Additional Questions - Chapter 5 Digestion and Absorption 11th Biology Zoology Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

Additional Questions & Answers
I. Multiple Choice Questions
Choose the correct Answer
Question 1.
Which of the following is the last phase of the process of digestion?
(a) ingestion
(b) assimilation
(c) eqestion
(d) digestion
Answer:
(c) eqestion
Question 2.
Which of the following teeth are the cutting teeth?
(a) incisors
(b) canines
(c) premolars
(d) molars
Answer:
(a) incisors
Question 3.
Plague formed on the teeth are mineral salts of
(a) sodium
(b) magnesium and manganese
(c) potassium
(d) calcium and magnesium
Answer:
(d) calcium and magnesium

Question 4.
Which muscle regulates the opening of oesophagus into the stomach?
(a) pyloric sphincter
(b) cardiac sphincter
(c) anal sphincter
(d) epiglottis
Answer:
(a) pyloric sphincter
Question 5.
The ' $\mathrm{V}$ ' shaped part of the small intestine is
(a) ileum
(b) jejunum
(c) duodenum
(d) colon
Answer:
(c) duodenum
Question 6. is the longest part of the small intestine
(a) lleum
(b) Jejunum
(c) Duodenum
(d) Rectum
Answer:
(a) lleum
Question 7.
Villi are concerned with
(a) secretion of enzymes
(b) secretion of mucus
(c) digestion of food
(d) absorption of digested food
Answer:
(d) absorption of digested food.

Question 8.
Peyer's patches produce
(a) monocytes
(b) lymphocytes
(c) basophils
(d) neutrophils
Answer:
(b) lymphocytes
Question 9.
Which of the following are non-functional in human beings?
(a) Small intestine
(b) Duodenum
(c) lleum
(d) Vermiform appendix
Answer:
(d) Vermiform Appendix
Question 10.
is formed of loose connective tissue containing nerves, blood, lymph vessels and sympathetic nerve fibres that control the secretions of intestinal juice.
(a) Serosa
(b) Sub-mucosa
(c) Mucosa
(d) Muscularis
(b) Sub-mucosa
Question 11

............... secrete $\mathrm{HCl}$ in the stomach.
(a) Peptic cells
(b) Goblet cells
(c) Oxyntic cells
(d) Zymogen cells
Answer:
(c) Oxyntic cells

Question 12.

.................... stores bile secreted by the liver.
(a) Pancreatic duct
(b) Duodenum
(c) Hepatic duct
(d) Gall bladder
Answer:
(d) Gall bladder
Question 13.
Detoxification is one of the functions of -
(a) small intestine
(b) liver
(c) pancreas
(d) stomach
Answer:
(b) liver
Question 14.
Which is the antibacterial agent present in the saliva?
(a) Ptyalin
(b) Mucus
(c) Lysozyme
(d) Bicarbonates
Answer:
(c) Lysozyme
Question 15.
Salivary amylase hydrolyses
(a) proteins
(b) carbohydrate
(c) fats
(d) vitamins
Answer:
(b) carbohydrate

Question 16.
Pepsin is a enzyme
(a) amylolytic
(b) lipolytic
(c) proteolytic
(d) proenzyme
Answer:
(c) proteolytic
Question 17.
Which enzyme acts on milk protein in infants in the presence of calcium ions?
(a) Pepsin
(b) Chymotrypsin
(c) Lipase
(d) Renin
Answer:
(d) Renin
Question 18.
Which is the active enzyme?
(a) Pepsinogen
(b) Trypsin
(c) Trypsinogen
(d) Chymotrypsinogen
Answer:
(b) Trypsin
Question 19.
What are the break down products of haemoglobin?
(a) Bile salts
(b) Bilirubin and biliverdin
(c) Phospholipids
(d) Cholesterol
Answer:
(d) Cholesterol

Question 20.
Which of the following does not contain any enzyme?
(a) Gastric juice
(b) Bile
(c) Pancreatic juice
(d) Succus entericus
Answer:
(b) Bile
Question 21.
Identify the odd one
(a) maltose
(b) lactose
(c) sucrose
(d) sucrase
Answer:
(d) sucrase
Question 22.
At the end of digestion, fats are converted into
(a) amino acids
(b) glycerol and fatty acids
(c) glucose
(d) galactose
Answer:
(b) glycerol and fatty acids
Question 23.
Protein coated fat globules are called
(a) micelles
(b) villi
(c) microvilli
(d) chylomicrons
Answer:
(d) chylomicrons

Question 24.
The calorific value of carbohydrates is
(a) 9.45
(b) 4.1
(c) 3.5
(d) 6.5
Answer:
(b) 4.1
Question 25.
Retaining feces in the rectum due to poor intake of fibre in the diet is called
(a) vomiting
(b) indigestion
(c) constipation
(d) diarrhoea
Answer:
(c) constipation
Question 26.
Which one of the following occurs due to reverse peristalsis?
(a) Vomiting
(b) Diarrhoea
(c) Constipation
(d) Indigestion
Answer:
(a) Vomiting
Question 27.
The failure of the liver to break down haemoglobin is called as
(a) gall stone
(b) jaundice
(c) appendicitis
(d) hernia
Answer:
(c) appendicitis

Question 28.
Degeneration and destruction of liver cells resulting in abnormal blood vessel and bile duct leading to the formation of fibrosis is known as
(a) gall stones
(b) jaundice
(c) hernia
(d) liver cirrhosis
Answer:
(d) liver cirrhosis
Question 29.
What causes obstruction in the cystic duct, hepatic duct and hepatopancreatic duct?
(a) Gall stones
(b) Jaundice
(c) Hernia
(d) Liver cirrhosis
Answer:
(a) Gall stones
Question 30.
Appendicitis is the inflammation of the
(a) caecum
(b) liver
(c) appendix
(d) rectum
Answer:
(c) appendix
Question 31.
Diarrhoea happens due to
(a) taking in of more volume of water
(b) defective liver
(c) inflammation of the appendix
(d) inability of colon to absorb fluid from the feces

Answer:
(d) inability of colon to absorb fluid from the feces
Question 32.
The erosion of the mucosa in the stomach or duodenum is referred to as
(a) stomach ache
(b) peptic ulcer
(c) duodenal cancer
(d) diarrhoea
Answer:
(b) peptic ulcer
Question 33.
The storage of excess of body fat in adipose tissue is
(a) peptic ulcer
(b) kwashiorkor
(c) jaundice
(d) obesity
Answer:
(d) obesity
II. Fill in the Blanks
Question 1.
Breakdown of macromolecules of food into micromolecules is ...............
Answer:
Digestion.
Question 2
The tearing teeth are called as ...............
Answer:
Canines
Question 3.
The deposition of calcium and magnesium salts on the teeth forms a hard layer called ..................

Answer:
Tartar/calculus/plaque.
Question 4.
The oral cavity leads into a short common passage for food and air called ......................
Answer:
Pharynx.
Question 5.
Two masses of lymphoid tissues called ........................ are located at the sides of the pharynx.
Answer:
Tonsils.
Question 6.
The opening of the stomach into the duodenum is guarded by the ............................. 
Answer:
Pyloric sphincter.
Question 7.
The inner wall of stomach has many folds called ........................... which unfolds to accommodate a large meal.
Answer:
Gastric rugae.
Question 8.
The wall of the duodenum has ............................ glands which secrete mucus and enzymes.
Answer:
Brunner's.
Question 9.
The ileal mucosa has numerous vascular projections called .......................
Answer:
Villi.
Question 10
...................... are the mucus secreting goblet cells and lymphoid tissue which produce lymphocytes.

Answer:
Peyer's patches.
Question 11.
The wall of the small intestine bears crypts between the base of the villi called ........................ 
Answer:
Crypts of Leiberkuhn.
Question 12.
Caecum and vermiform appendix are the important site for digestion in herbivores.
Answer:
Cellulose.
Question 13.
The dilations of colon are called ....................
Answer:
Haustra
Question 14.
The enlargement of anal column causes .................
Answer:
Piles / haemorrhoids
Question 15
....................... is the outermost layer of the wall of the alimentary canal.
Answer:
Serosa.
Question 16.
The enzyme secreting cells of gastric glands are called ....................... cells.
Answer:
Peptic or zymogen.
Question 17.
The cells secrete $\mathrm{HCl}$ in the stomach.

Answer:
Parietal or oxyntic.
Question 18.
The ................... is the largest gland in our body.
Answer:
Liver.
Question 19.
Each lobe of liver is covered by a thin connective tissue sheath called the ..................
Answer:
Glisson's capsule.
Question 20.
The detoxifies toxic substances.
Answer:
Liver.
Question 21.
The opening of the hepato-pancreatic duct into the duodenum is guarded by a sphincter called the sphincter of ..................
Answer:
Oddi.
Question 22
........................ gland is both exocrine and endocrine.
Answer:
Pancreas.
Question 23.
The successive waves of muscular contraction by which bolus passes down through the oesophagus is called ,.......................
Answer:
Peristalsis.

Question 24
...........................  activates pepsinogen.
Answer:
$\mathrm{HCl}$.
Question 25.
Renin converts caseinogen into casein is the presence of ions.
Answer:
Calcium.
Question 26
........................ activates trypsinogen.
Answer:
Enterokinase.
Question 27.
Trypsin hydrolyses proteins into polypeptides and........................... 
Answer:
Peptones.
Question 28.
......................... mucosa into the blood and lymph.
Answer:
Absorption.
Question 30.
The chylomicrons are transported into the within the intestinal villi.
Answer:
Lacteals.
Question 31.
Large intestine absorbs more amount of vitamins, some minerals and certain drugs.
Answer:
Water.

Question 32.
The eqestion of feces through the anal opening is called ......................
Answer:
Defecation
Question 33
.......................... are the major source of cellular fuel which provides energy.
Answer:
Carbohydrates.
Question 34
..................... are the best reserved food stored in our body.
Answer:
Lipids.
Question 35.
Marasmus is the ........................... deficiency disease.
Answer:
Protein.
Question 36
......................... is the digestive disorder in which the food is not properly digested leading to a feeling of fullness of stomach.
Answer:
Indigestion.
Question 37
......................... is caused due to hepatitis viral infection.
Answer:
Jaundice.
Question 38.
The crystallized cholesterol in the bile forms ......................
Answer:
Gall stones.

Question 39
..................... is a structural abnormality in which superior part of the stomach protrudes slightly
Answer:
Hiatus hernia.
Question 40.
Treatment for diarrhoea is known as ................. therapy.
Answer:
Oral hydration.
Question 41
.......................... refers to an eroded area of the tissue lining in the stomach or duodenum.
Answer:
Peptic ulcer.
Question 42.
Ulcer is mostly due to infection caused by the bacterium .....................
Answer
Helicobacter pylori.
Question 43
....................... is caused due to the storage of excess of body fat in adipose tissue.
Answer:
Obesity.
III. Answer the following Questions
Question 1.
What are the uses of food?
Answer:
The food we eat provides energy and organic substances for growth and the replacement of worn out and damaged tissues. It regulates and coordinates the various activities that take place in the body.
Question 2.
What are the components of food?

Answer:
The components of food are carbohydrates, proteins, lipids, vitamins, minerals, fibre and water.
Question 3.
Why do we need a digestive system?
Answer:
The food that we eat are macromolecules, and inabsorbable. These are to be broken down . into smaller micro-molecules in absorbable forms. This is done by digestive system.
Question 4.
Why do plants not require a digestive system?
Answer:
Plants are autotrophs. They prepare their own food using $\mathrm{CO}_2, \mathrm{H}_2 \mathrm{O}$ in the presence of sunlight trapped by the chlorophyll pigment present in the leaves. There is no need of digestive system for plants as they use the starch as such.
Question 5.
What is the function of the digestive system?
Answer:
The function of the digestive system is to bring the nutrients, water and electrolytes from the external environment into every cell in the body through the circulatory system.
Question 6.
Define:
(a) Ingestion : The taking in of food is called ingestion.
(b) Digestion : The break down of the macromolecules into micromolecules by the action of digestive enzymes is called digestion.
(c) Absorption : The taking in of digested food materials into the blood stream is called absorption.
(d) Assimilation : The conversion of absorbed food materials into components of cells is called assimilation.
(e) Egestion : The elimination of the undigested substances from the body is called egestion.

Question 7.
What is thecodont dentition?
Answer:
Every tooth in human beings is embedded in a socket in the jaw bone. This type of attachment is called the codont dentition.
Question 8.
What is diphyodont dentition?
Answer:
Human beings and many mammals form two sets of teeth during their life time, a set of 20 temporary milk teeth which gets replaced by a set of 32 permanent teeth. This type of dentition is called diphyodont dentition.
Question 9.
What is heterodont dentition?
Answer:
Human beings have four different types of teeth namely incisors, canines, premolars and molars. This is known as heterodont dentition.
Question 10.
What is known as the dental formula of human beings?
Answer:
The arrangement of teeth in each half of the upper and lower jaw in the order of I, C, P and $\mathrm{M}$ can be represented by the dental formula. The dental formula of man is $2123 / 2123$.
Question 11.
What is gingivitis?
Answer:
Mineral salts like calcium and magnesium are deposited on the teeth and form a hard layer of 'tartar' or calculus called plaque. If the plaque formed on teeth is not removed regularly, it would spread down the tooth into the narrow gap between the gums and enamel and causes inflammation, called gingivitis, which leads to redness and bleeding of the gums and to bad smell.
Question 12.

What is enamel?

Answer:
The hard chewing surface of the teeth is made of enamel and helps in mastication of food.
Question 13.
What is the function of tongue?
Answer:
Tongue helps in intake of food, chew and mix food with saliva, to swallow food and also to speak. The upper surface of the tongue has small projections called papillae with taste buds.
Question 14.
What is the function of the cardiac sphincter?
Answer:
A cardiac sphincter or gastro esophageal sphincter regulates the opening of oesophagus into the stomach.
Question 15.
What is gastro oesophagus reflex disorder?
Answer:
If the cardiac sphincter does not contract properly during the churning action of the stomach the gastric juice with acid may flow back into the oesophagus and cause heart bum, resulting in GERD (Gastro Oesophagus Reflex Disorder).
Question 16.
What is the function of the pyloric sphincter?
Answer:
The opening of the stomach into the duodenum is guarded by the pyloric sphincter. It periodically allows partially digested food to enter the duodenum and also prevents regurgitation of food.
Question 17.
What are gastric rugae?
Answer:
The inner wall of stomach has many folds called gastric rugae which unfolds to accommodate a large meal.

Question 18.
Write a short note on the small intestine.
Answer:
The small intestine assists in the final digestion and absorption of food. It is the longest part of the alimentary canal and has three regions, a ' $\mathrm{U}$ ' shaped duodenum ( $25 \mathrm{~cm}$ long), a long coiled middle portion jejunum ( $2.4 \mathrm{~m}$ long) and a highly coiled ileum ( $3.5 \mathrm{~m}$ long).

The wall of the duodenum has Brunner's glands which secrete mucus and enzymes. lleum is the longest part of the small intestine and opens into the caecum of the large intestine.

The ileal mucosa has numerous vascular projections called villi which are involved in the process of absorption and the cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance that increase the surface area enormously.
Along with Villi, the ileal mucosa also contain mucus secreting goblet cells and lymphoid tissue known as Peyer's patches which produce lymphocytes. The wall of the small intestine bears crypts between the base of villi called crypts of Leiberkuhn.
The colon is lined by dilations called haustra (singular - haustrum) (Figure). The "S" shaped sigmoid colon (pelvic colon) opens into the rectum. Rectum is concerned with temporary storage of feces. The rectum open out through the anus. The anus is guarded by two anal sphincter muscles. The anal mucosa is folded into several vertical folds and contains arteries and veins called anal columns. Anal column may get enlarged and causes piles or haemorrhoids.
Explain the structure of the large intestine.
Answer:
The large intestine consists of caecum, colon and rectum. The caecum is a small blind pouch like structure that opens into the colon and it possesses a narrow finger like tubular projection called vermiform appendix.

Both caecum and vermiform appendix are large in herbivorous animal and act as an important site for cellulose digestion with the help of symbiotic bacteria. The colon is divided into four regions - an ascending, a transverse, a descending part and a sigmoid colon.

The colon is lined by dilations called haustra (singular - haustrum) (Figure). The "S" shaped sigmoid colon (pelvic colon) opens into the rectum. Rectum is concerned with temporary storage of feces. The rectum open out through the anus. The anus is guarded by two anal sphincter muscles. The anal mucosa is folded into several vertical folds and contains arteries and veins called anal columns. Anal column may get enlarged and causes piles or haemorrhoids.
Question 20.
Explain the internal structure of the gut.
Answer:
The wall of the alimentary canal from oesophagus to rectum consists of four layers (Figure) namely serosa, muscularis, sub-mucosa and mucosa. The serosa (visceral peritoneum) is the outermost layer and is made up of thin squamous epithelium with some connective tissues. Muscularis is made of smooth circular and longitudinal muscle fibres with a network of nerve cells and parasympathetic nerve fibres which controls peristalsis.

The submucosal layer is formed of loose connective tissue containing nerves, blood, lymph vessels and the sympathetic nerve fibres that control the secretions of intestinal juice. The innermost layer lining the lumen of the alimentary canal is the mucosa which secretes mucous.
Question 21.
Explain the salivary glands.
Answer:
There are three pairs of salivary glands in the mouth. They are the largest parotids gland in the cheeks, the sub-maxillary sub-mandibular in the lower jaw and the sublingual beneath the tongue. These glands have ducts such as Stenson's duct, Wharton's duct and Bartholin's duct or duct of Rivinis respectively (Figure). The salivary juice secreted by the salivary glands reaches the mouth through these ducts. The daily secretion of saliva from salivary glands ranges from 1000 to $1500 \mathrm{~mL}$.

Question 22.
Write a short note on gastric glands.
Answer:
The wall of the stomach is lined by gastric glands. Chief cells or peptic cells or zymogen cells in the gastric glands secrete gastric enzymes and Goblet cells secrete mucus. The Parietal or oxyntic cells secrete $\mathrm{HCl}$ and an intrinsic factor responsible for the absorption of Vitamin $B_{12}$ called Castle's intrinsic factor.
Question 23.
Explain the structure of liver.
Answer:
The liver, the largest gland in our body, is situated in the upper right side of the abdominal cavity, just below the diaphragm. The liver consists of two major left and right lobes; and two minor lobes. These lobes are connected with diaphragm. Each lobe has many hepatic lobules (functional unit of liver) and is covered by a thin connective tissue sheath called the Glisson's capsule. 

Liver cells (hepatic cells) secrete bile which is stored and concentrated in a thin muscular sac called the gall bladder. The duct of gall bladder (cystic duct) along with the hepatic duct from the liver forms the common bile duct.
The bile duct passes downwards and joins with the main pancreatic duct to form a common duct called hepato-pancreatic duct. The opening of the hepato-pancreatic duct into the duodenum is guarded by a sphincter called the sphincter of Oddi (Figure). Liver has high power of regeneration and liver cells are replaced by new ones every $3-4$ weeks.
Question 24.
Write the functions of liver.
Answer:
Apart from bile secretion, the liver also performs several functions.
- Destroys aging and defective blood cells.
- Stores glucose in the form of glycogen or disperses glucose into the blood stream with the help of
- pancreatic hormones.
- Stores fat soluble vitamins and iron.
- Detoxifies toxic substances.
- Involves in the synthesis of non-essential amino acids and urea.
Question 25.
Write on the secretions of the pancreas.
Answer:
The second largest gland in the digestive system is the Pancreas, which is a yellow coloured, compound elongated organ consisting of exocrine and endocrine cells. It is situated between the limbs of the ' $U$ ' shaped duodenum.

The exocrine portion secretes pancreatic juice containing enzymes such as pancreatic amylase, trypsin and pancreatic lipase and the endocrine part called Islets of Langerhans secretes hormones such as insulin and glucagon. The pancreatic duct directly opens into the duodenum.
Question 26.
Explain the digestion in the buccal cavity.
Answer:
The smell, sight and taste as well as the mechanical stimulation of food in the mouth, triggers a reflex action which results in the secretion of saliva. The mechanical digestion starts in the mouth by grinding and chewing of food. It is called mastication.

The saliva contain water, electrolytes $\left(\mathrm{Na}^{+}, \mathrm{K}^{+}, \mathrm{CL}^{-}\right.$and $\left.\mathrm{HCO}_3\right)$, salivary amylase (ptyalin), antibacterial agent lysozyme and a lubricating agent mucus (a glycoprotein). The mucus in saliva prepares the food for swallowing by moistening, softening, lubricating and adhering the masticated food into a bolus.
About 30 percent of polysaccharide, starch is hydrolyzed by the salivary amylase enzyme into disaccharides (maltose). The bolus is then passed into the pharynx and then into the oesophagus by swallowing or deglutition. The
bolus further passes down through the oesophagus to the stomach by successive waves of muscular contraction called peristalsis. The gastro oesphageal sphincter controls the passage of food into the stomach.
Question 27.
Explain the digestion in the stomach.

Answer:
Food remains in the stomach for 4 to 5 hours, the rhythmic peristaltic movement chums and mixes the food with gastric juice and make it into a creamy liquid called chyme. The gastric secretion is partly controlled by autonomic reflexes.

The secretion of gastric juice begins when the food is in the mouth. The gastric juice contains $\mathrm{HCl}$ and proenzymes. The proenzyme pepsinogen, on exposure to $\mathrm{HCl}$ gets converted into the active enzyme pepsin which converts proteins into proteoses and peptones (peptides).

The $\mathrm{HCl}$ provides an acidic medium ( $\mathrm{pH}$ 1.8) which is optimum for pepsin, kills bacteria and other harmful organisms and avoids putrifaction. The mucus and bicarbonates present in the gastric juice play an important role in lubrication and protection of the mucosal epithelium from the eroding nature of the highly acidic $\mathrm{HCl}$ (Figure). Another proteolytic enzyme found in gastric juice of infants is renin which helps in the digestion of milk protein, caseinogen to casein in the presence of calcium ions. This enzyme secretion gradually reduces with aging.
Question 28.
Explain the digestion in the small intestine.
Answer:
The bile, pancreatic juice and intestinal juice are the secretions released into the small intestine. Movements generated by the muscularis layer of the small intestine helps in the thorough mixing of the food with various secretions in the intestine and thereby facilitate digestion.
The pancreatic juice contains enzymes such as trypsinogen, chymotrypsinogen, carboxypeptidases, pancreatic amalyses, pancreatic lipases and nucleases. Trypsinogen is activated by an enzyme, enterokinase, secreted by the intestinal mucosa into active trypsin, which in turn activates the enzyme chymotrypsinogen in the pancreatic juice.
The bile contains bile pigments (bilirubin and biliverdin) as the break down products of hemoglobin of dead RBCs, bile salts, cholesterol and phospholipids but has no enzymes. Bile helps in emulsification of fats. Bile salts reduce the surface tension of fat droplets and break them into small globules. Bile also activates lipases to digest lipids.

Proteins and partially digested proteins in the chyme on reaching the intestine are acted upon by the proteolytic enzymes of pancreatic juice. Trypsin hydrolyses proteins into polypeptides and peptones, while chymotrypsin hydrolyses peptide bonds associated with specific amino acids. The pancreatic amylase converts glycogen and starch into maltose.

Lipase acts on emulsified fat (triglycerides) and hydrolyses them into free fatty acid and monoglycerides. Monoglycerides are further hydrolysed to fatty acid and glycerol. Nucleases in the pancreatic juice break the nucleic acid into nucleotides and nucleosides.
The secretions of the Brunner's gland along with the secretions of the intestinal glands constitute the intestinal juice or succus entericus. The enzymes in the intestinal juice such as maltase, lactase, sucrase (invertase), dipeptidases, lipases, nucleosidases act on the breakdown products of bile and pancreatic digestion.
The mucus along with the bicarbonate ions from the pancreas provides an alkaline medium $(\mathrm{pH}$ 7.8) for the enzymatic action. As a result of digestion, all macromolecules of food are converted into their corresponding monomeric units.
Question 29.
Explain the process of absorption of the digested food.
Answer:
Absorption is a process by which the end product of digestion passes through the intestinal mucosa into the blood and lymph. The villi in the lumen of ileum are the absorbing units, consisting of a lacteal duct in the middle surrounded by fine network of blood capillaries. The process of absorption involves active, passive and facilitated transport.

Small amounts of glucose, amino acids and electrolytes like chloride ions are generally absorbed by simple diffusion. The passage of these substances into the blood depends upon concentration gradients. However, some of the substances like fructose are absorbed with the help of the carrier ions like $\mathrm{Na}^{+}$.
This mechanism is called facilitated transport. Nutrients like amino acids, glucose and electrolytes like $\mathrm{Na}^{+}$are absorbed into the blood against the concentration gradient by active transport. The insoluble substances like fatty acids, glycerol and fat soluble vitamins are first incorporated into small, spherical water soluble droplets called micelles and are absorbed into the intestinal mucosa where they are re-synthesized into protein coated fat globules called chylomicrons which are then transported into the lacteals within the intestinal villi and eventually empty into lymphatic duct.

The lymphatic ducts ultimately release the absorbed substances into the blood stream. While the fatty acids are absorbed by the lymph duct, other materials are absorbed either actively or passively by the capillaries of the villi (Figure). Water soluble vitamins are absorbed by simple diffusion or active transport.
Transport of water depends upon the osmotic gradient. Absorption of substances in the alimentary canal takes place in mouth, stomach, small intestine and large intestine.
However maximum absorption takes place in the small intestine. Absorption of simple sugars, alcohol and medicines takes place in the stomach. Certain drugs are absorbed by blood capillaries in the lower side of the tongue and mucosa of mouth. Large intestine is also involved in absorption of more amounts of water, vitamins, some minerals and certain drugs.
Question 30.
Write a note on assimilation.
Answer:
Absorbed substances are transported through blood and lymph to the liver through the hepatic portal system. From the liver, nutrients are transported to all other regions of the body for utilization. All the body tissues utilize the absorbed substance for their activities and incorporate into their protoplasm, this process is called assimilation.
Question 31.
Write a paragraph on egestion.
Answer:
The digestive waste and unabsorbed substances in the ileum enter into the 

large intestine and it mostly contains fibre called roughage. The roughage is utilized by symbiotic bacteria in the large intestine for the production of substances like vitamin $\mathrm{K}$ and other metabolites. All these substances are absorbed in the colon along with water.

The waste is then solidified into fecal matter in the rectum. The fecal matter initiates a neural reflex causing an urge or desire for its removal. The egestion of feces through the anal opening is called defecation. It is a voluntary process and is carried out by a peristaltic movement.
Question 32.
Write on carbohydrates and lipids.
Answer:
Carbohydrates are sugar and starch. These are the major source of cellular fuel
which provides energy. The caloric value of carbohydrate is 4.1 calories per gram and its physiological fuel value is $4 \mathrm{Kcal}$ per gram. Lipids are fats and derivatives of fats, are also the best reserved food stored in our body which is used for production of energy. Fat has a caloric value of $9.45 \mathrm{Kcal}$ and a physiological fuel value of $9 \mathrm{Kcal}$ per gram.
Question 33.
Write a paragraph on proteins.
Answer:
Proteins are source of amino acids required for growth and repair of body cells. They are stored in the body only to a certain extent; large quantities are excreted as nitrogenous waste. The caloric value and physiological fuel value of one gram of protein are $5.65 \mathrm{Kcal}$ and $4 \mathrm{Kcal}$ respectively. According to ICMR (Indian Council of Medical Research) and WHO (World Health 

Organization), the daily requirement of protein for an average Indian is $1 \mathrm{gm}$ per $1 \mathrm{~kg}$ body weight.
Question 34.
Explain the protein deficiency diseases.
Answer:
Growing children require more amount of protein for their growth and development. Protein deficient diet during early stage of children may lead to protein energy malnutrition such as Marasmus and Kwashiorkor. Symptoms are dry skin, pot-belly, oedema in the legs and face, stunted growth, changes in hair colour, weakness and irritability.

Marasmus is an acute form of protein malnutrition. This condition is due to a diet with inadequate carbohydrate and protein. Such children are suffer from diarrhoea, body becomes lean and weak (emaciated) with reduced fat and muscle tissue with thin and folded skin.
Question 35.
What is indigestion?
Answer:
It is a digestive disorder in which the food is not properly digested leading to
a feeling of fullness of stomach. It may be due to inadequate enzyme secretion, anxiety, food poisoning, over eating and spicy food.
Question 36.
What is constipation?
Answer:

In this condition, the feces are retained within the rectum because of irregular bowel movement due to poor intake of fibre in the diet and lack of physical activities.
Question 37.
What is vomiting?
Answer:
It is reverse peristalsis. Harmful substances and contaminated food from stomach are ejected through the mouth. This action is controlled by the vomit center located in the medulla oblongata. A feeling of nausea precedes vomiting.
Question 38.
Write a short note on jaundice.
Answer:
It is the condition in which liver is affected and the defective liver fails to break down haemoglobin and to remove bile pigments from the blood. Deposition of these pigments changes the colour of eye and skin yellow. Sometimes, jaundice is caused due to hepatitis viral infections.
Question 39.
Write a short note on liver cirrhosis.
Answer:
Chronic disease of liver results in degeneration and destruction of liver cells resulting in abnormal blood vessel and bile duct leading to the formation of fibrosis. It is also called deserted liver or scarred liver. It is caused due to infection, consumption of poison, malnutrition and alcoholism.
Question 40.
Write a short note on gall stones.
Answer:

Any alteration in the composition of the bile can cause the formation of stones in the gall bladder. The stones are mostly formed of crystallized cholesterol in the bile. The gall stone causes obstruction in the cystic duct, hepatic duct and also hepato-pancreatic duct causing pain, jaundice and pancreatitis.
Question 41.
What is appendicitis?
Answer:
It is the inflammation of the vermiform appendix, leading to severe abdominal pain. The treatment involves the removal of appendix by surgery. If treatment is delayed the appendix may rupture and results in infection of the abdomen, called peritonitis.
Question 42.
What is hiatus hernia or diaphragmatic hernia?
Answer:
It is a structural abnormality in which superior part of the stomach protrudes slightly above the diaphragm. The exact cause of hiatus hernias is not known. In some people, injury or other damage may weaken muscle tissue, by applying too much pressure (repeatedly) on the muscles around the stomach while coughing, vomiting, and straining during bowel movement and lifting heavy object.

Heart bum is also common in those with a hiatus hernia. In this condition, stomach contents travel back into the oesophagus or even into oral cavity and causes pain in the center of the chest due to the eroding nature of acidity.
Question 43.
Write a short note on diarrhoea.
Answer:
It is the most common gastrointestinal disorder worldwide. It is sometimes caused by bacteria or viral infections through food or water. When the colon is infected, the lining of the intestine is damaged by the pathogens, thereby the colon is unable to absorb fluid.

The abnormal frequency of bowel movement and increased liquidity of the fecal discharge is known as diarrhoea. Unless the condition is treated,

dehydration can occur. Treatment is known as oral hydration therapy. This involves drinking plenty of fluids - sipping small amounts of water at a time to rehydrate the body.
Question 44.
Write a paragraph on peptic ulcer.
Answer:
It refers to an eroded area of the tissue lining (mucosa) in the stomach or duodenum. Duodenal ulcer occurs in people in the age group of $25-45$ years. Gastric ulcer is more common in persons above the age of 50 years. Ulcer is mostly due to infections caused by the bacterium Helicobacter pylori. It may also be caused due to uncontrolled usage of aspirin or certain antiinflammatory drugs. Ulcer may also be caused due to smoking, alcohol, caffeine and psychological stress.
Question 45.
What is obesity?
Answer:
It is caused due to the storage of excess of body fat in adipose tissue. It may induce hypertension, atherosclerotic heart disease and diabetes. Obesity may be genetic or due to excess intake of food, endocrine and metabolic disorders.
Question 46.
Write a note on BMI.
Answer:
Degree of obesity is assessed by body mass index (BMI). A normal BMI range for adult is $19-25$; above 25 is considered as obese. BMI is calculated as body weight in $\mathrm{Kg}$, divided by the square of body height in meters. For example, a $50 \mathrm{Kg}$ person with a height of $160 \mathrm{cms}$ would have a BMI of 19.5.
That is $\mathrm{BMI}=50 / 1.62=19.5$