Maharashtra Board Class 11 Biology Chapter 14 Human Nutrition Solutions

Biology Class 11 Chapter 14 Exercise Solutions

1. Choose Correct Option

Question A. Acinar cells are present in ............
(a) liver
(b) pancreas
(c) gastric glands
(d) intestinal glands
Answer: (b) pancreas
In simple words: Acinar cells are specialized cells found in the pancreas that are responsible for producing and secreting digestive enzymes.

🎯 Exam Tip: Remember the specific location and function of acinar cells as they are key to pancreatic exocrine activity and frequently asked in MCQs.

Question B. Which type of teeth are maximum in number in human buccal cavity?
(a) Incisors
(b) Canines
(c) Premolars
(d) Molars
Answer: (d) Molars
In simple words: In adults, molars are the most numerous type of teeth, primarily used for grinding food.

🎯 Exam Tip: Familiarize yourself with the different types of human teeth (incisors, canines, premolars, molars) and their typical numbers and functions for dental formula questions.

Question C. Select odd one out on the basis of digestive functions of tongue.
(a) Taste
(b) Swallowing
(c) Talking
(d) Mixing of saliva in food
Answer: (c) Talking
In simple words: While the tongue is essential for talking, tasting, swallowing, and mixing food with saliva, talking is not a direct digestive function.

🎯 Exam Tip: When identifying odd one out, focus on the primary physiological role related to the given context. The tongue's roles in digestion are taste, food manipulation, and initiation of swallowing.

Question D. Complete the analogy: Ptyalin: Amylase : : Pepsin : ............
(a) Lipase
(b) Galactose
(c) Proenzyme
(d) Protease
Answer: (d) Protease
In simple words: Ptyalin is another name for salivary amylase, which digests carbohydrates; similarly, pepsin is a protease, an enzyme that digests proteins.

🎯 Exam Tip: Understand enzyme classifications. Amylases digest carbohydrates, proteases digest proteins, and lipases digest fats. This is a fundamental concept for digestive biology.

2. Answer The Following Questions

Question A. For the school athletic meet, Shriya was advised to consume either Glucon-D or fruit juice but no sugarcane juice. Why it must be so?
Answer: Sugarcane juice contain disaccharides. Disaccharides take time to digest i.e. breaking into monosaccharides, Glucon - D and fruit juices contain monosaccharide. Therefore, for instant supply of energy during athletic meet Glucon - D or fruit juices are preferred and not sugarcane.
In simple words: Glucon-D and fruit juices provide readily available monosaccharides for quick energy, while sugarcane juice contains disaccharides that require more time to break down before energy can be released.

🎯 Exam Tip: Distinguish between monosaccharides and disaccharides in terms of their absorption rate. Monosaccharides are absorbed directly, providing quick energy, which is crucial for athletic performance.

Question B. Alcoholic people may suffer from liver disorder. Do you agree? Explain your answer.
Answer:
1. Liver disorder in alcoholic people may occur after years of heavy drinking.
2. Most of the alcohol in the body is broken down in the liver by an enzyme called alcohol dehydrogenase, which transforms ethanol into a toxic compound called acetaldehyde (CH3CHO).
3. Over consumption of alcohol leads to cirrhosis (distorted or scarred liver) and eventually to liver failure.
Therefore, alcoholic people may suffer from liver disorder.
In simple words: Yes, alcoholic people often suffer from liver disorders because the liver metabolizes alcohol, producing toxic substances that can damage liver cells over time, leading to conditions like cirrhosis and ultimately liver failure.

🎯 Exam Tip: Focus on the liver's role in detoxification and the specific compounds (ethanol, acetaldehyde) involved in alcohol metabolism to explain liver damage effectively.

Question C. Digestive action of pepsin comes to a stop when food reaches small intestine. Justify.
Answer: Pepsin acts in acidic medium thus it is active in stomach. There is alkaline condition in the small intestine. pH of small intestine is very high for pepsin to work. Therefore, pepsin gets denatured in the small intestine.
In simple words: Pepsin functions optimally in the highly acidic environment of the stomach; when food enters the alkaline environment of the small intestine, pepsin becomes denatured and inactive, stopping its digestive action.

🎯 Exam Tip: Emphasize the importance of optimal pH for enzyme activity. Pepsin's denaturation in the small intestine's alkaline pH is a classic example of enzyme specificity to environmental conditions.

Question D. Small intestine is very long and coiled. Even if we jump and run, why it does not get twisted? What can happen if it gets twisted?
Answer:
1. Mesentery is a tissue that is located in the abdomen. It attaches the small intestine to the wall of the abdomen and keeps it in place and therefore it does not get twisted while running and jumping.
2. If small intestine gets twisted, the affected spot may block the food, liquid passing through it. It may sometimes cut off the blood flow if the twist is very severe. If this happens the surrounding tissue may die and can cause serious problems.
In simple words: The mesentery, a tissue that anchors the small intestine to the abdominal wall, prevents it from twisting during movement; if it does twist, it can block digestion and blood flow, leading to severe complications.

🎯 Exam Tip: Highlight the structural role of the mesentery. Also, be prepared to describe the physiological consequences of intestinal obstruction or torsion, such as compromised blood supply and tissue necrosis.

3. Write Down The Explanation

Question A. Digestive enzymes are secreted at appropriate time in our body. How does it happen?
Answer:
1. The digestive enzymes and juices are produced in sequential manner and at a proper time.
2. These secretions are under neurohormonal control.
3. Sight, smell and even thought of food trigger saliva secretion.
4. Tenth cranial nerve stimulates secretion of gastric juice in stomach.
5. Even the hormone gastrin brings about the same effect.
In simple words: Digestive enzymes are secreted at specific times through a coordinated neurohormonal control system, where sensory inputs like sight or smell and hormones like gastrin regulate the production and release of digestive juices.

🎯 Exam Tip: Focus on the nervous (e.g., vagus nerve, sight/smell) and hormonal (e.g., gastrin) mechanisms that regulate digestive secretions, as this demonstrates a complex physiological control system.

Question B. Explain the structure of tooth. Explain why human dentition is considered as thecodont, diphydont and heterodont.
Answer:
1. Structure of tooth:
• A tooth consists of the portion that projects above the gum called crown and the root that is made up of two or three projections which are embedded in gum.
• A short neck connects the crown with the root.
• The crown is covered by the hardest substance of the body called enamel which is made up of calcium phosphate and calcium carbonate.
• Basic shape of tooth is derived from dentin which is a calcified connective tissue.
• The dentin encloses the pulp cavity. It is filled with connective tissue pulp. It contains blood vessels and nerves.
• Pulp cavity has extension in the root of the tooth called root canal.
• The dentin of the root of tooth is covered by cementurn which is a bone like substance that attaches the root to the surrounding socket in the gum.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक दाँत की आंतरिक संरचना को दर्शाता है, जिसमें बाहरी परत (एनैमल), उसके नीचे की डेंटिन, पल्प कैविटी (लुगदी गुहा), मसूड़े, हड्डी, रूट कैनाल (जड़ नहर), और नसें तथा रक्त वाहिकाएँ शामिल हैं। यह विभिन्न भागों की स्थिति और उनके संबंधों को स्पष्ट करता है।
2. Human dentition is described as thecodont, diphyodont and heterodont.
3. It is called thecodont type because each tooth is fixed in a separate socket present in the jaw bones by gomphosis type of joint.
4. It is called diphyodont type because we get only two sets of teeth, milk teeth and permanent teeth.
5. It is called heterodont type because humans have four different type of teeth like incisors, canines, premolars and molars.
In simple words: A tooth comprises a crown, neck, and root, with layers of enamel, dentin, and pulp. Human dentition is thecodont because teeth are fixed in sockets, diphyodont as there are two sets of teeth (milk and permanent), and heterodont due to the presence of four different tooth types (incisors, canines, premolars, molars).

🎯 Exam Tip: When describing tooth structure, include key components like enamel, dentin, and pulp cavity. For dentition types, clearly define thecodont, diphyodont, and heterodont with examples relevant to human anatomy.

Question C. Explain heterocrine nature of pancreas with the help of histological structure.
Answer:
Pancreas:
1. Pancreas is a leaf shaped heterocrine gland present in the gap formed by bend of duodenum under the stomach.
2. Exocrine part of pancreas is made up of acini, the acinar cells secrete alkaline pancreatic juice that contains various digestive enzymes.
3. Pancreatic juice is collected and carried to duodenum by pancreatic duct.
4. The common bile duct joins pancreatic duct to form hepato-pancreatic duct. It opens into duodenum.
5. Opening of hepato-pancreatic duct is guarded by sphincter of Oddi.
6. Endocrine part of pancreas is made up of islets of Langerhans situated between the acini.
7. It contains three types of cells a-cells which secrete glucagon, P-cells which secretes insulin and δ cells secrete somatostatin hormone.
8. Glucagon and insulin together control the blood-sugar level.
9. Somatostatin hormone inhibits glucagon and insulin secretion.
In simple words: The pancreas is a heterocrine gland, meaning it has both exocrine and endocrine functions; its exocrine part (acini) produces digestive enzymes, while its endocrine part (islets of Langerhans) secretes hormones like insulin and glucagon that regulate blood sugar.

🎯 Exam Tip: Clearly differentiate between the exocrine and endocrine functions of the pancreas. Mentioning both acini for enzymes and islets of Langerhans (with alpha, beta, and delta cells) for hormones demonstrates a comprehensive understanding.

4. Write Short Note On

Question A. Position and function of salivary glands.
Answer:
Salivary Glands:
• There are three pairs of salivary glands which open in buccal cavity.
• Parotid glands are present in front of the ear.
• The submandibular glands are present below the lower jaw.
• The glands present below the tongue are called sublingual.
• Salivary glands are made up of two types of cells.
• Serous cells secrete a fluid containing digestive enzyme called salivary amylase.
• Mucous cells produce mucus that lubricates food and helps swallowing.
In simple words: Salivary glands, including parotid, submandibular, and sublingual pairs, are located in the buccal cavity region and produce saliva containing salivary amylase for starch digestion and mucus for lubrication, aiding in swallowing.

🎯 Exam Tip: List the three major pairs of salivary glands and their locations. For functions, focus on the roles of salivary amylase (carbohydrate digestion) and mucus (lubrication) in the initial stages of digestion.

Question B. Jaundice
Answer:
1. Jaundice is a disorder characterized by yellowness of conjunctiva of eyes and skin and whitish stool.
2. It is a sign of abnormal bilirubin metabolism and excretion.
3. Jaundice develops if excessive break down of red blood cells takes place along with increased bilirubin level than the liver can handle or there is obstruction in the flow of bile from liver to duodenum.
4. Bilirubin produced from breakdown of haemoglobin is either water soluble or fat soluble.
5. Fat soluble bilirubin is toxic to brain cells.
6. There is no specific treatment to jaundice.
7. Supportive care, proper rest are the treatments given to the patient.
In simple words: Jaundice is a condition causing yellowing of skin and eyes due to an accumulation of bilirubin, a pigment from red blood cell breakdown, often indicating issues with the liver's ability to process or excrete bilirubin, or a bile duct obstruction.

🎯 Exam Tip: Define jaundice by its primary symptom (yellowing) and underlying cause (bilirubin accumulation). Explain the three main mechanisms: excessive RBC breakdown, impaired liver function, or bile duct obstruction.

Question 5. Observe the diagram. This is histological structure of stomach. Identify and comment on significance of the layer marked by arrow.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र पेट की ऊतक संरचना को दर्शाता है, जिसमें एक विशेष परत को तीर से चिह्नित किया गया है। यह परत पेट की आंतरिक दीवार का एक हिस्सा है, जो पाचन तंत्र में इसके कार्य को समझने के लिए महत्वपूर्ण है।
Answer: The layer marked in the diagram represents glandular epithelium of mucosa. Significance of the glandular epiihelium of mucosa: Goblet cells of the epithelial layer of a mucous membrane secrete mucus which lubricates the lumen of the alimentary canal. This helps in movement of food through the gastrointestinal tract.
In simple words: The arrow points to the glandular epithelium of the mucosa in the stomach, which contains goblet cells that secrete mucus to lubricate the alimentary canal, aiding food movement.

🎯 Exam Tip: When analyzing histological diagrams, identify the layers (mucosa, submucosa, muscularis, serosa) and their specific cell types and secretions. Emphasize the protective and lubricating role of mucus in the digestive tract.

Question 6. Find out pH maxima for salivary amylase, trypsin, nucleotidase and pepsin and place on the given pH scale
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Answer:
Salivary amylase = 6.8
Trypsin = 8
Nucleotidase = 7.5
Pepsin = 2
In simple words: Different digestive enzymes have distinct optimal pH ranges for their activity: pepsin works in acidic conditions (pH 2), salivary amylase near neutral (pH 6.8), nucleotidase slightly alkaline (pH 7.5), and trypsin in alkaline conditions (pH 8).

🎯 Exam Tip: This question tests your knowledge of enzyme kinetics and optimal pH. Remember that enzymes are highly sensitive to pH, and deviation from the optimum can lead to denaturation and loss of function.

Question 7. Write the name of a protein deficiency disorder and write symptoms of it.
Answer:
1. Kwashiorkor is a protein deficiency disorder.
2. This protein deficiency disorder is found generally in children between one to three years of age.
3. Children suffering from Kwashiorkor are underweight and show stunted growth, poor brain development, loss of appetite, anaemia, protruding belly, slender legs, bulging eye, oedema of lower legs and face, change in skin and hair colour.
In simple words: Kwashiorkor is a protein deficiency disorder common in young children, characterized by symptoms such as stunted growth, poor brain development, oedema, a protruding belly, and changes in skin and hair.

🎯 Exam Tip: Be able to identify Kwashiorkor as a protein deficiency disorder. Crucially, list several distinct symptoms, particularly growth failure, edema, and changes in appearance, as these are key diagnostic features.

Question 8. Observe the diagram given below label the A, B, C, D, E and write the function of A, C in detail.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र मानव पाचन तंत्र के अंगों - यकृत, पित्ताशय, पेट और अग्न्याशय - को दर्शाता है, जिसमें विभिन्न भागों को A, B, C, D, E अक्षरों से चिह्नित किया गया है। यह इन अंगों की शारीरिक स्थिति को स्पष्ट करता है।
Answer:
A- Bile duct, B- Stomach, C- Common hepatic duct, D- Pancreas, E- Gall Riadder
Functions: Bile duct: It carries bile from the gall bladder and empties it into the upper part of the small intestine. Common hepatic duct: It drains bile from the liver. It helps in transportation of waste from liver and helps in digestion by releasing bile.
In simple words: The diagram labels A as the Bile duct (carrying bile from the gallbladder to the small intestine) and C as the Common hepatic duct (draining bile from the liver, aiding digestion and waste transport).

🎯 Exam Tip: Correctly identify the labeled parts in anatomical diagrams. For functions, focus on the roles of bile ducts in bile transport, which is essential for fat emulsification and waste excretion.

Practical / Project: Here Are The Events In The Process Of Digestion. Fill In The Blanks And Complete The Flow Chart.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र पाचन प्रक्रिया में होने वाली घटनाओं का एक प्रवाह चार्ट है, जिसमें भोजन के विभिन्न चरणों और पाचन एंजाइमों की भूमिका को दर्शाया गया है। इसमें मुंह से लेकर बड़ी आंत तक भोजन के मार्ग और उसके रासायनिक परिवर्तनों को विस्तार से समझाया गया है।
Answer: The completed flow chart detailing the events in the process of digestion is as follows:
Mouth: Teeth (Function: mechanical digestion), Tongue (Function: taste, swallowing, mixing of saliva).
Salivary glands: secrete saliva (Pairs – parotid, submandibular, sublingual; Water Function: moisten food; Mucin Function: lubrication; Salivary amylase Function: carbohydrate digestion).
Oesophagus: function – transport bolus.
Stomach: Acidic medium, Churning. Gastric juice (HCL: Function – kill microbes, activate pepsinogen; Pepsinogen \( \implies \) Pepsin; Pepsin Function: protein digestion; Mucus Function: protection).
Duodenum: Alkaline medium.
Pancreatic Juice contains: Trypsinogen \( \implies \) Trypsin; Chymotrypsinogen \( \implies \) Chymotrypsin; Pancreatic amylase, Pancreatic lipase, Nucleases.
Bile Juice contains: Bile pigments, Bile salts (Function: emulsification of fats).
Intestinal Juice contains: Enterokinase \( \implies \) Chymotrypsin; Intestinal Lipase, Maltase, Sucrase, Lactase.
Digestion processes: Starch \( \implies \) Maltose (Salivary amylase).
Proteins, Proteoses, Peptones \( \implies \) Polypeptides (Trypsin, Chymotrypsin).
Dipeptides \( \implies \) Amino acids (Dipeptidase).
Lipids \( \implies \) Emulsified fats (Bile salts) \( \implies \) Fatty acids + Monoglycerides (Pancreatic/Intestinal Lipase).
Carbohydrates: Glycogen/Starch \( \implies \) Disaccharides (Pancreatic amylase). Maltose \( \implies \) Glucose (Maltase). Sucrose \( \implies \) Glucose + Fructose (Sucrase). Lactose \( \implies \) Glucose + Galactose (Lactase).
Nucleic acids \( \implies \) Nucleotides (Nucleases) \( \implies \) Nucleosides + Phosphate (Nucleotidases) \( \implies \) Sugar + base (Nucleosidases).
Chyle: undergoes Absorption in Jejunum, Ileum (Intestinal Villi).
Unabsorbed Food: Faeces \( \implies \) Egestion in Large intestine \( \implies \) Anus (Assimilation).
In simple words: The flow chart illustrates the journey of food through the digestive system, showing how different enzymes and digestive juices break down complex food substances into simpler forms at various stages, from the mouth to the small intestine, for absorption, with blanks filled to complete the process.

🎯 Exam Tip: For flow charts, focus on the sequential order of events, the specific enzymes involved at each stage, and the end products of digestion for carbohydrates, proteins, and fats. Pay attention to the organs where each step occurs.

Can You Recall? (Textbook Page No. 161)

Question 1. What is nutrition?
Answer:
1. Nutrition is the sum of the processes by which an organism consumes and utilizes food substances,
2. WHO defines nutrition as the intake of food, considered in relation to the body's dietary needs.
3. The term nutrition includes the process like ingestion, digestion, absorption, assimilation and egestion.
In simple words: Nutrition encompasses all the processes by which an organism takes in, digests, absorbs, assimilates, and utilizes food for growth, energy, and maintenance.

🎯 Exam Tip: Provide a comprehensive definition of nutrition, including the key stages: ingestion, digestion, absorption, assimilation, and egestion, to show a complete understanding of the metabolic process.

Question 2. Enlist life processes that provide us energy to perform different activities.
Answer: The life processes which are essential and provide us energy are nutrition and respiration.
In simple words: The primary life processes that supply energy for our activities are nutrition (obtaining and processing food) and respiration (releasing energy from processed food).

🎯 Exam Tip: Identify nutrition and respiration as the two fundamental processes for energy generation. Briefly explain how each contributes to the body's energy requirements.

Think About It (Textbook Page No. 161)

Question 1. Our diet includes all necessary nutrients. Still we need to digest it. Why is it so?
Answer:
1. Digestion is a very important process of converting complex, noil-diffusible and non-absorbable food substances into simple, diffusible and assimilable substances.
2. Our diet includes all necessary nutrients, which are in the form of complex substances like carbohydrates, proteins, fats and vitamins.
3. These complex substances are converted into simple, diffusible and assimilable substances through the process of digestion.
Hence, there is a need for digestion of food.
In simple words: We need to digest food even if it contains all nutrients because nutrients in their natural form are complex and non-absorbable; digestion breaks them down into simpler, absorbable forms that the body can utilize.

🎯 Exam Tip: Explain that digestion is crucial for converting complex macromolecules into simpler micromolecules that can be absorbed by the body. Emphasize the concepts of diffusibility and assimilability.

Human Digestive System (Textbook Page No. 161)

Question 1. Label the diagram

ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक सुस्पष्ट नामांकित चित्र है जो मानव पाचन तंत्र और उससे संबंधित ग्रंथियों को शरीर में उनकी वास्तविक स्थिति में दर्शाता है। इसमें मौखिक गुहा, ग्रसनी, अन्नप्रणाली, यकृत, पित्ताशय, अग्न्याशय, पेट, छोटी आंत (ग्रहणी, जेजुनम, इलियम) और बड़ी आंत (अनुप्रस्थ कोलन, आरोही कोलन, अवरोही कोलन, सीकम, वर्मीफॉर्म अपेंडिक्स, मलाशय और गुदा) जैसे प्रमुख अंग शामिल हैं।
In simple words: This diagram is a labeled illustration of the human digestive system, showing the major organs such as the oral cavity, pharynx, esophagus, liver, stomach, pancreas, small intestine, and large intestine, along with associated glands, in their anatomical positions.

🎯 Exam Tip: When presented with a diagram to label, ensure accurate identification of all major organs and glands of the digestive system. Understanding their relative positions is key to describing the path of food.

Do You Know? (Textbook Page No. 162)

Question 1. Who controls the deglutition?
Answer: The process of swallowing is called deglutition. Medulla oblongata controls the deglutition.
In simple words: Deglutition, or swallowing, is primarily controlled by the medulla oblongata in the brainstem.

🎯 Exam Tip: Remember that deglutition is a complex reflex involving both voluntary and involuntary phases. The medulla oblongata is a key control center for many vital involuntary functions, including swallowing.

Question 2. Is deglutition voluntary or involuntary?
Answer:
• Deglutition consists of three phases: oral phase, pharyngeal phase and oesophagal phase.
• The oral phase is voluntary whereas the pharyngeal and oesophagal phases are involuntary.
In simple words: Deglutition starts with a voluntary oral phase where food is moved into the pharynx, followed by involuntary pharyngeal and esophageal phases that propel food towards the stomach.

🎯 Exam Tip: Clearly delineate the three phases of deglutition and identify which are voluntary and which are involuntary. This highlights the coordinated neural control involved in swallowing.

Use Your Brain Power (Textbook Page No. 165)

Question 1. Draw a neat labelled diagram of human alimentary canal and associated glands in situ.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक सुस्पष्ट नामांकित चित्र है जो मानव पाचन तंत्र और उससे संबंधित ग्रंथियों को शरीर में उनकी वास्तविक स्थिति में दर्शाता है। इसमें मौखिक गुहा, ग्रसनी, अन्नप्रणाली, यकृत, पित्ताशय, अग्न्याशय, पेट, छोटी आंत (ग्रहणी, जेजुनम, इलियम) और बड़ी आंत (अनुप्रस्थ कोलन, आरोही कोलन, अवरोही कोलन, सीकम, वर्मीफॉर्म अपेंडिक्स, मलाशय और गुदा) जैसे प्रमुख अंग शामिल हैं।
In simple words: This is a clearly labeled diagram illustrating the human alimentary canal and its associated glands in their natural positions within the body. It includes key organs like the oral cavity, pharynx, esophagus, stomach, liver, pancreas, small intestine (duodenum, jejunum, ileum), and large intestine (cecum, colon, rectum, anus).

🎯 Exam Tip: When drawing, focus on anatomical accuracy and neat labeling of all components, including the accessory digestive glands (salivary glands, liver, pancreas, gallbladder) and their connections to the alimentary canal.

Question 2. Write a note on human dentition.
Answer:
1. Human dentition is described as thecodont, diphyodont and heterodont.
2. It is called thecodont type because each tooth is fixed in a separate socket present in the jaw bones by gomphosis type of joint.
3. It is called diphyodont type because we get only two sets of teeth, milk teeth and permanent teeth.
4. It is called heterodont type because humans have four different type of teeth like incisors, canines, premolars and molars.
In simple words: Human dentition is characterized as thecodont (teeth embedded in jaw sockets), diphyodont (two sets of teeth throughout life: milk and permanent), and heterodont (four distinct types of teeth: incisors, canines, premolars, and molars, each with specialized functions).

🎯 Exam Tip: Ensure precise definitions for the terms thecodont, diphyodont, and heterodont, providing clear explanations for each characteristic of human dentition. These terms are fundamental to understanding dental anatomy.

Question 3. Muscularis layer in stomach is thicker than that in intestine. Why is it so?
Answer: Muscularis layer in stomach is thicker than that of intestine because food is churned and gastric juices are mixed in the stomach whereas in intestine only absorption takes place.
In simple words: The stomach's muscularis layer is thicker than the intestine's because it performs vigorous churning and mixing of food with gastric juices, while the intestine's primary role is absorption, requiring less muscular force.

🎯 Exam Tip: Relate the thickness of the muscularis layer to the specific mechanical functions of each organ. The stomach's robust muscle layers are adapted for mechanical digestion, whereas the intestine's thinner layers facilitate peristalsis and absorption.

Question 4. Liver is a vital organ. Justify.
Answer:
1. Kupffer cells of liver destroy toxic substances, dead and worn-out blood cells and microorganisms.
2. Bile juice secreted by liver emulsifies fats and makes food alkaline.
3. Liver stores excess of glucose in the form of glycogen.
4. Deamination of excess amino acids to ammonia and its further conversion to urea takes place in liver.
5. Synthesis of vitamins A, D, K and BI2 takes place in liver.
6. It also produces blood proteins like prothrombin and fibrinogen.
7. During early development, it acts as haemopoietic organ.
Therefore, liver is a vital organ.
In simple words: The liver is a vital organ due to its numerous essential functions, including detoxification by Kupffer cells, fat emulsification by bile, glucose storage as glycogen, amino acid deamination into urea, synthesis of various vitamins and blood proteins, and its role in blood cell formation during development.

🎯 Exam Tip: When justifying the liver's vitality, list multiple diverse functions such as metabolic regulation (glucose, amino acids, fats), detoxification, synthesis of essential substances (vitamins, proteins), and its role in immune defense and early hematopoiesis.

Internet My Friend: (Textbook Page No. 171)

Question 1. Collect the different videos of functioning of digestive system,
Answer:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक QR कोड है जिसे स्कैन करके छात्र पाचन तंत्र के कार्यप्रणाली से संबंधित विभिन्न वीडियो देख सकते हैं और अवधारणात्मक स्पष्टता प्राप्त कर सकते हैं।
In simple words: Students can use the provided QR code to access educational videos illustrating the complex functioning of the human digestive system, enhancing their conceptual understanding.

🎯 Exam Tip: Active engagement with multimedia resources can significantly improve understanding of complex biological processes. Utilize such tools for visual learning and conceptual clarity beyond textbook readings.

Find Out (Textbook Page No. 162)

Question 1. What will be the dental formula of a three years old child?
Answer: The dental formula of a three-year-old child will be: I \( \frac{2}{2} \), C \( \frac{1}{1} \), M \( \frac{2}{2} \) = \( \frac{2,1,2}{2,1,2} \)
i. e. 5 x 2 = 10 teeth in each jaw = 20 teeth.
As a child has 20 teeth by the age of three.
In simple words: A three-year-old child has a primary (deciduous) dental formula of I \( \frac{2}{2} \) C \( \frac{1}{1} \) M \( \frac{2}{2} \), meaning 2 incisors, 1 canine, and 2 molars in each quadrant, totaling 20 teeth.

🎯 Exam Tip: Remember that primary dentition (milk teeth) lacks premolars. Practice writing dental formulas for both deciduous and permanent dentition, understanding what each number represents for incisors, canines, premolars, and molars.

Internet My Friend (Textbook Page No. 162)

Question 1.Find out the role of orthodontist and dental technician.
Answer:a. Orthodontics is a specialization in dental profession. Orthodontist straightens the crooked teeth, locates problem in patients' teeth and their overall oral development. They might use X-rays, plaster molds or dental appliances like retainers and space maintainers to correct the problems,
b. Dental technicians are the ones which improves patients' appearance, ability to chew and speech. They make dentures, crowns, bridges and dental braces.
In simple words: Orthodontists specialize in correcting tooth and jaw alignment, while dental technicians create prosthetic devices like braces and dentures that orthodontists use.

🎯 Exam Tip: Understanding the roles of dental professionals like orthodontists and technicians is important for questions on career paths or specialized dental care.

Question 2.What is a root canal treatment?
Answer:- Root canal treatment is also known as endodontic treatment. - It is a dental treatment of removing infection from inside of a tooth. - Root canal is hollow section of tooth which contains the nerve tissue, blood vessels and other cells, this is also known as pulps. - Crown and root are a part of tooth. Crown is present above the gum while root is embedded in the gum. e. Pulp which is present inside the root canal nourishes the tooth and provides moisture to the surrounding material. - The nerves present inside the pulp sense hot cold temperatures as pain. - First step of a root canal treatment is removal of dead pulp tissues by making a hole on the surface of tooth. - In second step, the dentist cleans and decontaminates the area and fills the hollow area with adhesive cement in order to seal the canal completely. - The tooth is dead after the therapy and the patient no longer feel any pain but the tooth becomes more fragile than ever. - The last step of root canal is adding a crown or filling. Until the crown or filling is complete, patient is not supposed to chew or bite using that tooth. After the crown or filling patient can use that tooth as before.
In simple words: Root canal treatment removes infected pulp from inside a tooth to save it, cleans the area, and then fills it, often followed by a crown to restore function.

🎯 Exam Tip: For descriptive questions, list the key steps and components involved in the procedure, such as pulp, crown, root canal, and the treatment phases.

Find Out (Textbook Page No. 163)

Question 1.You must have heard about appendicitis. It is inflammation of appendix. Find more information about this disorder.
Answer:1. Appendicitis is a condition where there is inflammation of appendix. 2. Appendix is a vestigial organ. It is a finger shaped pouch that projects from colon on the lower right side of the abdomen. 3. Appendicitis pain is very severe. It initially starts from the navel and then moves. 4. It occurs in the people of age group between 10 to 30. 5. Surgical removal is the standard treatment for appendicitis. 6. Symptoms: Nausea and vomiting, loss of appetite, low grade fever, constipation, abdominal bloating, severe pain in the right side of the abdomen. 7. Appendicitis is caused when there is blockage in the lining of the appendix that results in infection. The bacteria multiply rapidly and causes inflammation and it is then filled with pus. 8. If not treated properly appendix can rupture which can lead to further complications.
In simple words: Appendicitis is the inflammation of the appendix, a finger-shaped organ, causing severe abdominal pain and often requiring surgical removal to prevent rupture and further complications.

🎯 Exam Tip: Focus on the definition, common symptoms, causes, and standard treatment (surgical removal) when describing appendicitis.

Question 2.What is heartburn? Why do we take antacids to control it?
Answer:Heart burn is a problem created when stomach contents (acid) are forced back up to oesophagus. It causes a burning pain in lower chest. Antacids are bases and help to treat heartburn by neutralizing the stomach acid. The key ingredients of antacids are calcium carbonate, magnesium hydroxide, aluminium hydroxide or sodium bicarbonate.
In simple words: Heartburn occurs when stomach acid flows back into the esophagus, causing a burning sensation, and antacids are used to neutralize this acid due to their basic chemical composition.

🎯 Exam Tip: When explaining heartburn, highlight the reflux of stomach acid and the role of antacids as bases in neutralizing it for a complete answer.

Activity (Textbook Page No. 163)

Question 1.Make a model of human digestive system in a group.
Answer:[Students are expected to perform this activity on their own.]
In simple words: This is a practical group activity where students create a physical representation of the human digestive system.

🎯 Exam Tip: For activity-based questions, simply state that it's a practical task for students to engage in hands-on learning.

Always Remember (Textbook Page No. 166)

Question 1.Food remains for a very short time in mouth but action of salivary amylase continues for further IS to 30 minutes till gastric juice mixes with food in the stomach. Why do you think it stops after the food gets mixed with gastric juice?
Answer:1. The gastric juices are mixed with food in the stomach. 2. The pH of the stomach is 1.0-2.0 which is very acidic. Such high level of acidity leads to denaturation of salivary amylase's protein structure. 3. On the other hand, pH 6.8 is required for salivary amylase to carry out the activity which is not found in stomach. Thus, activity of salivary amylase is stopped when food is mixed with gastric juice.
In simple words: Salivary amylase stops working in the stomach because the highly acidic environment (pH 1.0-2.0) denatures its protein structure, rendering it inactive, as it requires a near-neutral pH (6.8) to function.

🎯 Exam Tip: Emphasize the concept of enzyme specificity for pH and how the drastic pH change in the stomach denatures salivary amylase.

Internet My Friend (Textbook Page No. 167)

Question 1.How are bile pigments formed?
Answer:1. When old and worn out red blood cells are destroyed by macrophages in liver, the globin portion of hemoglobin is split off and heme is converted to biliverdin. 2. Most of this biliverdin is converted to bilirubin, which gives bile its major pigmentation.
In simple words: Bile pigments like biliverdin and bilirubin are formed in the liver from the breakdown of old red blood cells, specifically from the heme component of hemoglobin.

🎯 Exam Tip: Key points for this answer are the breakdown of old red blood cells, hemoglobin, heme, and the conversion to biliverdin and then bilirubin.

Think About It (Textbook Page No. 167)

Question 1.How can I keep my pancreas healthy? Can a person live without pancreas?
Answer:1. Pancreas can be kept healthy by: - Eating proper balanced and low-fat diet, with plenty of whole grains, fruits and vegetables. - Regular exercise and maintaining a healthy weight. - Limiting alcohol consumption and avoid smoking. - Adequate intake of water. - Regular checkups. 2. The pancreas is a gland that secretes digestive enzymes and insulin which is needed for a person to survive. 3. Without pancreas the person will develop diabetes and will have to take insulin for the rest of the life. 4. Without pancreas the body's ability to absorb nutrients also decreases. Hence, though a person can survive without pancreas he may have to remain dependent on the medicines for survival.
In simple words: A healthy pancreas is maintained through a balanced diet, exercise, and avoiding alcohol/smoking. While a person can live without a pancreas, it requires lifelong insulin dependency for diabetes and medical support for nutrient absorption.

🎯 Exam Tip: When answering, differentiate between lifestyle recommendations for pancreas health and the medical implications and dependencies if the pancreas is absent.

Do It Yourself? (Textbook Page No. 167)

Question 1.You have studied the representation of enzymatic actions in the form of reactions. Write the reactions of pancreatic enzymes.
Answer:Glycogen + starch \( \xrightarrow{\text{Pancreatic amylase}} \) Disaccharides Fat molecules \( \xrightarrow{\text{Lipase}} \) Fatty acids + monoglycerides Typsinogen \( \xrightarrow{\text{Enterokinase}} \) Trypsin Proteins, proteoses, peptones \( \xrightarrow{\text{Trypsin}} \) polypeptides Chymotrypsinogen \( \xrightarrow{\text{Trypsin}} \) chymotrypsin Polypeptides \( \xrightarrow{\text{Chymotrypsin}} \) Dipeptides Nucleic acids \( \xrightarrow{\text{Nucleases}} \) Nucleotides Nucleotides \( \xrightarrow{\text{Nucleotidases}} \) Nucleosides + phosphate Nucleosides \( \xrightarrow{\text{Nucleosidases}} \) Sugar + base
In simple words: Pancreatic enzymes break down major food components: pancreatic amylase digests carbohydrates, lipase breaks down fats, trypsin and chymotrypsin digest proteins, nucleases break down nucleic acids, and nucleotidases/nucleosidases further break down nucleotides.

🎯 Exam Tip: Clearly list each enzyme and its specific substrate and product in the reaction, focusing on the step-by-step breakdown of complex molecules.

Do It Yourself (Textbook Page No. 168)

Question 1.Observe the following reactions and explain in words. i. Maltose \( \xrightarrow{\text{Maltase}} \) Glucose ii. Sucrose \( \xrightarrow{\text{Sucrase}} \) glucose + fructose iii. Lactose \( \xrightarrow{\text{Lactase}} \) glucose + galactose iv. Dipeptides \( \xrightarrow{\text{Dipeptidase}} \) Amino acids v. Emulsified fats \( \xrightarrow{\text{Lipase}} \) fatty acids + monoglycerides
Answer:1. Maltase acts on maltose to form glucose. 2. Sucrase acts on sucrose to form glucose and fructose. 3. Lactase acts on lactose to form glucose and galactose. 4. Dipeptidase acts on dipeptides to form amino acids. 5. Emulsified fats are converted into fatty acids and glycerol by lipase.
In simple words: These reactions illustrate the final stages of digestion where specific enzymes break down disaccharides (maltose, sucrose, lactose) into monosaccharides, dipeptides into amino acids, and emulsified fats into fatty acids and monoglycerides.

🎯 Exam Tip: When explaining enzymatic reactions, always specify the substrate, the enzyme involved, and the final products clearly.

Use Your Brain Power (Textbook Page No. 168)

Question 1.Make a flow chart for digestion of carbohydrate.
Answer:Starch \( \downarrow \) Salivary amylase Disaccharides

🎯 Exam Tip: For flowcharts, ensure clear arrows and labels for each step, indicating the substance, the enzyme, and the product.

Question 2.What is a proenzyme? Enlist various proenzymes involved in process of digestion and state their function.
Answer:Proenzymes are synthesized in cells as an inactive precursor that undergo some modification before becoming catalytically active. The various proenzymes involved in process of digestion are as follows: - Pepsinogen: Pepsinogen when converted into its active form pepsin acts on proteins to form peptones and proteoses. - Trypsinogen: Trypsinogen when converted to it active form trypsin converts proteins, proteoses and peptones to polypeptides. - Chymotrypsinogen: Chymotrypsinogen when converted to active form chymotrypsin it converts polypeptides to dipeptides.
In simple words: Proenzymes are inactive enzyme precursors that must be activated to perform their digestive functions, like pepsinogen converting to pepsin for protein breakdown or trypsinogen to trypsin and chymotrypsinogen to chymotrypsin for further protein digestion.

🎯 Exam Tip: Define proenzyme first, then clearly list each proenzyme, its active form, and its specific role in breaking down food components for full marks.

Question 3.Differentiate between Chyme and Chyle.
Answer:

🎯 Exam Tip: When differentiating, use a comparative table and highlight key differences such as composition (acidic vs. alkaline, partially digested food vs. absorbed nutrients) and location in the digestive tract.

Question 4.Digestion of fats take place only after the food reaches small intestine. Give reason.
Answer:Digestion of fats takes place in small intestine because the presence of fats in small intestine stimulates the release of pancreatic lipase from pancreas and bile from liver. Pancreatic lipases hydrolyze fat molecules into fatty acids and monoglycerides and bile brings about emulsification of fats. Therefore, digestion of fats occur when food reaches small intestine.
In simple words: Fat digestion primarily occurs in the small intestine because it's where bile, essential for emulsification, and pancreatic lipase, the main fat-digesting enzyme, are released and become active.

🎯 Exam Tip: The critical components to mention are the roles of bile (emulsification) and pancreatic lipase (hydrolysis) in the small intestine for fat digestion.

Observe And Discuss (Textbook Page No. 169)

Question 1.Action of digestive juice in your group.
Answer:

🎯 Exam Tip: For this type of question, create a clear table with each digestive juice and its primary enzymatic or emulsifying actions for an organized and comprehensive answer.

Can You Recall? (Textbook Page No. 170)

Question 1.What is balanced diet?
Answer:Balanced diet is a diet which contains proper amount of carbohydrates, fats, vitamins, proteins and minerals to maintain a good health.
In simple words: A balanced diet provides all necessary nutrients-carbohydrates, fats, vitamins, proteins, and minerals-in appropriate amounts to sustain good health.

🎯 Exam Tip: Remember to list all major nutrient categories and emphasize the "proper amount" for maintaining health in your definition of a balanced diet.

Question 2.Explain the terms undernourished, over-nourished and malnourished in details.
Answer:- Undernourished: When supply of nutrients is less than the minimum amount of nutrients or food required for good health is called undernourished. - Over-nourished: The intake of nutrients is excessive. In over-nourished the amount of nutrients exceeds the amount required for normal growth. - Malnourished: Malnourished is a condition where a person's diet does not contain right amount of nutrients.
In simple words: Undernourishment means not getting enough nutrients, overnourishment means consuming excessive nutrients, and malnourishment is a broader term indicating an imbalance in nutrient intake, whether too little, too much, or the wrong kind.

🎯 Exam Tip: Clearly define each term by focusing on the quantity and balance of nutrient intake – less than required (undernourished), more than required (over-nourished), or an improper balance (malnourished).

Do You Know? (Textbook Page No. 170)

Question 1.What is gross calorific value?
Answer:The amount of heat liberated by complete combustion of 1g food in a bomb calorimeter is termed as gross calorific (gross energy) value.
In simple words: Gross calorific value is the total energy released when one gram of food is completely burned in a bomb calorimeter.

🎯 Exam Tip: Key terms to include are "complete combustion," "1g food," "bomb calorimeter," and "heat liberated" when defining gross calorific value.

Question 2.What is physiological value?
Answer:The actual energy produced by 1 g food is its physiological value.
In simple words: Physiological value is the actual amount of energy that the body can derive from 1 gram of food after digestion and absorption.

🎯 Exam Tip: Distinguish physiological value from gross calorific value by highlighting that it's the *actual* usable energy for the body, not just the total combustion energy.

Question 3.Name the following Energy content of food in animals is expressed in terms of?
Answer:Heat Energy
In simple words: The energy content of food for animals is expressed as heat energy.

🎯 Exam Tip: For simple naming questions, provide the direct and correct term without additional explanation.

Question 4.Complete the following table representing Gross calorific value and physiological value of food component.

🎯 Exam Tip: Memorize the standard gross calorific and physiological values for major food components like fats, proteins, and carbohydrates, and present them clearly in a table.

Find Out (Textbook Page No. 171)

Question 1.Find out the status of nialnutrition among children in Maharashtra and efforts taken by the government to overcome the situation. Search for various NGOs working in this field.
Answer:93,783 children have been diagnosed with severe acute malnutrition and 5.7 lakh with moderate acute malnutrition in Maharashtra. Steps taken by government to overcome malnutrition: 1. Promotion of infant and young child feeding practices. 2. Management of malnutrition at community and facility level by trained service providers. 3. Treatment of children with severe acute malnutrition at special units called the Nutrition Rehabilitation Centres (NRCs), set up at public health facilities. 4. A special program to combat micronutrient deficiencies of Vitamin A, Iron and Folic acid. 5. The initiatives like Mother and Child protection card, village health and nutrition days, are taken by the government for addressing the nutrition concerns in children, pregnant women and lactating mothers. Various NCOs working in this field: 1. Akshay Patra 2. Fight Hunger Foundation, 3. Feeding India, 4. No Hungry child
In simple words: Maharashtra faces significant child malnutrition, which the government addresses through initiatives like promoting proper feeding practices, establishing Nutrition Rehabilitation Centres, combating micronutrient deficiencies, and community-level interventions, supported by various NGOs dedicated to hunger and nutrition.

🎯 Exam Tip: For social impact questions, provide statistics (if available), list specific government programs or policies, and name relevant non-governmental organizations to demonstrate comprehensive understanding.

Question 2.Are jaundice and hepatitis same disorders?
Answer:Jaundice and Hepatitis are two different disorders. Jaundice: Jaundice occurs when the rate of bilirubin production exceeds the rate of its elimination. It causes yellowing of skin and eyes. Hepatitis: It is a disease where there is inflammation of liver. It may be caused because of infection, over alcohol consumption, immune system disorder etc.
In simple words: Jaundice is a symptom characterized by yellow skin/eyes due to excess bilirubin, whereas hepatitis is an inflammation of the liver, often caused by infection or alcohol, and can be an underlying cause of jaundice.

🎯 Exam Tip: Clearly define each condition separately, highlighting that jaundice is a symptom (yellowing due to bilirubin) and hepatitis is a disease (liver inflammation with various causes).

Do You Know (Textbook Page No. 171)

Question 1.Alcoholism causes different disorders of liver like steatosis (fatty liver), alcoholic hepatitis, fibrosis and cirrhosis. Collect more information on these disorders and try to increase awareness against alcoholism in society. Collect information about NGOs working against alcoholism.
Answer:Steatosis (fatty liver): Steatosis is accumulation of fat in the liver. Treatment can help but it cannot be cured. Major risk factors are obesity and Diabetes type II, it is also associated with excessive alcohol consumption. Fatigue, weight loss and abdominal pain are some symptoms. It is a benign condition but in very smaller number of patients it can lead to liver failure. Treatment involves diet and exercise to reduce obesity. Alcoholic hepatitis: Alcoholic Hepatitis is liver inflammation caused by excessive consumption of alcohol. It occurs in people who drink heavily for many years. Symptoms like yellowing of skin and eye, accumulation of fluid in stomach which leads to increase in stomach size. Treatments like completely stopping of alcohol consumption, hydration and nutrition care are carried out. Administration of steroid drugs reduces liver inflammation. Fibrosis: There is significant scarring of liver tissue in this condition. Fibrosis itself does not cause any symptoms. Diagnosis includes doctor's evaluation, blood tests and imaging tests, liver biopsy. Treatments include stopping the consumption of alcohol. There are no such effective drugs for curing of fibrosis. Cirrhosis: It is a chronic liver damage caused due to various reasons which leads to irreversible scarring of liver and liver failure. Causes of cirrhosis are chronic alcohol abuse and hepatitis. Patients may experience fatigue, weakness and weight loss. In later stages, patients may develop jaundice, abdominal swelling and gastrointestinal bleeding. In advanced stage, a liver transplant is required. NGOs working against alcoholism: 1. Muktangan Rehabilitation Centre 2. Anmol Jeevan Foundation 3. Sankalp Rehabilitation Trust 4. Kripa Foundation 5. Harmony Foundation 6. Hands for you Rehab Centre
In simple words: Alcoholism can lead to several liver disorders, including fatty liver (steatosis), inflammation (alcoholic hepatitis), scarring (fibrosis), and severe, irreversible damage (cirrhosis), with treatments focusing on alcohol cessation and supportive care, often requiring the help of rehabilitation centers and NGOs.

🎯 Exam Tip: When detailing liver disorders, define each condition, state its symptoms and causes, and outline common treatments. Also, list relevant NGOs to fulfill the awareness aspect of the question.