CBSE Questions for Class 11 Medical Biology Digestion And Absorption Quiz 16 - MCQExams.com

• The oesophagus is a hollow, muscular tube that connects the mouth to the stomach and also carries food and liquids to the stomach from the mouth.
• It is usually around 9 to 10 inches in adults which begins at the pharynx and passes behind the trachea or windpipe.
• The upper part of the oesophagus is made up of striated or voluntary muscles.
• The middle part is composed of both striated and smooth or involuntary muscles.
• The lower part is made up of smooth muscles only.
• The oesophagus consists of two sphincters.
• The upper oesophagal sphincter is single ringlike cartilage which is both voluntary and involuntary in nature and it prevents food and liquids from entering the windpipe (trachea,)
• The lower oesophagal sphincter is involuntary and prevents gastric acids from travelling into the oesophagus and it opens into the diaphragm.
  
• So, the correct answer is 'Both voluntary and involuntary'.

• Pancreatic secretion contains multiple enzymes to digest proteins, fats, and carbohydrates. The entry of highly acidic food to the small intestine stimulates the secretion of large quantities of water solution of sodium bicarbonate by the pancreatic ductal epithelium as depicted in graph 1. 
• The presence of long-chain fatty acids and peptones in the chyme (partially digested food) results in the secretion of pancreatic digestive enzymes by the acinar cells which are depicted in graphs 2 and 3. 

$$\textbf{Correct answer: B}$$  

$$\textbf{Option (A):}$$  

$$\bullet$$  There are two types of movements in the alimentary canal observed for specific functions. 

$$\bullet$$ Peristaltic movement or peristalsis is responsible for moving down the food through the alimentary canal with the help of contraction and relaxation of the muscles present in the muscularis layer.

$$\textbf{Option (B):}$$  

$$\bullet$$ Segmentary or pendular movements are responsible for churning or the mixing of food with different digestive enzymes present in the alimentary canal. 

$$\bullet$$ This movement is just for facilitating the action of the digestive enzymes on the food. 

$$\bullet$$ This movement does not move the food in a downward direction like the peristaltic movement. 

Hence, the correct answer is option (B).