This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Physiology
Glucose and Na+ are transported in GI tract using which mechanism- 
Select and explain. 
A. Secondary active transport, B. Primary active transport, C. Facilitated diffusion, D. Simple diffusion
A: Secondary active transport
Answer: A: Secondary active transport 
Explanation: Ans. is 'a' i.e., Secondary active transport * Co-transport is a type of secondary active transport, e.g. glucose cotransport with Na+.Transport mechanismExamplesSimple diffusionMovement of fats, oxygen, CO2 through lipid portion of membraneFacilitated diffusionMovement of glucose and some amino-acidsOsmosisMovement of water into and out of the cellPrimary active transportIons K+, Na+, Ca++, H+Secondary active transportGlucose or amino-acid into the cell along Na+ (Symport or cotransport)Ca+2, H+ out of the cell against Na+ (Antiport or countertransport)