Practice important
Absorption
MCQ questions and answers.
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MCQ Questions
1. Which epithelial specialization most directly increases the absorptive surface area of intestinal epithelial cells without significantly increasing the thickness of the epithelial barrier?
A.
Keratinized surface layer
B.
Apical microvilli
C.
Multiple basal cell layers
D.
Intercellular desmosomes
Correct Answer:
Apical microvilli
Explanation:
Microvilli are tiny apical projections that greatly enlarge the surface area available for absorption while maintaining a relatively thin epithelial barrier.
2. The predominance of simple columnar epithelium in the absorptive lining of the small intestine is best explained by which combination of properties?
A.
Many cell layers and extensive protection from abrasion
B.
A single thin layer and elongated cells with enhanced apical surface area
C.
Keratin production and resistance to dehydration
D.
Ciliated surfaces and rapid movement of absorbed nutrients
Correct Answer:
A single thin layer and elongated cells with enhanced apical surface area
Explanation:
Simple columnar epithelium provides only one cellular layer for transport and its elongated cells commonly possess microvilli, making it well suited for absorption.
3. If the microvilli of intestinal epithelial cells were experimentally removed while the epithelial cells remained intact, which change would most directly impair absorption?
A.
A decrease in the total apical membrane area
B.
An increase in the number of epithelial layers
C.
A loss of keratin from the epithelial surface
D.
A reduction in the strength of basement-membrane attachment
Correct Answer:
A decrease in the total apical membrane area
Explanation:
Microvilli expand the apical membrane area, allowing more contact with intestinal contents and more sites for absorptive transport. Their removal therefore reduces absorptive capacity.
4. Which structural arrangement would provide the shortest epithelial diffusion path for substances being absorbed from a body cavity or lumen into underlying tissues?
A.
A multilayered squamous epithelium
B.
A thick keratinized epithelium
C.
A single layer of flattened epithelial cells
D.
A multilayered columnar epithelium
Correct Answer:
A single layer of flattened epithelial cells
Explanation:
Simple squamous epithelium consists of one thin layer of flattened cells, minimizing the distance that substances must cross during absorption.
5. Why is compound epithelium generally less suitable than simple epithelium for efficient absorption across its surface?
A.
It lacks cell junctions required for tissue stability
B.
Its multiple layers create a greater barrier to movement of absorbed substances
C.
Its cells cannot contain cytoplasm or nuclei
D.
It always possesses cilia that remove nutrients
Correct Answer:
Its multiple layers create a greater barrier to movement of absorbed substances
Explanation:
Compound, or stratified, epithelium has several cell layers primarily for protection. These additional layers increase the distance and resistance encountered by substances undergoing absorption.
6. A biopsy shows an intestinal epithelial cell with abundant apical microvilli and a relatively large cytoplasmic region extending toward the basement membrane. Which function is most strongly indicated by this architecture?
A.
Mechanical protection from abrasion
B.
Absorption across an enlarged apical surface
C.
Secretion of mucus from a stratified surface
D.
Prevention of all molecular movement across the epithelium
Correct Answer:
Absorption across an enlarged apical surface
Explanation:
Apical microvilli are a characteristic adaptation for absorption because they increase the membrane area available for uptake from the lumen.
7. Which comparison correctly relates epithelial organization to absorptive efficiency?
A.
Simple epithelium is generally more efficient because fewer layers shorten the transport pathway
B.
Compound epithelium is always more efficient because more layers provide more absorptive cells
C.
Simple epithelium is less efficient because its cells lack a basement membrane
D.
Compound epithelium is more efficient because its outermost cells directly contact the absorbed material
Correct Answer:
Simple epithelium is generally more efficient because fewer layers shorten the transport pathway
Explanation:
A simple epithelium has only one layer of cells, so absorbed substances cross a shorter cellular barrier than they would in compound epithelium.
8. Which observation would most strongly support the identification of an epithelial region as specialized primarily for absorption rather than protection?
A.
Several layers of flattened cells with a thick surface layer
B.
A single layer of columnar cells bearing numerous apical projections
C.
Several layers of cuboidal cells lacking surface projections
D.
A surface composed of dead, keratin-filled cells
Correct Answer:
A single layer of columnar cells bearing numerous apical projections
Explanation:
A single layer reduces the transport barrier, while numerous apical projections increase surface area; together these are strong structural indicators of absorptive specialization.
9. A mutation causes intestinal epithelial cells to become stratified while retaining their apical microvilli only on the surface layer. What is the most likely consequence for absorption?
A.
Absorption will increase because the tissue contains more cells
B.
Absorption will decrease because the added layers increase the transport barrier
C.
Absorption will remain unchanged because only the surface layer contacts the lumen
D.
Absorption will stop because stratified epithelia cannot contain microvilli
Correct Answer:
Absorption will decrease because the added layers increase the transport barrier
Explanation:
Even if the surface cells retain microvilli, additional epithelial layers increase the distance and resistance for substances moving from the lumen into underlying tissues.
10. Which feature would most directly compensate for the relatively limited thickness of a simple absorptive epithelium while maximizing uptake from the lumen?
A.
Reduction of the apical membrane area
B.
Development of apical microvilli
C.
Formation of multiple protective layers
D.
Conversion of living surface cells into keratinized cells
Correct Answer:
Development of apical microvilli
Explanation:
Simple epithelium already minimizes barrier thickness; apical microvilli complement this arrangement by increasing the available surface area for absorption.
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