This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Transpo of two substances across the cell membrane in the same direction is known as? 
Select and explain. 
A. Sympo, B. Antipo, C. Exocytosis, D. Pinocytosis
A: Sympo
Answer: A: Sympo 
Explanation: When a carrier protein transpos two or more substances in the same direction, it constitutes a sympo e.g. Na- glucose sympo. When a carrier protein transpos two substances in opposite direction, it is known as antipo. e.g.Na+-H+ antipo in proximal convoluted tubules in the kidney or Na+-K+ ATPase pump. Exocytosis is a type of vesicular transpo. Vesicles with contents are transpoed to the cell membrane. Then they fuse with the cell membrane with the discharge of their contents outside the cell. Pinocytosis is basically endocytosis and the ingested material is liquid. In endocytosis, the sequence of events proceeds in almost the opposite direction of exocytosis. Ref: Principles of Physiology By D. Pramanik, 2007, Page 23; Guyton's physiology 22nd edition, Page 54- 55, Ganong's physiology, 22nd chapter