biology : class11 Diffusion and Filtration : Simple Epithelium, Compound Epithelium, Functions : Epithelial Tissue MCQ Questions and Answers
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Diffusion and Filtration
MCQ questions and answers.
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MCQ Questions
1. Why is simple squamous epithelium particularly suitable for diffusion in pulmonary alveoli?
A.
It provides a short diffusion distance because it consists of a single thin layer of cells
B.
It actively transports oxygen against its concentration gradient
C.
It contains several layers that prevent carbon dioxide loss
D.
It produces mucus that increases the solubility of respiratory gases
Correct Answer:
It provides a short diffusion distance because it consists of a single thin layer of cells
Explanation:
A single layer of flattened cells minimizes the distance across which oxygen and carbon dioxide must diffuse, making simple squamous epithelium efficient for gaseous exchange.
2. A mutation causes the epithelial cells lining an alveolus to become twice as thick without changing the concentration gradient. What is the most likely immediate effect on gas exchange?
A.
The rate of diffusion across the epithelium will decrease
B.
The rate of diffusion will increase because the barrier is stronger
C.
Diffusion will stop only for oxygen but not for carbon dioxide
D.
The direction of diffusion will reverse for both gases
Correct Answer:
The rate of diffusion across the epithelium will decrease
Explanation:
An increased epithelial thickness lengthens the diffusion pathway. With the concentration gradient unchanged, diffusion becomes slower across the thicker barrier.
3. Which arrangement best explains how simple squamous epithelium of a blood capillary supports diffusion between blood and surrounding tissues?
A.
A thin, single-cell barrier separates the blood from tissue fluid
B.
A multilayered barrier actively pumps all solutes into tissues
C.
A thick layer of cells prevents movement of dissolved gases
D.
Ciliated cells propel solutes across the capillary wall
Correct Answer:
A thin, single-cell barrier separates the blood from tissue fluid
Explanation:
Capillary epithelium is thin and simple, so dissolved gases and other small substances can diffuse across it over a short distance.
4. Filtration across the epithelium of Bowman's capsule is most directly promoted by which combination?
A.
A pressure difference and a thin filtration barrier
B.
An absence of pressure difference and a multilayered barrier
C.
Active pumping by epithelial cells and a high concentration of proteins in filtrate
D.
Ciliary movement and an impermeable epithelial surface
Correct Answer:
A pressure difference and a thin filtration barrier
Explanation:
Filtration is driven primarily by pressure, and the thin epithelial filtration barrier permits water and small solutes to pass while restricting larger components.
5. If the pressure driving filtration in a renal filtration barrier falls substantially while the barrier remains structurally unchanged, what will most likely happen?
A.
The rate of filtration will decrease
B.
The rate of filtration will increase because diffusion becomes easier
C.
Filtration will continue at the same rate because pressure is irrelevant
D.
Only large proteins will be filtered more rapidly
Correct Answer:
The rate of filtration will decrease
Explanation:
Filtration depends on a pressure difference across the barrier. A lower driving pressure reduces the movement of fluid and small solutes through the epithelial filtration surface.
6. Which statement best distinguishes diffusion from filtration across an epithelial barrier?
A.
Diffusion is driven by a concentration gradient, whereas filtration is driven mainly by pressure
B.
Diffusion requires pressure, whereas filtration always requires active transport
C.
Diffusion occurs only through compound epithelium, whereas filtration occurs only through simple epithelium
D.
Diffusion moves substances from low to high concentration, whereas filtration moves them against pressure
Correct Answer:
Diffusion is driven by a concentration gradient, whereas filtration is driven mainly by pressure
Explanation:
Diffusion results from random molecular movement producing net movement down a concentration gradient, while filtration is bulk movement caused by a pressure difference.
7. A simple epithelial barrier is equally permeable to two gases, but gas X has a larger concentration gradient across it than gas Y. Which prediction is most appropriate?
A.
Gas X will have a greater net diffusion rate than gas Y
B.
Gas Y will diffuse faster because its gradient is smaller
C.
Both gases will diffuse at identical rates regardless of their gradients
D.
Neither gas will diffuse unless epithelial cells use ATP
Correct Answer:
Gas X will have a greater net diffusion rate than gas Y
Explanation:
When permeability and other conditions are comparable, a steeper concentration gradient produces a greater net diffusion rate across the epithelium.
8. Why would replacing a simple squamous filtration surface with a multilayered epithelium generally reduce filtration efficiency?
A.
The increased thickness would lengthen the path for fluid movement
B.
The additional layers would create a larger pressure difference automatically
C.
Multilayered epithelium always increases the permeability of the barrier
D.
The replacement would eliminate the need for a pressure gradient
Correct Answer:
The increased thickness would lengthen the path for fluid movement
Explanation:
A multilayered epithelium forms a thicker barrier. The longer pathway offers greater resistance to filtration and therefore generally lowers its efficiency.
9. A solute is present at a higher concentration on the tissue side of a simple epithelium than on the blood side. In the absence of active transport, what is its expected net movement?
A.
From tissue fluid toward the blood, down its concentration gradient
B.
From blood toward tissue fluid, against its concentration gradient
C.
No net movement because simple epithelium blocks all solutes
D.
Only movement caused by hydrostatic pressure, regardless of concentration
Correct Answer:
From tissue fluid toward the blood, down its concentration gradient
Explanation:
Diffusion produces net movement from higher to lower concentration, provided the solute can cross the epithelial barrier and no opposing process dominates.
10. Which change would most directly enhance diffusion across a simple epithelial membrane, assuming the membrane remains equally permeable?
A.
Increasing the concentration difference across the membrane
B.
Increasing the thickness of the epithelial layer
C.
Reducing the available epithelial surface area
D.
Removing the concentration difference between the two sides
Correct Answer:
Increasing the concentration difference across the membrane
Explanation:
A larger concentration gradient increases the driving force for net diffusion. Greater thickness and smaller surface area would instead hinder diffusion, while no gradient produces no net movement.
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