16

Q1. Where does the chemical process of digestion begin?

Solution

Oral cavity

Q2. What is assimilation?

Solution

Assimilation is the use of absorbed food or nutrients by the tissues.

Q3. Draw a well-labelled diagram of the human stomach.

Solution

Human stomach:  

Q4. Explain diphyodont dentition.

Solution

Dentition in which animals exhibit two kinds of teeth in their life - first deciduous teeth and second adult teeth - is called diphyodont dentition.

Q5. Name the capsule which covers the hepatic lobule.

Solution

Glisson’s capsule

Q6. Name the physiological process by which complex food substances are converted into simple food substances.

Solution

Digestion

Q7. Name the movements which help to pass the food down through the oesophagus.

Solution

Peristalsis

Q8. Explain the process of emulsification.  

Solution

Because fatty acids are insoluble, they are not absorbed in the blood easily. They are first broken down into small fat droplets called micelles.     Micelles are further moved into mucosa, where they are formed into small protein-coated fat globules called chylomicrons.     Chylomicrons are then absorbed by the lacteal lymph vessels of villi.  

Q9. Name the gland present in the lower jaw.

Solution

Sub-maxillary gland

Q10. What is succus entericus? State its role.

Solution

The mucus secreted by the goblet cells of the intestinal mucosal epithelium and the secretions of the brush border cells of mucosa are together called succus entericus. Enzymes present in the succus entericus act on the products formed during digestion, i.e. dipeptides, disaccharides, monoglycerides and nucleosides, to form simple absorbable products.

Q11. Name the two ducts which form the bile duct.

Solution

The cystic duct and the hepatic duct join to form the common bile duct.

Q12. Name the three regions of the stomach.

Solution

The three regions of the stomach are cardiac, fundus and pylorus.

Q13. Why are humans called heterodonts?

Solution

Human beings show the presence of four types of teeth, i.e. canines, incisors, molars and premolars. Hence, they are called heterodonts.

Q14. Name the enzyme which digests milk proteins in infants.

Solution

Rennin

Q15. Name the lymph vessel which joins villi.  

Solution

Lacteal vessel  

Q16. Name the bile pigments present in bile.

Solution

Bilirubin and biliverdin

Q17. What is the optimal pH for pepsin in the stomach?

Solution

1.8 is the optimal pH for pepsins.

Q18. Draw an outline of the human digestive system. Label any ten parts.

Solution

Human digestive system:   (Label any ten parts)

Q19. Draw the diagrams of    

Section of the small intestine  

Arrangement of teeth human  

Solution

Section of the small intestine:  

     

Arrangement of teeth human:  

   

Q20. State the term used for the protein-coated fat droplets.

Solution

Chylomicrons

Q21. State the role of lysozyme present in the saliva.

Solution

Lysozyme acts as an anti-bacterial agent and prevents infections.

Q22. State the action of the following enzymes and the resulting end-product:

Carboxypeptidase

Sucrase

Nucleosidases

Amylase

Solution

Carboxypeptidase - It acts on proteins, peptones and proteoses. The end-product is dipeptides.

Sucrase - Sucrase acts on sucrose, and the end-products are glucose and fructose.

Nucleosidases - These enzymes act on nucleosides, and the end-products are sugars and nitrogen bases.

Amylase - It acts on starch, and the end-product is disaccharides.

Q23. Name the cells which secrete HCl in the stomach.

Solution

Oxyntic cells

Q24. Write any two causes of indigestion.

Solution

Inadequate enzyme secretion and anxiety

Q25. Write any five reactions which occur in the duodenum.  

Solution

Q26. Name the region of the large intestine where symbiotic microorganisms take their shelter.

Solution

Caecum

Q27. What is the technical term used for temporary milk teeth?

Solution

Deciduous teeth

Q28. Name the vestigial organ which is part of the human digestive system.

Solution

Vermiform appendix

Q29. Name various substances present in bile. State the functions of bile.

Solution

Various substances present in bile are bilirubin, biliverdin, bile salts, cholesterol and phospholipids. Bile helps in breaking down of the fats into small micelles, and this process is called emulsification. Bile also helps in activation of lipases.

Q30. Explain the role of the buccal cavity during digestion.

Solution

The buccal cavity performs mastication of food and facilitates swallowing. The teeth and tongue mix the food thoroughly with saliva. The mucus present in the saliva helps in lubricating food, and it also adheres masticated food particles together into a bolus. The bolus is then swallowed and conveyed into the pharynx.

Q31. Name the enzyme of pancreatic juice which acts on nucleic acids.

Solution

Nuclease

Q32. State the percentage of the total starch which gets hydrolysed in the mouth.  

Solution

30%  

Q33. Name the enzymes present in the saliva.

Solution

Salivary amylase and lysozyme

Q34. What is the function of the gastro-oesophageal sphincter?  

Solution

The gastro-oesophageal sphincter regulates the opening of the oesophagus into the stomach.  

Q35. What are partially hydrolysed proteins called?

Solution

Peptones

Q36. Name three secretions released into the small intestine.

Solution

Bile, pancreatic juice and intestinal juice

Q37. Explain the process of the removal of undigested waste from the body.  

Solution

The undigested material or waste first gets solidified into the coherent faeces and is stored in the rectum.     It initiates the neural reflex which causes an urge for its removal.     The defaecation or egestion of waste occurs through the anal opening by the mass peristaltic movements of the anal muscles which is a voluntary process.  

Q38. State the role of the large intestine.

Solution

Role of the large intestine:

Water is absorbed in the large intestine, and drugs and minerals are also absorbed to some extent.

The large intestine secretes mucus which helps in adhering undigested particles together and lubricates them for an easy passage outside the body.

Q39. Where do you find the sphincter of Oddi?

Solution

The sphincter of Oddi is situated between the opening of the hepatopancreatic duct and the duodenum.

Q40. Name the structure which secretes inactive trypsinogen. How is trypsinogen activated?  

Solution

Trypsinogen is secreted by the pancreas. An enzyme called enterokinase which is secreted by the intestinal mucosa activates trypsinogen.