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Exam Master - Physiology With Questions And Correct Answers Latest Version 2024/2025
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Exam Master - Physiology With QuestionsAnd Correct Answers Latest Version
2024/2025
Sodium moves down its gradient through a carrier protein and simultaneously enables glucose to move
against its gradient through the same carrier protein.
What type of transport is being employed? Answer: Secondary active transport uses energy from an
electrochemical gradient to allow a cosubstrate to move against its own concentration gradient. In this
example, a protein pump called the sodium-glucose cotransporter is used.
Diffusion is the net movement of particles from higher to lower concentrations.
Osmosis is the net movement of water from high concentration to low concentration across a
semipermeable membrane.
Primary active transport uses ATP to move a molecule against its gradient.
A protein pump uses ATP to move two potassium ions into a cell and three sodium ions out of a cell.
What type of transport is being employed? Answer: The pump is the Na/K ATPase. The mechanism
of this pump is classified as primary active transport because it uses ATP to move a molecule against its
gradient.
Osmosis is the net movement of water from high concentration to low concentration across a
semipermeable membrane.
Diffusion is the net movement of particles from higher to lower concentrations.
Secondary active transport uses energy from an electrochemical gradient to allow a cosubstrate to move
against its own concentration gradient.
A solution contains more solutes and less water than body fluids.
What will occur if a red blood cell is placed into this solution? Answer: The solution is hypertonic. If
a RBC (red blood cell) is placed in a hypertonic solution, free water will move out of the cell, but it will
use osmosis rather than active transport. This will result in the cell having a higher solute concentration
but a lower volume overall. Since the cell will lose fluids, it will appear shriveled.
,Conversely, a RBC placed into a hypotonic solution will gain water. It will swell as intracellular volume
increases and may potentially burst.
Net movement of water is directed across a cell membrane, into a cell.
What type of solution has the cell been immersed in? Answer: Hypotonic solutions have lower
concentrations of solutes than cells do. When a cell is placed into a hypotonic solution, water enters the
cell.
When a cell is placed into a hypertonic solution, water leaves the cell.
No net movement of water will occur when a cell is placed in an isotonic solution because the solute
concentration is equal between the extracellular and intracellular spaces.
An osmotic solution is one in which water can simply pass across a semipermeable membrane. Osmotic
solutions can be hypertonic, hypotonic, or isotonic.
The cytoplasm contains a certain type of body fluid.
What ion most determines the osmolarity of this type of fluid? Answer: The body fluid that
composes the cytoplasm is intracellular fluid. The osmolarity of intracellular fluid is determined most by
potassium ions, which have the highest concentration of the simple ions in this fluid space.
Calcium is not a primary determinant of the osmolarity of intracellular or extracellular fluid.
Chloride and sodium influence the osmolarity of plasma and interstitial fluid, which are extracellular
fluids.
A lipid bilayer establishes a barrier between a structure's extracellular and intracellular environments.
What type of protein is likely to associate with the concave surfaces of this structure? Answer: The
structure is a biological membrane. BAR proteins have a banana shape that can bind to concave surfaces
of membranes.
Integral proteins have a domain in one layer of the membrane. Transmembrane proteins span the width
of the membrane and have extracellular domains. Peripheral membrane proteins can associate with one
layer of the membrane in a scaffold fashion.
A cell membrane establishes a barrier between a structure's extracellular and intracellular
environments.
, Where in this structure is a transmembrane protein most likely located? Answer: Lipid rafts are
thick areas of a cell membrane that result from phase separations. They provide an area for the
insertion of transmembrane proteins.
Transmembrane proteins span the width of the membrane and have extracellular domains in aqueous
environments, but the aqueous environment is external or internal to the membrane.
Bulk lipids constitute the membrane's main structure without associating with membrane proteins.
Hydrophilic heads are part of the lipid bilayer, but the lipid tails are what can solubilize parts of proteins
due to their hydrophobic nature.
A lipid bilayer establishes a barrier between a structure's extracellular and intracellular environments.
During what phase can lipids move laterally inside this structure? Answer: The phase in which lipids
are able to move laterally inside a bilayer is the liquid disordered phase due to its highly fluid state.
The phase in which lipids exist in a solid phase is the gel phase. Lipids are less able to move laterally in
this phase.
The hybrid of the liquid disordered phase and the gel phase is the liquid ordered phase.
A lipid bilayer contains fatty acids with hydrophilic heads and hydrophobic tails.
How is the fluidity of this structure determined? Answer: The fluidity of biological membranes is
determined by the melting temperature of their constituent tails. Generally, melting temperatures are
influenced by the degree of saturation and the chain length. High unsaturation is associated with low
melting temperatures (higher fluidity), and long chains are associated with higher melting temperatures.
A lipid bilayer establishes a barrier between a structure's extracellular and intracellular environments.
What is primarily responsible for the organization of this structure? Answer: The structure is a
biological membrane, and the primary influence upon the membrane is the hydrophobic effect.
Other forces impact the lipid bilayer to a lesser degree. These include compressive forces due to van der
Waals interactions of the chains, separative forces as the chains switch and swap between
configurations, tight packing of the heads to preempt water penetration of the tails, and expansive
forces of the head.
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