Membrane Proteins
(Integral & Peripheral)
(Integral & Peripheral)
Which protein type is embedded within the phospholipid bilayer?
A. Peripheral protein
B. Integral protein
C. Enzyme
D. Cytoskeletal protein
B. Integral proteins are embedded in the hydrophobic core of the membrane, often spanning the bilayer.
Which molecule can cross the phospholipid bilayer by simple diffusion?
A. O₂
B. Na⁺
C. Glucose
D. Starch
A. Small, nonpolar molecules like oxygen diffuse easily through the hydrophobic bilayer.
A cell placed in an isotonic solution will:
A. Shrink
B. Swell
C. Burst
D. Stay the same size
D. In an isotonic solution, water moves in and out at equal rates, resulting in no net change in cell size.
What does x̄ (x-bar) represent?
A. Sample size
B. Standard deviation
C. Mean
D. Error
C. x̄ represents the average value of a data set.
Peripheral proteins are primarily involved in which function?
A. Transport of ions
B. Signal transduction and cell recognition
C. Forming the lipid bilayer
D. Maintaining membrane fluidity
B. Peripheral proteins attach to the membrane surface and commonly function in signaling and cell recognition.
Facilitated diffusion differs from simple diffusion because it:
A. Requires ATP
B. Moves substances against the gradient
C. Uses transport proteins
D. Occurs only in plant cells
C. Facilitated diffusion uses membrane proteins to help polar or charged molecules move down their concentration gradient.
In a hypertonic solution, water will move:
A. Into the cell
B. Out of the cell
C. Equally in and out
D. Against the gradient
B. Water leaves the cell because the surrounding solution has a higher solute concentration.
Which statistic measures the spread of data?
A. SD
B. SEM
C. Mean
D. x̄
A. Standard deviation describes how far data points vary from the mean.
Which statement correctly compares integral and peripheral proteins?
A. Both span the membrane
B. Only peripheral proteins are amphipathic
C. Integral proteins interact with the hydrophobic core
D. Peripheral proteins require ATP
C. Integral proteins contain hydrophobic regions that interact with the nonpolar interior of the phospholipid bilayer.
Which factor most limits membrane permeability?
A. Temperature
B. Hydrophobic interior of the bilayer
C. Cell size
D. Presence of ribosomes
B. The hydrophobic core prevents most polar and charged substances from crossing the membrane.
A plant cell in a hypotonic solution becomes:
A. Plasmolyzed
B. Flaccid
C. Turgid
D. Crenated
C. Water entering the plant cell increases turgor pressure, making the cell turgid.
SEM is calculated using which formula?
A. SD × n
B. SD ÷ √n
C. Mean ÷ SD
D. Mean ÷ n
B. SEM decreases as sample size increases, indicating increased reliability of the mean.
Removing peripheral proteins from a membrane would most directly disrupt which process?
A. Osmosis
B. Cell signaling
C. Simple diffusion
D. Phospholipid movement
B. Peripheral proteins play key roles in signal transduction and communication between cells.
Which transport process moves substances from low to high concentration?
A. Simple diffusion
B. Osmosis
C. Facilitated diffusion
D. Active transport
D. Active transport requires energy to move substances against their concentration gradient.
Osmoregulation is best defined as the:
A. Control of solute concentration and water balance
B. Passive movement of water
C. Transport of ions across membranes
D. Breakdown of ATP
A. Osmoregulation maintains stable internal water and solute levels despite external changes.
What does a small SEM indicate?
A. High variation
B. Low reliability
C. Mean is more reliable
D. Small sample size
C. A smaller SEM means the sample mean is a more accurate estimate of the population mean.
Which type of protein is most likely to function as a channel protein?
A. Peripheral protein
B. Cholesterol
C. Glycoprotein
D. Integral protein
D. Channel proteins must span the membrane, which requires being an integral protein.
Which substance would require a transport protein to cross the membrane?
A. CO₂
B. Na⁺
C. O₂
D. N₂
B. Charged ions cannot cross the hydrophobic membrane interior without a transport protein.
Which organism faces the greatest challenge of water gain?
A. Marine fish
B. Desert mammal
C. Freshwater protist
D. Terrestrial plant
C. Freshwater organisms constantly gain water by osmosis and must actively expel it.
Non-overlapping ±2 SEM error bars suggest:
A. No difference between groups
B. Experimental error
C. A statistically significant difference
D. Small sample size
C. Non-overlapping error bars indicate the means are likely significantly different.