter, SSRIs increase the concentration of serotonin in the synaptic cleft, allowing it to interact with and stimulate the post-synaptic receptors for a longer period of time. This helps alleviate symptoms of depression and improve mood.
Pulmonary edema occurs when fluid builds up in the interstitium between the pulmonary capillaries and the alveoli, and eventually enters the alveoli. How do you decrease the risk of pulmonary edema?- a)Decrease hydrostatic pressure and increase osmotic pressure
- b)Increase hydrostatic pressure and decrease osmotic pressure
- c)Decrease hydrostatic pressure and decrease osmotic pressure
- d)Increase hydrostatic pressure and increase osmotic pressure
Correct answer is option 'A'. Can you explain this answer?
Pulmonary edema occurs when fluid builds up in the interstitium between the pulmonary capillaries and the alveoli, and eventually enters the alveoli. How do you decrease the risk of pulmonary edema?
a)
Decrease hydrostatic pressure and increase osmotic pressure
b)
Increase hydrostatic pressure and decrease osmotic pressure
c)
Decrease hydrostatic pressure and decrease osmotic pressure
d)
Increase hydrostatic pressure and increase osmotic pressure
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Orion Classes answered |
Pulmonary edema is the accumulation of fluid in the lungs, specifically in the interstitium and alveoli. To decrease the risk of pulmonary edema, it is necessary to address the factors that contribute to the movement of fluid into the interstitium and alveoli.
Hydrostatic pressure refers to the pressure exerted by fluid within blood vessels, and it tends to push fluid out of the vessels and into the surrounding tissues. To reduce the risk of pulmonary edema, it is important to decrease hydrostatic pressure, which can be achieved by improving heart function, reducing fluid volume, or relieving any obstructions or pressures on blood vessels in the lungs.
Osmotic pressure, on the other hand, is the pressure exerted by solutes (such as proteins) that draw water into the blood vessels. By increasing osmotic pressure, more fluid can be retained within the blood vessels, reducing the likelihood of it leaking into the interstitium and alveoli. This can be accomplished by maintaining adequate levels of proteins, particularly albumin, in the bloodstream.
The nephron reabsorbs glucose through a sodium / glucose transporter. What sort of transporter is it?- a)Protein channel
- b)Antiporter
- c)Sodium pump
- d)ymporter
Correct answer is option 'D'. Can you explain this answer?
The nephron reabsorbs glucose through a sodium / glucose transporter. What sort of transporter is it?
a)
Protein channel
b)
Antiporter
c)
Sodium pump
d)
ymporter
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Orion Classes answered |
The sodium/glucose transporter found in the nephron is a symporter. A symporter is a type of transporter protein that simultaneously moves two different molecules across a cell membrane in the same direction. In this case, the transporter moves both sodium ions and glucose molecules from the tubular fluid in the nephron into the cells of the renal tubules. This process is known as co-transport or secondary active transport, as it utilizes the energy stored in the electrochemical gradient of sodium ions to drive the uphill movement of glucose against its concentration gradient. The symporter binds both sodium and glucose on one side of the membrane and undergoes a conformational change to transport them together into the cell. This allows for the efficient reabsorption of glucose from the filtrate back into the bloodstream, helping to maintain glucose homeostasis in the body.
Which type of transport process involves the release of large particles or substances from the cell?- a)Facilitated diffusion
- b)Endocytosis
- c)Exocytosis
- d)Osmosis
Correct answer is option 'C'. Can you explain this answer?
Which type of transport process involves the release of large particles or substances from the cell?
a)
Facilitated diffusion
b)
Endocytosis
c)
Exocytosis
d)
Osmosis
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Orion Classes answered |
Exocytosis is the process by which cells release large particles or substances from the cell by fusing vesicles containing the material with the cell membrane and expelling the contents outside the cell.
What cell membrane property in the nephron capillaries allows small molecules to pass through?- a)It has cholesterol rafts
- b)It has glycoprotein channels
- c)It has fenestrations
- d)It is amphipathic
Correct answer is option 'C'. Can you explain this answer?
What cell membrane property in the nephron capillaries allows small molecules to pass through?
a)
It has cholesterol rafts
b)
It has glycoprotein channels
c)
It has fenestrations
d)
It is amphipathic
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Orion Classes answered |
Fenestrations are small pores or openings in the endothelial cells lining the capillaries of the nephron. These fenestrations allow small molecules to pass through the capillary walls and enter the surrounding tissues. The presence of fenestrations increases the permeability of the capillaries, allowing for the filtration and exchange of small molecules, such as water, ions, and nutrients, between the blood and the surrounding tissues. This property is important in the function of the nephron, as it allows for the filtration of waste products and the reabsorption of essential substances during urine formation.
What sort of transporters would be required to move glucose from the blood to the lumen?
- a)Apical sodium/glucose symporter and basolateral sodium/potassium pump and glucose channel
- b)Apical glucose channel and basolateral sodium/potassium pump and sodium/glucose symporter
- c)Apical glucose channel and basolateral sodium/potassium pump and sodium/glucose antiporter
- d)Apical sodium/glucose antiporter and basolateral sodium/potassium pump and glucose channel
Correct answer is option 'D'. Can you explain this answer?
What sort of transporters would be required to move glucose from the blood to the lumen?
a)
Apical sodium/glucose symporter and basolateral sodium/potassium pump and glucose channel
b)
Apical glucose channel and basolateral sodium/potassium pump and sodium/glucose symporter
c)
Apical glucose channel and basolateral sodium/potassium pump and sodium/glucose antiporter
d)
Apical sodium/glucose antiporter and basolateral sodium/potassium pump and glucose channel
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Orion Classes answered |
- The apical side faces the lumen, while the basolateral side of the cell is the one closer to the capillary system.
- There is effectively no glucose inside the cell.
- To bring glucose into the cell requires some amount of energy.
- To bring glucose from the blood to the cell, a basolateral glucose channel will allow glucose to move down its gradient. An apical sodium/glucose antiporter will move glucose against its gradient by using the energy of sodium following its gradient. A sodium/potassium pump maintains sodium concentration.
Which molecule diffuses through a membrane most quickly?- a)Ethylene
- b)Glucose
- c)Urea
- d)Benzene
Correct answer is option 'A'. Can you explain this answer?
Which molecule diffuses through a membrane most quickly?
a)
Ethylene
b)
Glucose
c)
Urea
d)
Benzene
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Orion Classes answered |
Ethylene is a small, nonpolar molecule composed of carbon and hydrogen atoms. Nonpolar molecules, like ethylene, can diffuse across a membrane more quickly compared to polar molecules. The lipid bilayer of the cell membrane is primarily composed of hydrophobic tails of phospholipids, creating a barrier to polar molecules. Since ethylene is nonpolar, it can easily dissolve in the lipid bilayer and diffuse through it rapidly.
Glucose, on the other hand, is a polar molecule that cannot passively diffuse across the lipid bilayer due to its hydrophilic nature. It requires specific transport proteins or channels to facilitate its movement across the membrane.
Therefore, ethylene would diffuse through a membrane most quickly among the given options due to its nonpolar nature, allowing it to readily pass through the hydrophobic interior of the lipid bilayer.
In nerve cells, sodium-potassium pumps exchange two K+ for three Na+ across the cell membrane. What is the primary purpose of this exchange?- a)To propagate an action potential
- b)To store electrical and chemical potential energy
- c)To increase the concentration of Na+ inside the cell
- d)To increase the concentration of K+ outside the cell
Correct answer is option 'B'. Can you explain this answer?
In nerve cells, sodium-potassium pumps exchange two K+ for three Na+ across the cell membrane. What is the primary purpose of this exchange?
a)
To propagate an action potential
b)
To store electrical and chemical potential energy
c)
To increase the concentration of Na+ inside the cell
d)
To increase the concentration of K+ outside the cell
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Orion Classes answered |
The primary purpose of the sodium-potassium pump is to maintain the electrochemical gradient across the cell membrane, which is crucial for the proper functioning of nerve cells and other cells in the body. The pump actively transports three sodium ions (Na+) out of the cell while simultaneously importing two potassium ions (K+) into the cell. This exchange helps create a concentration gradient and electrical potential difference across the membrane.
By pumping Na+ out and K+ in, the sodium-potassium pump contributes to the establishment and maintenance of the resting membrane potential, which is necessary for nerve cell excitability. The resting membrane potential allows nerve cells to respond to stimuli and propagate action potentials, which are electrical signals that enable communication within the nervous system.
Additionally, the exchange of Na+ and K+ by the pump helps store potential energy in the form of an electrochemical gradient. This stored energy can be utilized when needed for various cellular processes, such as the generation of action potentials, active transport of other molecules, and maintenance of osmotic balance.
Immune system cells use damaging proteases and reactive oxygen species to destroy foreign invaders. The immune system cells are not harmed because the microbes are sequestered in vesicles. How did the invaders get to the vesicles?- a)Active transport
- b)Phagocytosis
- c)Exocytosis
- d)Pinocytosis
Correct answer is option 'B'. Can you explain this answer?
Immune system cells use damaging proteases and reactive oxygen species to destroy foreign invaders. The immune system cells are not harmed because the microbes are sequestered in vesicles. How did the invaders get to the vesicles?
a)
Active transport
b)
Phagocytosis
c)
Exocytosis
d)
Pinocytosis
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Orion Classes answered |
In the context of the immune system, phagocytosis is the process by which immune cells engulf and internalize foreign invaders such as microbes. During phagocytosis, the immune cell surrounds the invader and forms a vesicle called a phagosome. The phagosome then fuses with lysosomes, forming a phagolysosome, where damaging proteases and reactive oxygen species are released to destroy the invaders.
So, the invaders reach the vesicles through phagocytosis. The immune cells recognize the presence of foreign substances and actively engulf them by extending pseudopods to surround the invaders and internalize them into vesicles for destruction. This sequestration in vesicles allows the immune system to isolate and neutralize the invaders while minimizing harm to the surrounding cells.
How do potassium ions travel as they move into the cell?- a)Down the concentration gradient and up the membrane potential
- b)Up the concentration gradient and down the membrane potential
- c)Down the concentration gradient and down the membrane potential
- d)Up the concentration gradient and up the membrane potential
Correct answer is option 'B'. Can you explain this answer?
How do potassium ions travel as they move into the cell?
a)
Down the concentration gradient and up the membrane potential
b)
Up the concentration gradient and down the membrane potential
c)
Down the concentration gradient and down the membrane potential
d)
Up the concentration gradient and up the membrane potential
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Orion Classes answered |
Potassium ions (K+) move into the cell by a process known as facilitated diffusion, which involves the movement of ions from an area of higher concentration to an area of lower concentration. In the case of potassium ions, they move from the extracellular fluid, where their concentration is higher, to the intracellular fluid, where their concentration is lower.
The movement of potassium ions is also influenced by the membrane potential, which is the difference in electrical charge across the cell membrane. The inside of the cell is negatively charged compared to the outside. This electrical gradient tends to attract positively charged potassium ions into the cell.
Therefore, the overall movement of potassium ions involves moving up the concentration gradient (from high to low concentration) and down the membrane potential (from a more positive to a less positive or negative potential) to enter the cell.
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