Physiology of digestion Questions in English

(C) Herbivorous animals primarily feed on plant-based materials that are rich in cellulose.
To facilitate the digestion of this complex carbohydrate,these animals possess a well-developed appendix that houses symbiotic cellulose-digesting bacteria.
These bacteria break down cellulose into simpler compounds that the animal can absorb and utilize for energy.

(A) During the process of digestion,lipids (fats) are acted upon by enzymes such as lipase.
Lipase breaks down triglycerides into smaller components.
The final products of lipid digestion are fatty acids and glycerol.
Therefore,the correct answer is $A$.

(D) The correct reaction is: Duodenum: Nucleic acids $\xrightarrow{\text{Nucleases}}$ Nucleotides.
Nucleic acids are broken down into nucleotides by the action of nucleases present in the pancreatic juice in the duodenum.
Option $A$ is incorrect because lactose is digested by lactase,not trypsin.
Option $B$ is incorrect because maltose digestion occurs in the small intestine,not the stomach,and it produces two glucose molecules.
Option $C$ is incorrect because amylase acts on starch,not fats,and it is present in the mouth and small intestine.

(B) In the process of protein digestion,$X$ represents the action of pepsin in the stomach,which converts proteins into proteoses and peptones.
$Y$ represents the action of trypsin (or chymotrypsin/carboxypeptidase) in the small intestine,which further breaks down these proteoses and peptones into dipeptides.
Therefore,the correct sequence of enzymes is pepsin and trypsin.

(B) Salivary amylase,also known as ptyalin,is an enzyme present in saliva that initiates the digestion of carbohydrates in the mouth.
This enzyme functions optimally in a slightly acidic to neutral environment.
The optimal pH range for salivary amylase activity is approximately $6.7$ to $6.8$.
Therefore,at a pH of $6.8$,the enzyme exhibits its maximum digestive action.