Question

Monosaccharides are absorbed into the intestine
A. By a sodium-dependent cotransporter for glucose and galactose
B. By a sodium independent facilitated transport for fructose
C. By a sodium independent transporter ( GLUT-2) across the concentraluminal membrane
D. Against a concentration gradient of the sodium-dependent transporter
Choose the most appropriate answer from the option given below:

• A. A, B
• B. B, C
• C. B, C, D
• D. A, B, C, D

Hint:

Intestinal Sugar Absorption:
Apical Glucose/Galactose $\rightarrow$ SGLT1 ($ ext{Na}^+$-dependent active symport).
Apical Fructose $\rightarrow$ GLUT5 (Facilitated diffusion).
Basolateral Exit $\rightarrow$ GLUT2 (Facilitated diffusion).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Intestinal monosaccharide absorption coordinates apical SGLT1 active symport, apical GLUT5 facilitated diffusion, and basolateral GLUT2 exit.

Step 2: Detailed Explanation:
Mechanisms of intestinal hexose absorption:
1. A & D (True): D-Glucose and D-Galactose are absorbed across the apical brush border via SGLT-1 (Sodium-Glucose Cotransporter 1), a secondary active symporter that pumps sugars against their concentration gradient using the electrochemical gradient of $\text{Na}^+$.
2. B (True): D-Fructose is absorbed across the apical membrane via GLUT-5 by sodium-independent facilitated diffusion.
3. C (True): All three monosaccharides exit across the basolateral membrane into the portal circulation via the sodium-independent facilitative transporter GLUT-2.
Therefore, all statements A, B, C, and D accurately describe intestinal absorption.

Step 3: Final Answer:
Thus, the correct choice is A, B, C, D, matching option (D).