Digestion and Absorption Class 11 Important Extra Questions Biology Chapter 16

Digestion and Absorption Important Extra Questions Very Short Answer Type

Question 1.
How does pepsinogen become active in the stomach?
Answer:
Due to the presence of HCI.

Question 2.
What is pancreatic amylase?
Answer:
The pancreatic juice contains a starch-digesting enzyme called pancreatic amylase.

Question 3.
Name any animal starch.
Answer:
Glycogen.

Question 4.
Name the milk-coagulating enzyme.
Answer:
Chymotrypsin.

Question 5.
Which enzyme is necessary for the digestion of fat?
Answer:
Pancreatic lipase.

Question 6.
Which part of the ruminant stomach secretes gastric juice?
Answer:
Abomasum of the ruminant stomach secretes gastric juice.

Question 7.
Name the water-soluble vitamins.
Answer:
Vitamin B-complex and vitamin C.

Question 8.
State the function of ascorbic acid.
Answer:
It is necessary for the proper development of teeth and gums.

Question 9.
Which is the largest gland in our body?
Answer:
Liver.

Question 10.
Name the cobalt-containing vitamin.
Answer:
Vitamin Bp or Cobalamine.

Question 11.
What are the finger-like projections present in small intestines called?
Answer:
Villi.

Question 12.
Name the enzyme that converts proteins into protons in the stomach.
Answer:
Pepsin.

Question 13.
Name the glands associated with digestion.
Answer:
Salivary glands, liver and pancreas.

Question 14.
Name the acid that takes part in the digestion process.
Answer:
HCI (Hydrochloric acid).

Question 15.
Write four types of teeth present in the human jaw.
Answer:

Incisor,
Canines,
Pre-molar
Molar.

Question 16.
Write two main functions of saliva.
Answer:

Saliva cleans the mouth cavity.
It makes the food soft.

Question 17.
Name the different parts of the larger intestine.
Answer:

Calcium,
Colon,
Rectum.

Question 18.
Name the secretion of liver and pancreatic juice.
Answer:
Bile and pancreatic juice.

Question 19.
Name the largest gland of the human body.
Answer:
Liver.

Question 20.
What is digestion?
Answer:
Digestion is the process of changing food into a simpler form so that it can be used by the body.

Digestion and Absorption Important Extra Questions Short Answer Type

Question 1.
What is the passive absorption of food?
Answer:
It is the absorption of nutrients from higher concentration to lower concentration without the expenditure of energy. This requires the nutrients to be in higher concentration in the intestinal lumen than inside the cell. The diffusion of molecules would continue as long as the concentration difference persists.

The diffusion is a slow process. Water is absorbed by osmosis from the interstitial lumen to the intestinal cells and then to blood as long as the solute concentration is higher in the blood than in the intestinal content.

Question 2.
What do you mean by incomplete and complete type of digestive tracts?
Answer:
The incomplete digestive tract has only one opening for intake of food and elimination of indigestible matter e.g. coelenterates planaria, liver fluke etc. Complete digestive tracts have a separate opening for intake of food and elimination of indigestible matter e.g. in man, frog, rabbit, etc.

Question 3.
What are wisdom teeth? Write the dental formula of permanent and milky teeth.
Answer:

The last molar grown at maturity age in both upper and lower jaws on both sides are called wisdom teeth
The dental formula of permanent teeth = 2, 1, 2, 3/2, 1, 2, 3 = 32; milk teeth = 2, 1, 2, 0/2, 1, 2, 0 = 20

Question 4.
What is the role of
(a) Enterogastrone
Answer:
Enterogastrone slows gastric contractions and stops the secretion of gastric juice.

(b) Cholecystokinin
Answer:
Cholecystokinin of CCK causes the release of bile from the gall bladder and the release of enzymes in pancreatic juice.

(d) Duocrinn
Answer:
Duocrinin causes the release of mucus from Brunner’s glands into the intestinal juice.

(e) Enterocrinin.
Answer:
Enterocrinin brings the release of enzymes from crypts of Leiberkuhn into intestinal juice.

Question 5.
Name some of the symbiotic bacteria residing in a healthy human colon. What is the role of this bacteria?
Answer:
Escherichia coli and streptococcus Faecalis, this synthesise vitamins B and K and convert bile pigment into brown pigments to impart colour to the farces; prevent the establishment of pathogenic microorganisms in the intestine.

Bile pigment contains water, mucin, lecithin, cholesterol, bile salts and bile pigments.

Question 6.
Define chemotrophs and heterotrophs?
Answer:
Organisms such as nitrifying bacteria e.g. Nitrosomonas and nitrobacteria, which capture the energy released during oxidation of inorganic chemical substances and prepare organic food with its help are called chemotrophs.

Organisms such as animal, fungi, some protestants (Trypanosoma) and any kind of bacteria which cannot utilize sun energy but use chemical bond energy in the form of organic molecules or food synthesized by other organisms in building up their own organic molecules are called Heterotro

Question 7.
How does the gastrovascular cavity in the cnidarian help in digestion?
Answer:
More organized animals, like cnidari&n (e.g. Hydra, Aurelia) have developed sac-like coelenteron or gastro Oscular cavity, which is lined by various types of endoderm cells. Gland, cells of the endoderm secrete their enzymes into the cavity and digest the food extracellularly. This kind of digestion outside cells within a cavity is extracellularly digestion. However in cnidarian, as soon as the food is, reduced to small fragments, the nutritive cells ingest them and complete the process of digestion intracellularly.

Question 8.
Crop, mid-gut-hepatic caeca, gizzard, buccal cavity, afraid gut- arrange these parts of the alimentary canal of a cockroach in proper sequence in relation to digestion.
Answer:
Buccal cavity, crop, gizzard, mid-gut, hepatic caeca, hindgut, are the parts of the alimentary canal of a cockroach.

Question 9.
Write down the human dental formula. What is meant by diphyodont?
Answer:

The dental formula (arrangement of teeth) of human is represented as.
1 2/2, C1/1 Pm2/2, M3/3. Thus, human teeth are dissimilar or heterodont.
Human teeth are diphyodont because milk teeth are replaced by permanent teeth in the adult.

Question 10.
What is the function of the oesophageal sphincter?
Answer:
A ring of muscle, the oesophageal sphincter, controls the opening of the oesophagus into the stomach.

Question 11.
What are microvilli? State their function.
Answer:
The finger-like projections produced by mucose, called villi. The cells that line the surface of the villi produce numerous microscopic .bristle like projections called the microvilli or brush border.

These cells mainly secrete mucus that acts as a lubricant and protects the epithelial surface from excoriation and digestion.

Question 12.
Name the cell which secretes mucus. What are the functions of mucus?
Answer:
Mucus is secreted by mucous or goblet cells.

Mucus acts as a lubricant and protects the epithelial surface from excoriation.

Question 13.
What are crypts of Leiberkuhn?
Answer:
The surface area of the gastrointestinal tract is lined by invaginations of the epithelium (pits) into the submucosa. These pits of the intestine are called the crypts of Leiberkuhn. These crypts contain specialized secretory cells.

Question 14.
Name three accessory digestive organs in a human.
Answer:

Tongue: It is located in the buccal cavity. Tongues are provided with gustatory receptors called taste buds.
Salivary glands: Humans have three pairs of salivary glands-parotid glands in the cheek, submandibular and sublingual, opening into the floor of the mouth.
Liver: It is situated in the right upper part of the abdomen. In an adult, the liver weighs about 1.5kg.

Question 15.
What is peristalsis how does it help in digestion?
Answer:
When food passes down into the oesophagus, a travelling wave of constrictions, which pushes the luminal contents downward is called peristalsis. Peristalsis is produced by the involuntary contraction of circular muscles. When a peristaltic wave reaches the end of the oesophagus the sphincter opens allowing the passage of bolus food to the stomach.

Question 16.
State the anatomical location of the pancreas.
Answer:
It is a soft, lobulated and elongated gland. It is the second-largest gland in the human body. It is located in the loop of the duodenum and extends up to the spleen behind the stomach. It consists of head, body and tail parts. It is a Heterocrine gland i.e. partly exocrine and partly endocrine.

The exocrine part consists of a large number of rounded glandular lobules. The endocrine part consists of a group of cells called islets of Langerhans formed of symbol cells. The alpha cells secrete glucagon hormone and symbol cells insulin hormone.

Digestion and Absorption Important Extra Questions Long Answer Type

Question 1.
What are the accessory digestive organs of a human digestive system?
Answer:
The human digestive system has many accessory organs, the tongue, which is located in the buccal cavity is a muscular organ with bony attachments with the floor of the buccal cavity. Tongues are provided with gustatory receptors called taste buds.

The accessory digestive glands include the salivary glands, the liver and the gall bladder and the pancreas. Humans have three pairs of salivary glands. Parotid glands in the cheek, submandibular and sublingual, opening into the floor of the mouth. The liver is situated in the right upper part of the abdomen. The gall bladder is a small end elongated muscular sac situated below the liver.

The pancreas is an elongated gland, situated near the junction of the stomach and the duodenum. Both the liver and pancreas act as endocrine and exocrine glands, whereas the gall bladder acts as a storing organ. The duct system of these organs is shown below diagram.

Question 2.
Discuss the five steps involved in the process of nutrition.

Digestive System
Answer:
Nutrition: Sum total of certain processes that enable a cell to utilize nutrients is called nutrition.

The entire process of nutrition includes the following steps: ingestion digestion, absorption, assimilation and egestion.
(a) Ingestion and Digestion: The process of taking in food through the mouth is called ingestion. The digestion of food starts from the mouth and ends in the intestines.
1. Mouth: The food is ingested through the mouth, carbohydrates, such as starch, are broken down or digested to form sugar. The saliva contains the enzyme salivary amylase that helps in the digestion of starch into sugar. The saliva also helps in lubricating the food and making it easier for swallowing. The tongue helps in rolling and pushing food into the oesophagus.

2. Oesophagus: TSie oesophagus or the food pipe helps in pushing the food into the stomach. The expansion and contraction of muscles of the oesophagus are called peristalsis or peristaltic movement.

3. Stomach: The stomach is a highly muscular organ. The gastric glands present in its walls secrete gastric juices and help in the digestion of food. These juices contain hydrochloric acid (HCI) and enzymes like pepsin. HCI created an acidic medium for the activation of enzymes and kills bacteria. These enzymes break down the proteins into smaller fragments called peptones. The muscles of the stomach help in churning the food so that it is properly mixed with the digestive juices.

4. Small intestine: The food moves from the stomach to the duodenum. Here emulsification of fat takes place with the help of the bile juice secreted by the liver. The bile juice is stored in the gall bladder. The pancreas secretes trypsin, amylase and lipase which are poured into the duodenum.

The food moves to the ileum, which is the lower part of the small intestine. The inner surface of the ileum contains thin finger-like projections called villi. Villi are responsible for the absorption of digested food. Blood then carries the absorbed food to a different part of the body and undigested food is pushed into the large intestine.

5. Large intestine: This part of the body absorbs water from the undigested food and solid waste is lubricated to form the faeces. The faeces pass on to the lower part of the large intestine, called the rectum, and thrown out of the body through the anus.

Question 3.
Where does the digestion of starch, proteins and fats take place and what is the role played by the associated glands?
Answer:
Starch: Digestion of starch takes place in the mouth. Carbohydrates are broken down or digested to form sugar. The saliva contains an enzyme salivary amylase that helps in the digestion of starch into sugar.

Proteins: The gastric glands present in the stomach secretes gastric juice which contains (HCI) hydrochloric acid and enzymes like pepsin. These enzymes breakdown the proteins into smaller fragments called peptones. Pepsin

Fat: Fat is digested in the duodenum (small intestine) with the help of the bile juice secreted by the liver. The bile juice is stored in the gall bladder. The pancreas secretes trypsin, amylase and lipase which are poured into the duodenum.