Scientists in Switzerland compared the total surface area of the small intestine in different species of bats. When the calculations were done as if the inner mucosal surface was smooth, the average inner surface area of the intestinal tube was 9.1 cm2 in one species. The mucosal surface area increased to 48 cm2 when the villi were factored in and reached a total of 0.13 m2 after adding in the membrane surface area of the microvilli. Approximately what percent of the total surface area of the small intestine in these bats can be attributed to the membrane surface area of the microvilli?
A. 12%
B. 78%
C. 55%
D. 96%
E. 28%
Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
Gather Content
· What do you know about microvilli? What other information is related to the question?
Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
D. 96%
Clarify Question
· What is the key concept addressed by the question?
o The question asks about the relative surface area of microvilli.
· What type of thinking is required?
o You are being asked to analyze data to calculate the relative surface area of microvilli of the intestines.
Gather Content
· What do you know about microvilli? What other information is related to the question?
o The epithelial wall of the small intestine is covered with tiny, fingerlike projections called villi. In turn, each epithelial cell lining the villi is covered by many folds of the plasma membrane that form cytoplasmic extensions called microvilli. The microvilli greatly increase the surface area of the intestines to allow for greater nutrient absorption. There are 100 cm in 1 m, so 1 cm = 0.01 m and 1 cm2 = .0001 m2.
Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
o The inner surface of the intestines including villi is 48 c m2 = 0.0048 m2. Microvilli have a surface area of 0.13 m2. If you compare the area with microvilli to the total, you need to subtract the area including villi from the total area to get the area form the microvilli = 0.13-0.0048 = 0.1252 m2. Then divide this area by the total to get the percent of the area attributed to the microvilli 0.1252 m2 /0.130 m2 = 0.96 = 96%. So 96% of the area of the intestines can be attributed to the microvilli.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
o This question asked you to analyze data to calculate the relative surface area of microvilli of the intestines. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that you should compare the area of the total intestines to microvilli? Did you think there were 10 cm per m?
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