
Concept explainers
Which of the following would you expect to find in or on cells whose main function is absorption?
a. Microvilli
c. Gap junctions
b. Cilia
d. Secretory vesicles

Introduction:
Cells are the smallest structural and functional unit of life. The cell has many specialized structures that perform specific functions that are required for proper growth and development of an organism.
Answer to Problem 1MC
Correct answer:
The cells specialized to perform absorption have microvilli over their surfaces. These are hair-like structures that increase the surface area of the cells.
Justification for the correct answer:
Option (a) is given that the cells whose main function is absorption have microvilli in or on them. The body organs like intestines and kidneys perform the function of absorption. Thus, the cells of these organs should have large surface area. This is accomplished by the presence of microvilli (hair-like structures) that extend outward from the plasma membrane.
These provide a brush lining and increase the area of absorption of various nutrients. They also perform the secretory function of some factors. Microvilli are generally present in the small intestine, surface of egg cells, and white blood cells. Hence, option (a) is correct.
Explanation of Solution
Explanation for incorrect answers:
Option (b) is given that the cells whose main function is absorption have cilia in or on them. The cilia are specialized structures on the surface of the cells and provide motility to the cell, in case of prokaryotes. In case of eukaryotes, they perform the function of moving the contents of the organs further. So, it is a wrong answer.
Option (c) is given that the cells whose main function is absorption have gap junctions in or on them. Gap junctions mainly function to pass the ions and molecules freely through the cells. They help in establishing an electrical communication between the cells. So, it is a wrong answer.
Option (d) is given that the cells whose main function is absorption have secretory vesicles in or on them. The secretory vesicles mediate the vesicular transport of cargo between different cells, like hormones or neurotransmitters. So, it is a wrong answer.
Hence, options (b), (c), and (d) are incorrect.
The cells that are specialized to perform the function of absorption are lined by microvilli.
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Chapter 3 Solutions
Essentials of Human Anatomy & Physiology (12th Edition)
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