RBSE Solutions For Class 12 Biology Chapter 22: Digestive System of Human | Textbook Important Questions & Answers

RBSE Class 12 Biology Chapter – 22, Digestive System of Human, provides complete information related to the structure of alimentary canal, structure of teeth, process of digestion, digestive glands, functions of the liver, salivary glands and pancreas in the process of digestion, mechanism of the digestive system in humans and malnutrition. It also includes a detailed study about the mouth and the buccal cavity, stomach, small and large intestine, digestive enzymes, nutrition disorders and a lot more.

RBSE Solutions for Class 12 help students to perform their best in the exams. By practising these important questions, students can analyze their preparation, get a thorough knowledge about all the important terminologies, and at the same time, it helps them assess their understanding of the material.

The Rajasthan Board Class 12 Biology Chapter 12 important questions are the best study material for both class assignments and other board examinations. By practising these important questions, students can gain deep knowledge about the topics explained in this chapter and also help them to be well prepared for their upcoming examinations.

RBSE Class 12 Biology Chapter 22 Important Questions

RBSE Biology Chapter 22: MCQ Type Questions

Q.1. Which part secretes renin?

(a) Liver.

(b) Colon.

(c) Stomach.

(d) Rectum.

Sol: (c) Stomach.

Q.2. Which of the following statements are true about the Pancreatic juice?

(a) Pancreatic juice is acidic.

(b) Pancreatic juice is alkaline.

(c) Pancreatic juice is neutral.

(d) All of the above.

Sol: (b) Pancreatic juice is alkaline.

Q.3. Kupffer’s cells are found in ______________.

(a) Liver.

(b) Pancreas.

(c) Small intestine.

(d) Large intestine.

Sol: (a) Liver.

Q.4. Amylase enzyme acts on which substrate ______________.

(a) Protein.

(b) Carbohydrates.

(c) Fatty acids.

(d) Fat.

Sol: (b) Carbohydrates.

Q.5. Which of the following inactivates pepsinogen into active pepsin?

(a) Ptyalin.

(b) HCL.

(c) Bile.

(d) Renin.

Sol: (b) HCL.

Q.6. How many salivary glands are found in a man?

(a) 5 Pairs.

(b) 2 Pairs.

(c) 4 Pairs.

(d) 3 Pairs.

Sol: (d) 3 Pairs.

Q.7. Lier cells synthesize ______________.

(a) Bile juice.

(b) Trypsin.

(c) Amylopsin.

(d) Lipase.

Sol: (a) Bile juice.

Q.8. Where are the Islets of Langerhans found?

(a) Pancreas.

(b) Ileum.

(c) Colon.

(d) Liver.

Sol: (a) Pancreas.

Q.9. Which of the following vitamins helps in the maturation of red blood cells?

(a) Vitamin D.

(b) Vitamin A.

(c) Vitamin B12.

(d) Vitamin B.

Sol: (c) Vitamin B12.

Q.10. Which of the following parts of the alimentary canal bears villi?

(a) Stomach.

(b) Ileum.

(c) Oesophagus.

(d) Rectum.

Sol:(b) Ileum.

RBSE Biology Chapter 22: Short Answer Type Questions.

Q.1. Where is Kupffer’s cell found in the human body?

Sol. Kupffer’s cell is a specialized macrophage located in the liver. It is also known as the stellate macrophages or Kupffer–Borowicz cells.

Q.2. What is the role of Vitamin K?

Sol. In the human body, Vitamin K functions by clotting of blood during injuries or any wound and prevents excessive bleeding from the blood vessels.

Q.3. Which of the human organs is involved in synthesizing and storing glycogen?

Sol. Liver, the largest organ of the human body, is found on the right side of the belly, weighing around 2.5 to 3 pounds. This organ is involved in synthesizing and storing glycogen.

Q.4. What is the main cause for the deficiency of vitamin D in the body?

Sol. Calcium is the main source of vitamin D in the body. Lack of this mineral results in the deficiency of vitamin D followed by other nutrition deficiency disorders.

Q.5. Name the disease caused by protein deficiency.

Sol. Kwashiorkor is the deficiency disease caused by the high deficiency of protein in the diet. This type of deficiency disorder is mainly seen in infants and kids between the age group of 1 to 3 years.

Q.6. What is marasmus?

Sol. Marasmus disease is a nutritional deficiency disorder caused due to a severe deficiency of protein, vitamins, minerals, carbohydrates and lipids. It usually occurs in children and it can be life-threatening if not diagnosed at an early stage. Children, older adults, and people with a weak immune system are more prone to marasmus.

Q.7. Name the vitamin, which can be synthesized by our body cells?

Sol. Vitamin- D. It is the only vitamin, which our body cells can synthesize in the presence of sunlight, from a derivative of the steroid cholesterol present in the skin.

Q.8. What is the sphincter of Oddi?

Sol. The sphincter of Oddi is also called the Glisson’s sphincter of hepatopancreatic sphincter. It is the muscular valve, which functions by controlling the flow of digestive fluids into the stomach. The common bile duct opens into the duodenum. Its opening is regulated by a sphincter of Oddi.

Q.9. What is bolus?

Sol. The semisolid mass formed in the buccal cavity after the process of salivary digestion is called the bolus. The term bolus is generally applied to the mixture of food and the saliva solutions until they are passed to the stomach. Once the bolus reaches the stomach, it gets mixed with the gastric juices.

Q.10. What do you understand by Peyer’s patches?

Sol. The small patches or small masses of lymph glands found throughout the mucosa layer or the ileum region of the small intestine are called the Peyer’s patches. These patches are also known as aggregated lymphoid nodules,

Q.11. What is Brunner’s gland?

Sol. They are multicellular, compound tubular submucosal glands found in the submucosa region of the duodenum. They secrete digestive enzymes and mucus and are mainly involved in protecting the intestinal walls from gastric juices.

Q.12. What are the symptoms of marasmus?

Sol. The symptoms of marasmus are :

  1. Dizziness
  2. Weight loss.
  3. Dehydration.
  4. Lack of energy
  5. Stunted growth.
  6. Respiratory infections.

Q.13. What is emulsification?

Sol. Fats are found in large globules, which cannot be acted on by enzyme lipase. The bile salts found in the bile juice convert bigger fat globules into a smaller globule of 1μ diameter. This process is called emulsification. The emulsified fat can be easily acted upon the enzyme lipase.

Q.14. What are chylomicrons?

Sol. The cells of mucosa of ileum absorb fatty acids and glycerol in the presence of bile salts. These cells synthesize triglycerides and pack them in a small round packet. These small round packets are called the chylomicrons, whose diameter ranges from 1μ to 5μ.

Q.15. What are the symptoms of Kwashiorkor disease?

Sol. The common symptoms of Kwashiorkor disease are:

  1. Diarrhoea.
  2. Fatigue.
  3. Loss of weight.
  4. Failure to gain muscle mass.
  5. Compromised immune system.
  6. Swelling of the ankles, feet and belly.

Q.16.Where is the digested fat absorbed in the body?

Sol. The majority of fat digestion happens in the small intestine. The ileum is the organ, which absorbs the fat after the process of digestion. The ileum is the portion of the small intestine, located in between the jejunum and the caecum.

Q.17.What is Buccal Cavity?

Sol. The mouth is also called the buccal cavity or the oral cavity. The buccal cavity mainly comprises the primary organ of the digestive system including the teeth, tongue and salivary glands.

Q.18. What are the 4 types of teeth?

Sol. The four types of teeth are:

  1. Incisors.
  2. Canines.
  3. Premolars.
  4. Molars.

Q.19. What is malnutrition?

Sol. Malnutrition refers to the condition that results from eating in excess or an imbalanced diet. Protein-Energy Malnutrition is the most common form of malnutrition. Overall, malnutrition can be defined as the physical state of unbalanced nutrition.

Q.20.What is Kwashiorkor disease?

Sol. Kwashiorkor disease is a nutritional deficiency disorder caused due to severe protein deficiencies. This type of nutritional deficiency disorder is most common in rural areas, especially in the sub-Saharan regions and are mainly seen in infants and kids between the age group of 1 to 3 years.

RBSE Biology Class 12: Long Answer Type Questions

Q.1. Brief out the important functions of the liver.

Sol. The liver is the largest and important organ of the human body. Listed below are the important functions of the liver:

  1. It synthesizes blood clotting factors.
  2. It is responsible to activate the enzymes.
  3. It stores extra food in the form of glycogen.
  4. It stores vitamins, minerals and glycogen.
  5. It synthesizes urea by ornithine cycle.
  6. It also performs the detoxification of many toxins.
  7. It helps in detoxifying the blood and purifies it.
  8. It is responsible to excrete cholesterol, bilirubin, drugs and hormones.
  9. It is responsible to synthesize plasma proteins namely albumin and clotting factors.
  10. It produces and secretes bile juice, which helps in the digestion and absorption of fats, vitamins and cholesterol is produced in the liver.

Q.2. Describe the structure of an alimentary canal.

Sol. The alimentary canal is a simple tube-like structure present between the mouth and the anus, which exhibits many modifications to perform different functions. The alimentary canal originates from the embryonic ectoderm and endoderm. Its length is about 9 meters.

Organs of the Alimentary Canal

The main organs of the alimentary canal are:

The Mouth and Buccal cavity.

  1. It is a transverse slit-like structure.
  2. The mouth is guarded by a pair of lips, which are muscular and movable.
  3. The mouth opens into a buccal cavity.
  4. It is a cavity in the head region. Its dorsal side is made up of a palate, the ventral side is made up of a throat and both the lateral sides are made up of cheeks.
  5. The ventral side of the buccal cavity is occupied by a flat and muscular tongue.
  6. The tongue is a sensory, which bears four different types of taste buds- sour, salty, sweet and bitter tastes.

Functions of the tongue:

  1. It functions as a gusto-receptor.
  2. It helps in the mastication of the blood.
  3. It helps in the swallowing of the bolus.
  4. It acts as a brush to clean the teeth.
  5. In humans, it helps in speech.

The buccal cavity has upper and lower jaws, which comprises teeth. The arrangement of the teeth on the jaws are called dentition.

Salient features of teeth.

The mammalian teeth are codont. There are two sets of teeth:

Milk teeth – 20 numbers.

Permanent teeth – 32 numbers.

The mammalian teeth are of four different types:

  1. Incisors- four incisors in the upper jaw and four incisors in the lower jaw.
  2. Canines- Two canines in the upper jaw and two canines in the lower jaw.
  3. Premolars- Four premolars in the upper jaw and four premolars in the lower jaw.
  4. Molars- Six molars in the upper jaw and six in the lower jaw. It also includes four wisdom teeth.

Each tooth consists of a crown, a neck and a root.

Pharynx

It forms the common passage for food and air. The buccal cavity opens into the pharynx, which is comparatively less distinct in mammals.

Oesophagus.

It is a muscular tube through which small bolus of food passes from the mouth to the stomach. It is sharply bent at the point at which it meets the stomach. This prevents the backward movement of food from the stomach into it. Food in the digestive tract moves by an involuntary movement of alternate contraction and relaxation of muscles called peristalsis.

Stomach.

It is a muscular bag-like structure, which is situated in the anterior left parts of the abdominal cavity. which has three parts- cardiac part, fundus, and body.

  1. Cardiac part– It is so-called because it is present close to the heart. The opening of the oesophagus to the stomach is regulated by the cardiac sphincter.
  2. Fundus– It is a dome-shaped part of the stomach and is usually filled with air.
  3. Body– This is the main part of the stomach. The opening of the stomach into the small intestine is regulated by the pyloric sphincter.

Small intestine.

It is the longest part of the alimentary canal and comprises three parts:

  1. Duodenum– It is a C- shaped part of the small intestine, which receives the hepatopancreatic duct formed by the union of bile and pancreatic duct.
  2. Jejunum– Middle part of small intestine with thick walls and more vasculature.
  3. Ileum– The lower part of the small intestine with thin walls and less vasculature.

Large intestine.

The small intestine leads into the large intestine which has three parts- Caecum, Colon, and Rectum.

  1. Caecum– It is a small sac-like structure at the point where the small intestine meets the large intestine.
  2. Colon– It is divided into four regions- transverse colon, sigmoid colon ascending colon and descending colon.
  3. Rectum– It opens into the anus.

Q.3. Draw a neat labelled diagram of an alimentary canal.

Sol. Structure of Alimentary canal.Alimentary canal

Q.4. Explain in detail about the types of digestive glands.

Sol. Human alimentary canal is associated with three digestive glands.

Salivary glands.

The three pairs of salivary glands are found in the human body. Sublingual, submaxillary and parotid glands. Saliva secreted by these glands comes into the buccal cavity. Saliva is an alkaline fluid, which consists of water, Ptyalin or salivary amylase, lysozyme, mucous and ions of sodium chloride, potassium bicarbonate, etc. Ptyalin is the digestive enzyme and lysozyme functions by destroying bacteria.

Liver.

Liver, the largest digestive gland of the human body, found on the right side of the belly, weighing around 2.5 to 3 pounds. It is about 15 to 22 cm broad.This organ is involved in synthesizing and storing glycogen. It is derived from the embryonic endoderm.

Liver has two main lobes, the right lobe and the left lobe. Right lobe is larger than the left lobe. Besides these two lobes, the liver also consists of extra lobes which are known as quadrate and caudate lobes.Glisson’s capsule, a layer of fibrous tissue covers and provides external protection to the liver. This capsule is covered by peritoneum. This protects the liver from physical damage. It has two main sources of blood:

  1. Hepatic Portal Vein – This vein carries nutrient-rich blood from the digestive system,
  2. Hepatic Artery – This artery carries oxygenated blood from the heart.

Pancreas.

Pancreas is an abdominal organ located behind the stomach and surrounded by spleen, liver and small intestine. It is a vital part of the digestive system and is responsible for regulating blood sugar levels.

The pancreas functions by secreting various digestive enzymes, such as proteases, amylase and lipase into the duodenum. These enzymes help in digesting proteins, sugars and fat, respectively. Islets of Langerhans are embedded in the pancreas that secretes hormones such as insulin and glucagon into the blood.

Q.5. Brief out the functions of the liver with a neat labelled diagram.

Sol. The liver is a triangular, bilobed structure consisting of a larger right lobe and a smaller left lobe. It is the largest digestive gland of the human body.

Functions of Liver

The important functions of the liver are mentioned below:

  1. It is a storage site for Vitamin- A, D, E, K, and B12.
  2. It helps in the metabolization of fats, proteins and carbohydrates .
  3. It is also involved in synthesizing Vitamin- A, urea, prothrombin and fibrinogen.
  4. It is responsible for the absorption of vitamin K and functions as a clotting factor.
  5. Liver contains Kuffer cells involved in immune activity. These cells destroy any disease-causing agents.
  6. All the chemical substances including the hormones, alcohol ,minerals present in the blood are filtered by the liver.
  7. Bilirubin is formed by the breakdown of haemoglobin. The synthesized iron is stored in the liver to produce the new blood cells.
  8. It helps in the production of bile, which helps in the digestion and absorption of fats, vitamins and cholesterol produced in the liver.
  9. Synthesis of the Angiotensinogen hormone, which functions by narrowing of the blood vessels and prevents an increase in blood pressure.
  10. Albumin are produced by the liver, which transports fatty acids and steroids to maintain correct pressure and prevent leakage of blood vessels.

Structure of Liver.

Structure of Liver

Q.6. What are digestive enzymes? Explain in detail about the different types of digestive enzymes and their activities.

Sol. The enzymes, which function by breaking down polymeric macromolecules into smaller building blocks to facilitate their absorption by the body are called the digestive enzymes.

There are different types of enzymes, which are explained in detail in the table given below.

List of digestive enzymes and their activities.

Digestive enzymes. Activities. Products obtained.
ɑ-amylase. Starch. Maltose, Malto-triose and ɑ-limit dextrin.
Pepsin. Protein. Protease, Peptone poly-peptide.
Trypsin. Protein proteose, etc. Small poly-peptide.
Chymotrypsin. Protein proteose, etc. Tri-peptide, Di-peptide, small poly-peptide.
Carboxypeptidase. Small poly-peptides, Di-peptides. Tri-peptide, Di-peptide, Amino Acids.
Elastase. Elastin. Large, Small poly-peptide.
Lipase. Triglycerides. Fatty acids. Monoglyceride.
ɑ-amylase. Starch. Maltose, Maltotriose and ɑ-limit dextrin.
Nuclease. Nucleic Acid. Nucleotide.
Aminopeptidase, Dipeptidase, Maltase. Small poly-peptides,

Di-peptides,

Maltose and Maltotriose.

Aminoacids,

Dipeptide,

Two aminoacid and Glucose.

Lactase. Lactose. Glucose and Galactose.
Sucrase. Sucrose. Glucose and Fructose.
ɑ-limit dextrinase. ɑ-limit dextrin. Glucose.

Q.7. What are the different types of teeth? Explain with a neat labelled diagram.

Sol. The four different types of teeth are:

Incisors – They are located at the front of the mouth. There are eight incisors- four in the upper jaw and four in the lower jaw. They are involved in cutting the food particles into small and chewable pieces.

Canines – They are located at the corners of the dental arches. There are four canines- two in the upper jaw and two in the lower jaw. They are involved in tearing the food particles into small and chewable pieces.

Premolars – They are located behind the canines. There are eight premolars- four in the upper jaw and four in the lower jaw. They are involved in crushing and grinding food into smaller portions.

Molars – They are located at the back of the mouth. Molars are the largest and strongest teeth. There are twelve molars- six in the upper jaw and six in the lower jaw. They are well-adapted for grinding food into small and chewable pieces.

Structure and Different Types of Teeth.

Structure and Different Types of Teeth.

Q.8. What is the dental formula? Give the dental formula for the human being.

Sol. The method of expressing or describing the total number of teeth in man and animals according to the arrangement is termed as the Dental Formula.

The Dental Formula is expressed as:

Dental Formula = (2 incisors 1 canine 2 premolar and 3 molar) / (2 incisors 1 canine 2 premolar and 3 molar).

Humans have two dental formulae as they produce two different sets of teeth in their life cycle:

The primary dentition includes 20 teeth:

Incisors – 4/4 Canine – 2/2 Molar – 4/4 = 10 / 10 = 20.

The permanent dentition includes 32 teeth:

Eight incisors- four in the upper jaw and four in the lower jaw.

Four canines- two in the upper jaw and two in the lower jaw.

Eight premolars- four in the upper jaw and four in the lower jaw.

Twelve molars- six in the upper jaw and six in the lower jaw.

Therefore, the dental formulae of humans are given as:

I – 4/4 C – 2/2 P – 4/4 M – 6/6 = 16 / 16 = 32.

Where: I – Incisors, C- Canine and M-Molar.

Q.9. What are vitamins? Explain in detail about the different types of vitamins, their food sources, functions and their deficiency disorders.

Sol. Vitamins are organic compounds, found in natural foods, which are required for normal growth and maintenance of the body.

There are different types of vitamins , which are explained below in detail.

List of vitamins, food sources, functions and their deficiency disorders.

  • A Retinol

It is a fat soluble vitamin.

Food sources: Green vegetables, carrot, tomato, liver, egg yolk, milk, etc.

Functions: Formation of visual pigments.

Deficiency Disease. Night blindness and xerophthalmia (dry and itchy eyes.)

  • D Calciferol

It is a fat soluble vitamin.

Food sources: Fish, liver oil and milk, It is also synthesized by the skin in the presence of sunlight.

Functions: Absorption of Ca++ ion and bone formation.

Deficiency Disease: Rickets.

  • E Tocoferol.

It is a fat soluble vitamin.

Food sources: Green leaves, oil of germinating wheat, liver and milk.

Functions: Prevent oxidation of unsaturated fat.

Deficiency Disease: Infertility and Paralysis.

  • K-Naphthopquinone of Phylloquinone.

It is a fat soluble vitamin.

Food sources: Green leaves, also synthesized in the intestine by bacteria

Functions: Formation of prothrombin and formation of blood clot.

Deficiency Disease: Bleeding and unable to clot the blood.

  • B-Thiamine

It is a water soluble vitamin.

Food sources: Yeast cells, liver, milk, egg yolk,whole grains, etc.

Functions: Coenzyme and TTp formation

Deficiency Disease: Beriberi disease.

  • B2-Riboflavin.

It is a water soluble vitamin.

Food sources: Milk, egg yolk, yeast cells, liver, etc.

Functions: Involved in the growth and the part of FAD.

Deficiency Disease: Cheilosis- cracking in corners of mouth.

  • B3-Nicotinic acid

It is a water soluble vitamin.

Food sources: Whole grains, liver, milk, yeast cells, etc.

Functions: Part of the NAD and NADP

Deficiency Disease: Pellagra disease.

  • B5 – Pantothenic acid.

It is a water soluble vitamin.

Food sources: Yeast cells, etc.

Functions: Part of CoA

Deficiency Disease: Burning feet syndrome.

  • B6-Pyridoxine

It is a water soluble vitamin.

Food sources: Milk, vegetables, whole grains, yeast cells, etc.

Functions: Metabolism of fatty acids and amino acids.

Deficiency Disease: Dermatitis – A skin disorder.

  • B12 -Cyanocobalamin

It is a water soluble vitamin.

Food sources: Milk, liver, also synthesized in the intestine by bacteria.

Functions: Maturation of RBC- red blood cells.

Deficiency Disease:Pernicious anemia.

  • H-Biotin

It is a water soluble vitamin.

Food sources: Milk, liver, egg yolk, yeast cells, etc.

Functions: Metabolism of fatty acids.

Deficiency Disease: Hair fall and spectacle eye.

  • B9-Complex folic acid.

It is a water soluble vitamin.

Food sources: Green leafy vegetables, liver and yeast cells, etc.

Functions: Formation of RBC- Red Blood Corpuscles

Deficiency Disease: Macrocytic anemia.

  • C-Ascorbic acid.

It is a water soluble vitamin.

Food sources: Citrus fruits, tomatoes, gooseberry , etc.

Functions: Collagen synthesis and antioxidant

Deficiency Disease: Scurvy Disease, bleeding from the gums.

Q.10. What is malnutrition? Explain in detail about the nutritional deficiency disorders.

Sol.

Malnutrition

It refers to an incomplete or imbalanced diet. It is a type of a physical disorder of a person, which is mainly caused due to a diet which does not supply all the essential nutrients in adequate amount, which are required for the proper function of the cells and tissues.

Malnutrition makes a person weak, and more prone to various infectious diseases with poor immunity. Due to the malnutrition in infants, young children result in decreased growth and development and other nutritional deficiency disorders.

Based on the deficiency of the essential nutrients, malnutrition can be divided into four different types.

Undernutrition.

When the availability of food is insufficient for a longer period of time, then this condition is called under nutrition.

Over nutrition

When the availability of food is taken in more quantity for a longer period of time, then this condition is called over nutrition.

Imbalanced nutrition

Use of such a type of diet, which has only some nutrients in more ratio and others in a very less quantity, then this condition is called undernutrition.

Q.11. Write the difference between small intestine and large intestine.

Sol. Small intestine.

The small intestine is the part of the lower gastrointestinal tract, which is present just behind the stomach and acquires a maximum area of the abdominal cavity. It is a thin, long tube of about 10 feet long and found coiled, which consists of folds and ridges.

Large intestine.

The large intestine is present just beneath the stomach, found wrapping over the superior and lateral edges of the small intestine. It is a thick, long tube measuring around 5 feet in length.

Difference between small intestine and large intestine.

Small intestine Large intestine
It is a part of the digestive system. It is the terminal part of the intestine.
It is longer and narrower than the large intestine. It is shorter and wider than the small intestine.
Duodenum, ileum and jejunum are the components of the small intestine. Colon, cecum, rectum and anal canal are the components of the large intestine.
Involved in the process of digestion. Not involved in the process of digestion.
Composed of villi in the internal surface. Has a large number of goblet cells.
It is involved in the absorption of nutrients from the digested food. It is involved in the absorption of electrolytes and water and in the production of vitamins.

Q.12. What are the diseases caused by malnutrition?

Sol. Malnutrition can be defined as the lack of a balanced diet, which results in severe health related issues. Malnutrition refers to both deficiencies and excesses of intake of food. There are many deficiency disorders which are caused by the deficiency of vitamins, proteins, fats, carbohydrates, iron, and other minerals. These include: PEM- Protein-Protein-Energy Malnutrition, osteoporosis, etc.

According to the World Health Organization – WHO, there are five main diseases related to malnutrition. These includes:

Kwashiorkor

It is a nutritional deficiency disorder caused due to severe protein deficiencies in the diet. This type of nutritional deficiency disorder is most common in rural areas, especially in the sub-Saharan regions and are mainly seen in infants and kids between the age group of 1 to 3 years.

Marasmus

It is a nutritional deficiency caused due to a severe deficiency of protein and fats in the diet. It usually occurs in children and it can be life-threatening if not diagnosed at an early stage. Children, older adults, and people with a weak immune system are more prone to marasmus. It is also called the dry disease.

Exophthalmia.

It is a nutritional deficiency caused due to a severe deficiency of vitamin- A in the diet. It is the bulging of the eye anteriorly out of the orbit. This disorder is mainly related with the symptoms of eye irritation, dry eyes, pain in the eyes, blurred vision with sensitivity to light, shedding of tears, facing difficulties in moving eyes, etc.

Anemia.

It is a nutritional deficiency caused due to a severe deficiency of iron in the diet. It is the most common blood-related disorder, which affects 20 to 25 percent of the world’s population. As mentioned earlier, it is caused by the poor diet and deficiency of iron minerals in the body and the symptoms vary with the type of anemia. The common symptoms of anaemia include- Insomnia, jaundice, pica, pale skin, constipation, severe joint pains, fatigue and loss of energy, etc.

Goiter.

It is a nutritional deficiency caused due to a severe deficiency of iodine in the diet. In very rare cases, autoimmune disorders also lead to the cause of coiter. An individual with this nutritional deficiency disorder develops a lump in the neck, which is benign usually. Other common symptoms are difficulties in swallowing. In these conditions, other than the lump in the neck, patients do not show any symptoms.

Q.13. Define Assimilation and Egestion.

Sol. Assimilation

Assimilation is the process of obtaining energy from the absorbed food molecules. The absorbed food materials are transported to the cells through blood vessels. Here the food materials are decomposed to produce energy and are stored within the cells in the form of Adenosine Triphosphate – ATP molecules. The extra available amount of food is stored in the form of glycogen or fats. Liver plays an important role in the process of assimilation .

Q.14. What is Egestion?

Sol. Egestion

It is the process involving removing undigested waste products and food from the body of the organism. This process occurs after the process of digestion and the discharged materials include- undigested food and other toxic substances leftover from digestion. During the process of egestion, the remaining undigested parts of the food pass into the colon, which decomposes cellulose present in the undigested parts of the food with the help of the bacteria present in the colon. Later colon absorbs water, minerals, micose, dead epithelial cells, dead bacterial cells, bile pigments, and other undigested parts of the food, combines and forms feces. The formed feaces pases into the rectum and then the pressure is created and discharges the fecal matter out by the anus. Faeces are discharged once or twice in a 24 hours and are controlled by the nervous system.

Q.15. What is Digestion?

Sol. Digestion is the process of converting heavy food particles into smaller molecules for easy absorption by the bloodstream. This process occurs by breaking large, insoluble food molecules into smaller molecules, which involves the use of digestive fluids and enzymes such as bile, mucus, saliva, and hydrochloric acid.

There are four primary stages of food digestion in the human body that include:

  1. After the intake of food through the mouth, it makes its way through the stomach into the small intestine. The region where most digestion of food takes place.
  2. The nutrients from the digested food get absorbed into the bloodstream through small pores in the small intestine.
  3. The remaining undigested food is sent to the large intestine, where any unprocessed water or nutrients are reabsorbed into the body.
  4. The remaining waste food product and undigested parts of the food are passed out of the body in the form of stools.

We, at BYJU’S, aim to deliver students with all the necessary support and allow them to prove their abilities by excelling in their examination. Important Questions for RBSE Class 12 Biology Chapter- 22, Digestive System of Humans are prepared under the guidance of RBSE syllabus for Class 12 with proper structure and after thorough research on the particular topics.

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