CBSE Questions for Class 11 Medical Biology Digestion And Absorption Quiz 6 - MCQExams.com

• Both pepsin and trypsin are proteolytic enzymes.
• Pepsin is secreted in the stomach, whereas trypsin is a component of pancreatic juice.
• Pepsinogen is activated to pepsin in the stomach on exposure to hydrochloric acid. The optimum pH for the activity of pepsin is 1.8. 
• Pepsin is a strong endopeptidase and breaks proteins into smaller molecules like peptones, proteOses and peptides. 
• Trypsinogen is activated by the action of enterokinase into active trypsin. Enterokinase is secreted by the duodenal mucosa for activation of trypsinogen.
• Trypsin and chymotrypsin are endopeptidase types of enzymes and are active in alkaline pH i.e., 7.5 to 8.
• They dissociate proteins into peptones and proteoses

Correct Option: C

Explanation: 

• Argentaffin is found in the deep fundus part of the stomach.  It secretes hormone-like gastrin, serotonin, histamine.

• Goblet cells are mucus-producing cells. 

• Pepsinogen is an inactive zymogen that is secreted by chief cells. It is formed in the acidic environment of the stomach.

•  Parietal cells are present in the fundus-body region. It secretes hydrochloric acid and some intrinsic factors.

Hence, pepsinogen is secreted from the chief cells.

Correct Option: B

Explanation:

• Pepsinogen (inactive form) is an enzyme that is released from the stomach.
• The hydrochloric acid converts the inactive pepsinogen to active pepsin.
• Similarly, enterokinase converts the inactive trypsinogen to active trypsin.

Hence, just as hydrochloric acid acts on pepsinogen, so does enterokinase act on trypsinogen.

Correct Option: B

Explanation:

• The daily secretion of saliva is 1.5lts. 

• It has salivary amylase which is ptyalin and has lysozymes. 

Hence, the enzyme secreted by saliva is ptyalin.

• Pancreatic juice is a liquid secreted by the pancreas, which contains a variety of enzymes, including trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, pancreatic lipase, nucleases and amylase. 
• Pancreatic juice is alkaline in nature due to the high concentration of bicarbonate ions. Hence, Pancreatic juice is alkaline in nature and contains a variety of enzymes.

• correct answer is option D.
  
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• The small intestine is the most important part of the alimentary canal for digestion and absorption of food. 
• It has three regions a U-shaped duodenum, a long coiled middle portion jejunum and highly coiled ileum.
• The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine. 
• These modifications increase the surface area for more absorption. Villi are supplied with a network of capillaries and a large lymph vessel called the lacteal.
• It transports lipid molecules. The wall of the intestine is surrounded by the blood vessels which assimilates the food molecules to the different parts of the body.
  
  

Solution

Correct answer is option A.

Explanation for correct option:

• Digestive enzymes play a key role in breaking down the food.
• For example, there are enzymes in our saliva, pancreas, intestines and stomach. They break down fats, proteins and carbohydrates into simpler forms.
• The enzymes break down the food into nutrient pieces until they are small enough to be absorbed into the bloodstream and carried throughout the body.

Solution

Correct answer is option C.

Explanation for correct option:

• Peristalsis is a series of wave-like muscle contractions that moves food to different processing stations in digestive tract. 
• The process of peristalsis starts in oesophagus when a bolus food is swallowed.
• Peristaltic movement is the movement that refers to the constriction and relaxation of muscles of the oesophagus, intestine, and stomach.

Solution

Correct answer is option B.

Explanation for correct option:

• The first segment of the duodenum—the superior part of the duodenum (called the duodenal bulb) is connected to the liver via the hepatoduodenal ligament.
• This connection allows for transportation of nutrients from the small intestine to the liver; it also allows the duodenum to receive bile from the liver.

• Food is digested in stomach and small intestine, Whereas digested food is absorbed by the small intestine.
• The large intestine is the last part of the digestive system where the absorption of water takes place.
• After the absorption of water, the left solid materials are excreted out as feces
  
  Thus, the correct answer is option C.

• After digestion of complex food into the simple soluble form, the nutrients are absorbed by the small intestine with help of finger-like projection (villi) in the wall of the intestine.  
• Assimilation is the process of transfer of soluble food from the intestine to rest parts of the body through blood vessels.

• Most of the digestion and absorption of the food takes place in the small intestine because it is the main organ of absorption and digestion of food. 
• The surface area of the small intestine gets increased for absorption due to the presence of villi which gives food plenty of time to break down properly. Hence, the longest part of the alimentary canal is a small intestine.

• The stomach is made of  4 layers. They are serosa, muscularis, submucosa, mucosa. These layers of smooth muscle consist of the outer longitudinal, the middle circular, and the inner oblique muscles.
• The innermost layer or lining (mucosa) contains the glands that release digestive juices which includes pepsin, chymotrypsin, hydrochloric acid etc. Hence, The inner layer of the stomach releases digestive juices.

$$\textbf{Correct answer: D}$$ 

$$\textbf{Option (D):}$$ 

1. Incisors                                    c. Cutting teeth

$$\bullet$$ The incisors act as the cutting teeth because they are responsible for cutting the food. 

$$\bullet$$ While eating, incisors cut the food into fragments. 

$$\bullet$$ Canines are called tearing teeth because they help with the steering of muscles. 

$$\bullet$$ Canines are important for flesh-eating animals. 

$$\bullet$$ Premolars are called cracking teeth as it cracks the food into small fragments. 

$$\bullet$$ The molars are called grinding teeth because it helps in grinding the food and mastication. 

$$\bullet$$ Therefore the correct sequence of teeth with their specific function will be: 1 - c, 2 - d, 3 - b, 4 - a

Hence, the correct answer is option (D).

• Most of the digestion occurs in the first part of the small intestine while the absorption of broken down nutrients, water, vitamins, and minerals occurs in the rest of the part of intestine. 
• Once nutrients are absorbed by the intestine, they pass into the blood stream and are carried to the liver. Hence, Digested food after absorption comes into the blood.

$$\textbf{Correct answer: D}$$ 

$$\textbf{Option (D):}$$ 

$$\bullet$$ The number of teeth in an adult human is 32.

$$\bullet$$ There are different types of teeth including 8 incisors, 4 canines, 8 premolars and 12 molars. All the types of teeth are present in the two jaws.

Hence, the correct answer is option (D).