CBSE Questions for Class 11 Medical Biology Digestion And Absorption Quiz 13 - MCQExams.com

$$\textbf{Correct answer: D}$$ 

$$\bullet$$ The pH of a solution is the negative logarithm of hydrogen ion concentration in it. 

$$\bullet$$ The pH of the small intestine is 7.5.

$$\bullet$$ The pH of the large intestine is 5.5.

$$\bullet$$ The difference in pH between the small intestine and the large intestine is 2.

$$\bullet$$ The fold change of hydrogen ion concentration will be $$10^2$$ = 100.

$$\bullet$$ This is because the fold change depends on a logarithmic scale. 

Hence, the correct answer is option (D).

• The oesophagus is a hollow distensible muscular part of the alimentary canal.
• The ability to stretch and expand is called distensibility.
• The distensibility of the oesophagus allows any kind of food to pass through it with ease.
• The oesophagus dilates and propels the food from the region of the pharynx to the stomach.
• The stomach is a J shaped distensible bag like structure and is a highly distensible part of the alimentary canal.
• It may take varying shapes and can hold about 1 litre of food.
• The gastric folds in the inner walls of the stomach allow it to get expanded.
• So, the correct answer is 'Stomach'.

1) Ringworm causes contagious fungal infection on the outer layer of skin. 

2) Pinworm infection is an infection of the large intestine and anal area by a small, white parasite, pinworm. Pinworms are also called Threadworm due to their thread-like appearance.

4) Tapeworms are flatworms that can live in the intestines and cause infection.  

So the correct answer is  A ‘Ringworm’.

• The stomach stores food for 3-4 hours or more, before it moves into intestine for further digestion.
• Gastric glands secretes an enzyme, pepsin, Hcl and water into the stomach.
• Casein present in the milk is converted into curd by an enzyme rennin.
• Thus, all statements are true. Option D is correct.

• Serosa is the outermost layer that consists of a secretory epithelial layer and a thin connective tissue layer that reduce the friction from muscle movements.
  
• Serous membranes secrete a slight amount of lubricating fluid. 
  
• This layer of secretory epithelial cells in a serous membrane is called mesothelium.
• The mucosa is the innermost layer of the digestive tract and the submucosa is a thick layer of loose connective tissue that surrounds the mucosa.
  

• An antacid is a substance that neutralizes stomach acidity and is used as a remedy for heartburn, indigestion, or an upset stomach. 
• Some antacids currently available in the market, contain salts of aluminum, calcium, magnesium, or sodium. 
• Antacids contain alkaline ions that chemically neutralize stomach gastric acid, reducing damage to the stomach lining and esophagus, and relieving pain. 

• Food typically spends 4 to 5 hours in the stomach.
• Rennin is a  chemical action protein is found in the gastric juice of infants.
• The chief cells of the viscus(gastric) glands secrete a little quantity of gastric lipase that contributes tiny to the digestion of fat. 
• chymosin(Rennin) is a proteinase found in the digestive juice of the abdomen of infants which helps in the digestion of Casein. Hence, the Gastric gland never secrets even a small amount of lipase is a false statement.

• Saliva has a pH normal range of 6.2-7.6 with 6.7 being the average pH. Saliva is a dilute fluid over 99% being made up of water. Hence, it cannot be considered highly acidic but slightly acidic.
• Saliva is secreted by 3 pairs of salivary glands (the parotid, the submandibular, and the sublingual glands) in human beings.
  
• An adult human may secrete 1 to 1.5 litres of saliva per day. 
  
• Digestion of starch starts in the mouth by the salivary enzymes (ptyalin) which breaks down cooked starch into maltose.
  

• Lysosomes are  membrane-bound vesicular structures formed by the process

• The main function of stomach is "Storage of food".
• The stomach temporarily store food, which passes from the esophagus to the stomach where it is held for 3 hours or longer. 
• Assimilation of food is the function of intestines, egestion of food is the function of anus and complete digestion of fat takes place in small intestine.
• Thus, Option A is correct.