Practice important
Secretion
MCQ questions and answers.
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MCQ Questions
1. A secretory epithelial cell releases its product by exocytosis without losing any cytoplasmic material. Which mode of secretion does this represent?
A.
Merocrine secretion
B.
Apocrine secretion
C.
Holocrine secretion
D.
Cytolytic secretion
Correct Answer:
Merocrine secretion
Explanation:
In merocrine secretion, the secretory product is released by exocytosis, while the epithelial cell remains intact and retains its cytoplasm.
2. Which structural change most specifically distinguishes apocrine secretion from merocrine secretion?
A.
Complete disintegration of the secretory cell
B.
Pinching off of the apical cytoplasmic portion with the secretion
C.
Release of secretion only through intercellular spaces
D.
Conversion of the secretory epithelium into connective tissue
Correct Answer:
Pinching off of the apical cytoplasmic portion with the secretion
Explanation:
During apocrine secretion, the apical part of the secretory cell is shed along with the product, whereas merocrine secretion occurs without cytoplasmic loss.
3. A gland releases its secretion only after its entire secretory cell accumulates the product and disintegrates. Which classification and mechanism are correct?
A.
Merocrine; exocytosis without cell damage
B.
Apocrine; loss of only the apical cytoplasm
C.
Holocrine; release through complete cellular disintegration
D.
Paracrine; diffusion through the basement membrane
Correct Answer:
Holocrine; release through complete cellular disintegration
Explanation:
Holocrine secretion involves the destruction of the complete secretory cell, and the cellular debris becomes part of the glandular secretion.
4. A single epithelial cell interspersed among absorptive cells produces and releases mucin. Which is the most appropriate description of this secretory arrangement?
A.
A unicellular exocrine gland formed by a goblet cell
B.
A multicellular endocrine gland lacking a duct
C.
A compound tubular gland formed by several epithelial layers
D.
A holocrine gland whose entire epithelium is shed at once
Correct Answer:
A unicellular exocrine gland formed by a goblet cell
Explanation:
A goblet cell is a single secretory epithelial cell that releases mucin onto an epithelial surface, so it functions as a unicellular exocrine gland.
5. Which feature most directly identifies a multicellular exocrine gland as compound rather than simple?
A.
Presence of secretory epithelial cells
B.
Secretion released by exocytosis
C.
A branched duct system serving the secretory units
D.
Location within an epithelial lining
Correct Answer:
A branched duct system serving the secretory units
Explanation:
A compound exocrine gland has a branched duct system, whereas a simple exocrine gland has an unbranched duct; both may contain secretory epithelial cells.
6. Which pairing correctly relates the secretory mechanism to the cellular material incorporated into the secretion?
A.
Merocrine—whole cell; apocrine—nucleus only; holocrine—no cellular material
B.
Merocrine—none or negligible cytoplasm; apocrine—apical cytoplasm; holocrine—entire cell
C.
Merocrine—basal membrane; apocrine—entire nucleus; holocrine—only secretory vesicles
D.
Merocrine—duct cells; apocrine—basement membrane; holocrine—intercellular fluid
Correct Answer:
Merocrine—none or negligible cytoplasm; apocrine—apical cytoplasm; holocrine—entire cell
Explanation:
Merocrine secretion preserves the cell, apocrine secretion includes the apical cytoplasmic portion, and holocrine secretion incorporates the disintegrated whole cell.
7. An epithelial gland has secretory units connected to an unbranched duct, and its cells discharge products by exocytosis. Which combined description is most accurate?
A.
Simple exocrine gland with merocrine secretion
B.
Compound exocrine gland with holocrine secretion
C.
Simple endocrine gland with apocrine secretion
D.
Compound endocrine gland with merocrine secretion
Correct Answer:
Simple exocrine gland with merocrine secretion
Explanation:
An unbranched duct identifies the gland as simple, its duct-directed release identifies it as exocrine, and exocytosis without cell loss indicates merocrine secretion.
8. Why is a gland that releases its product into a duct classified as exocrine rather than endocrine?
A.
Its secretory cells are always arranged in a single layer
B.
Its product is conveyed to an epithelial surface or lumen through a duct
C.
Its secretory cells necessarily undergo holocrine disintegration
D.
Its product can never contain proteins
Correct Answer:
Its product is conveyed to an epithelial surface or lumen through a duct
Explanation:
Exocrine glands use ducts to deliver secretions to an epithelial surface or internal lumen, whereas endocrine glands release their products without ducts.
9. A secretory epithelial cell remains viable after repeated release of protein-rich vesicles. Which inference about its secretion is best supported?
A.
The cell uses holocrine secretion
B.
The cell uses apocrine secretion with complete cellular loss
C.
The cell most likely uses merocrine secretion
D.
The cell is not part of glandular epithelium
Correct Answer:
The cell most likely uses merocrine secretion
Explanation:
Repeated secretion while the cell remains viable is characteristic of merocrine secretion, in which vesicles fuse with the plasma membrane and release their contents by exocytosis.
10. Which sequence correctly describes the cellular events in holocrine secretion?
A.
Product synthesis, apical blebbing, and immediate cellular repair
B.
Product accumulation, whole-cell breakdown, and release of cellular contents
C.
Vesicle fusion, complete preservation of cytoplasm, and duct branching
D.
Basal secretion, nuclear division, and conversion into a goblet cell
Correct Answer:
Product accumulation, whole-cell breakdown, and release of cellular contents
Explanation:
In holocrine secretion, the product accumulates within the cell, the entire cell disintegrates, and its contents are released as the secretion.
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