Short Answer TypeWho was the originator of the theory of Natural Selection ? Explain the evolution of species by this theory.
Write the causative agent and the most important symptom of each of the following diseases :
(i) Whooping cough
(ii) Tuberculosis
(iii) Measles
(iv) Malaria
Differentiate between :
(i) Spontaneous and Induced Mutation.
(ii) Geographical and Reproductive Isolation.
Long Answer TypeThe carbohydrates are digested by carbohydrases to monosaccharides like glucose,fructose and galactose. Their digestion starts in the buccal cavity and is completed in the small intestine.
1. Digestion in Buccal Cavity : Digestion of carbohydrates starts in the buccal cavity. The enzyme, salivary amylase, hydrolyzes starch into maltose, isomaltose and small dextrins called limit dextrins in almost neutral or slightly alkaline medium. Since food is retained for a short time in the buccal cavity, only 30% of food is hydrolysed in the buccal cavity.
2. Digestion in stomach : Gastric juice does not contain any carbohydrate hydrolysing enzyme. HC1 destroys ptyalin present in food. Thus, there is no digestion of carbohydrates in stomach.
3. Digestion in Intestine : Two types of juices are mixed with chyme in the small intestine. These are pancreatic juice and intestinal juice.
Pancreatic Juice : It contains a carbohydrase enzyme, pancreatic amylase or amylopsin which hydrolyses the remaining starch into disaccharides.
Intestinal juice : It contains six carbohydrates—intestinal amylase, maltose, isomaltose, limit dextrase, sucrose and lactose.
Thus, the entire carbohydrate of the ingested food changes into glucose, fructose and galactose but glucose is the most abundant of all.
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