$$osmolarity = \sum n_i \times C_i$$

Question 1

Which of the following best describes the role of HCl in the stomach during digestion?

Accepted Answer

It denatures proteins and activates pepsinogen to pepsin.

Question 2

Which structure increases the surface area for absorption in the small intestine?

Accepted Answer

Microvilli

Question 3

A patient is unable to digest fats efficiently. Which enzyme is most likely deficient?

Accepted Answer

Lipase

Question 4

Which of the following is TRUE about facilitated diffusion across a cell membrane?

Accepted Answer

It uses channel or carrier proteins to move substances down their concentration gradient.

Question 5

What is the correct formula for calculating osmolarity of a solution?

Accepted Answer

$$osmolarity = \sum n_i 	imes C_i$$

Question 6

Which of the following statements about phospholipids in cell membranes is CORRECT?

Accepted Answer

Phospholipids spontaneously form a bilayer with hydrophilic heads facing aqueous solution.

Question 7

A solution contains 50 mM NaCl and 50 mM glucose. What is its total osmolarity?

Accepted Answer

$$150\,mOsm$$

Question 8

Which process allows monosaccharides and amino acids to be absorbed from the small intestine into the bloodstream?

Accepted Answer

Facilitated diffusion and active transport via membrane proteins

Question 9

Which of the following best explains why multiple small lipid droplets are more efficiently digested than a single large droplet?

Accepted Answer

Smaller droplets have a higher surface area to volume ratio, allowing more enzyme interaction.

Question 10

Which of the following is a function of tight junctions in intestinal epithelial cells?

Accepted Answer

They prevent contents of the intestine from entering between cells.

Question 11

Which of the following is TRUE about the sodium-potassium ATPase (Na$$^+-K$^+$$ pump)?

Accepted Answer

It requires ATP to move Na$$^+$$ out and K$$^+$$ into the cell against their gradients.

Question 12

Which of the following molecules can cross the intestinal epithelial cell membrane by simple diffusion?

Accepted Answer

Fatty acids

Question 13

Which of the following is a correct description of a steroid molecule?

Accepted Answer

It contains a carbon skeleton of 4 rings and is non-polar.

Question 14

Which of the following best describes the formation of an ester linkage in a triglyceride?

Accepted Answer

It forms by a dehydration reaction between glycerol and fatty acids.

Question 15

Which of the following factors does NOT directly affect the rate of diffusion across a membrane according to Fick's law?

Accepted Answer

Amount of ATP available

Question 16

According to Fick's law, which equation correctly represents the rate of diffusion ($$Q_s) $$across a membrane?

Accepted Answer

$$Q_s = D A \frac{(C_2$ - C_1$)}{x}$$

Question 17

Which of the following is a function of the epithelial tissue lining the digestive tract?

Accepted Answer

It produces secretions and acts as a barrier against pathogens.

Question 18

Which of the following statements about the fluid mosaic model of cell membranes is CORRECT?

Accepted Answer

Proteins are embedded within a phospholipid bilayer.

Question 19

Which of the following is a correct statement about passive transport?

Accepted Answer

It moves substances from high to low concentration without energy input.

Question 20

Which of the following is a real-world example of active transport in human physiology?

Accepted Answer

Absorption of glucose from the gut via sodium-glucose cotransporter

Digestive System and Cell Membranes: Structure, Function, and Transport

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