CBSE Class 11

CBSE Class 11

NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases

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NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases

These Solutions are part of NCERT Solutions for Class 11 Biology. Here we have given NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases.

Question 1.
Define vital capacity. What is its significance?
Solution:
The maximum volume of air a person can breathe in after a forced expiration it is about 4000mL in a normal adult person. Vital capacity is higher in athletes and singers. Cigarette smokers have a lower vital capacity of the lungs. This includes ERC, TV, and IRV, or the maximum volume of air a person can breathe out after a forced inspiration.

Question 2.
State the volume of air remaining in the lungs after a normal breathing.
Solution:
The volume of air remaining in the lungs after normal respiration is called functional residual capacity. It includes ERV + RV = Expiratory reserve volume + residual volume

Question 3.
volume Diffusion of gases occurs in the alveolar region only and not in the other parts of the respiratory system. Why?
Solution:
Alveoli are the primary sites of the exchange of gases. The alveolar region is having enough pressure gradient to facilitate the diffusion of gases. Other regions of the respiratory system don’t have the required pressure gradient. Additionally, the membrane of alveoli is thin enough to facilitate the exchange of gases in a convenient manner.
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 1

Question 4.
What are the major transport mechanisms for CO2? Explain.
Solution:
Transport of carbon dioxide: About 4 ml of carbon dioxide is transported by every 100 ml of blood.
C02 is transported in three forms in the blood.
(i) In the dissolved form in plasma about 7% of C02 dissolves in the plasma of blood, just as it gets dissolved in water.
(ii) As bicarbonates
Erythrocytes have a high concentration of the enzyme, carbonic anhydrase which catalyzes the following reactions;
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 2
About 70% of C02 is transported as bicarbonates.

(iii) As carbaminohaemoglobin
C02 combines with the globin part of haemoglobin and forms carbamino haemoglobin. About 23% of CO2 transported in this manner.

Question 5.
What will be the pO2 and pCO2 in the atmospheric air compared to those in the alveolar air?
(i) pO2 lesser, pCO2higher
(ii) pO2 higher, pCO2lesser
(iii) pO2 higher, pCO2 higher
(iv) pO2 lesser, pCO2lesser
Solution:
(ii) pO2 higher, pCO2 lesser
pO2 higher will create the pressure gradient to facilitate the movement of O2 from atmosphere to alveoli and pCO2 lesser will create the movement of CO2 from alveoli to atmosphere.

Question 6.
Explain the process of inspiration under normal conditions.
Solution:
The intake of air into the lungs is known as inspiration. Inspiration occurs when the pressure within the lungs is less than the atmospheric pressure. It is initiated by the contraction of the diaphragm which increases the volume of the thoracic chamber in the anteroposterior axis. The contraction of external intercostal muscles lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorsoventral axis. The overall increase in the thoracic volume causes a similar increase in pulmonary volume which decreases the intra-pulmonary pressure to less than the atmospheric pressure which forces the air from outside to move into the lungs.

Question 7.
How is respiration regulated?
Solution:

  1. Respiratory rhythm centre, present in medulla region of brain is responsible for respiration regulation.
  2. Its function can be moderate by pneumotaxic centre, present in pons region of brain.
  3. A chemosensitive area present adjacent to rhythm centre, is highly sensitive to C02 and H+.
  4. Chemosenstive centre due to increase in C02 and H+ can signal the rhythm centre to make adjustment to eliminate these substances.
  5. Receptors associated with aortic arch and carotid artery also can recognise changes in CO2 and H+ concentration and send necessary signals to rhythm centre for remedial actions.

Question 8.
What is the effect of pC02 on oxygen transport?
Solution:
At low pC02, blood can carry the maximum amount of oxygen as oxyhemoglobin. At high pCO2, the affinity for oxygen decreases and oxyhaemoglobin dissociates to free oxygen.
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 3
So at high pC02, oxygen transport is inhibited.

Question 9.
What happens to the respiratory process in a man going up a hill?
Solution:
There is a fall of PO2 level at high altitudes. This lowers alveolar PO2 and consequently reduces the diffusion of oxygen from the alveolar air to the blood. So oxygenation of the blood is decreased progressively.

After some time, the affected person gets adjusted to the surroundings due to which the heart rate is accelerated, RBC count in the blood is increased, haemoglobin level and oxygen-carrying capacity are also increased.

Question 10.
What is the site of gaseous exchange in an insect?
Solution:
Insects have a complex system of intercommunicating air tubes called tracheae to enable them to exchange gases between the environment and the body cells (tracheal respiration).

Question 11.
Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?
Solution:
The curve in which the percentage saturation of hemoglobin with O2 is plotted against the partial pressure of oxygen (PO2) is called the oxygen dissociation curve. At a PO2 of 100 mm Hg, 100 percent saturation of Hb takes place 90% saturation of Hb takes place even at a P02 of 60mm Hg. An I fall of PCX, from 100 to 60mm Hg will cause only 10% decrease in saturation of Hb. Hence the curve takes the shape of a sigmoid.

Question 12.
Have you heard about hypoxia? Try to gather information about it, and discuss it with your friends.
Solution:
Hypoxia is the condition in which there is a deficiency of oxygen at the tissue level.

  • Arterial hypoxia: It’s because of low level of oxygen in the blood. It occurs when the atmosphere does not contain enough oxygen and there is obstruction in the respiratory passage.
  • Anaemic hypoxia: It is due to very low level of haemoglobin in the blood.
  • Stagnant hypoxia: It is due to the inadequate blood flow to deliver oxygen to the tissue.
  • Histoxic hypoxia: It is due to the presence of toxic substances in the oxygen inhaled,  e.g.: Cyanide poisoning.

Question 13.
Distinguish between
(a) IRV and ERV
(b) Inspiratory capacity and Expiratory capacity.
(c) Vital capacity and Total lung capacity.
Solution:
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 4

Question 14.
What is tidal volume? Find out the tidal volume (approximate value) for a healthy human in an hour.
Solution:
The volume of air inspired or expired/breath during normal respiration is approx. 500 ml., i.e., a healthy man can inspire or expire approximately 6000 to 8000 ml of air per minute.

VERY SHORT ANSWER QUESTIONS

Question 1.
Name the enzyme which catalyses the bicarbonate formation in RBCs.
Solution:
Enzyme carbonic anhydrase.

Question 2.
What is carbamino haemoglobin?
Solution:
It is a complex formed by the combination of carbon dioxide with the globin part of haemoglobin.

Question 3.
What is tidal volume?
Solution:
The volume of air inspired or expired with every normal breath during effortless respiration is called tidal volume.

Question 4.
What term is used for the volume of air left in the lungs even after the most powerful expiration?
Solution:
Residual volume.

Question 5.
Name the respiratory organ of
(a) Butterfly
(b) Frog larva.
Solution:
(i) Butterfly – trachea
(ii) Frog larva – gills.

Question 6.
What is the role of oxyhaemoglobin after releasing molecular oxygen in the tissue?
Solution:
Oxyhaemoglobin after releasing oxygen collects carbon dioxide from the tissue and form carbaminohaemoglobin.

Question 7.
What are the two factors that contribute to the dissociation of oxyhaemoglobin in the atrial blood to release’ molecular oxygen in active tissue?
Solution:
The two factors are :
(a) Lowp02
(b) HighpC02

Question 8.
Name the double-walled sac which covers the lungs in mammals.
Solution:
Pleura.

Question 9.
What prevents the collapsing of our trachea during breathing ?
Solution:
C-shaped cartilages at regular intervals.

Question 10.
Define inspiratory reserve volume.
Solution:
The extra volume of air that can be inspired beyond the normal tidal volume, is called inspiratory reserve volume.

Question 11.
Which part(s) of the brain control(s) breathing movements?
Solution:
Medulla and pons.

Question 12.
What is oxyhaemoglobin?
Solution:
Oxyhaemoglobin is a complex formed when oxygen combies with the Fe2+ part of haemoglobin.

Question 13.
How much of oxygen is transported by 100 ml of blood under normal physiological conditions?
Solution:
About 5 mL.

Question 14.
Write the chemical reaction catalysed by enzyme carbonic anhydrase.
Solution:
Carbonic anhydrase catalyses the following reaction:
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 5

Question 15.
How does penumotaxic centre alter the respiratory rate?
Solution:
Pneumotaxic centre can reduce the duration of inspiration and alter the respiratory rate.

Question 16.
What is the percentage of C02 transported as sodium bicarbonate?
Solution:
70% of C02 is transported as sodium bicarbonate.

Question 17.
What will happen if the human blood becomes acidic?
Solution:
Oxygen carrying capacity of haemoglobin will decrease.

SHORT ANSWER QUESTIONS

Question 1.
Write four conditions necessary to facilitates efficient gaseous exchange between human respiratory surface and the environment.
Solution:
Conditions for efficient gas exchange are as follows:
(a) The membrane should be thin.
(b) It should be highly vascularized.
(c) It should be highly permeable to gases.
(d) There should a partial pressure difference on both sides of lung.

Question 2.
Differentiate between pharynx and larynx.
Solution:
The main differences between the pharynx and larynx are as follows:
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 6

Question 3.
Why is hemoglobin called a conjugated protein? What happens to the molecule at a high and low partial pressure of oxygen?
Solution:
Hemoglobin: It is called conjugated protein because it consists of a basic protein globin and a non-protein heme.
The haemoglobin when exposed to the high partial pressure of oxygen combines with oxygen to form oxyhaemoglobin which carries 4 molecules of oxygen loosely bound to the four Fe2+ ions. When this oxyhaemoglobin reaches the tissues where there is low oxygen pressure oxyhaemoglobin dissociates into oxygen and deoxyhemoglobin.

Question 4.
Differentiate between inspiratory capacity and expiratory capacity.
Solution:
The differences between inspiratory and expiratory capacity are :
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 7

Question 5.
Diffusion of gases occurs in the alveolar region only and not in the other parts of the respiratory system. Why?
Solution:
The alveoli have very thin walls consisting of squamous epithelium. The alveolar wall is provided with an extensive network of blood capillaries; due to the intimate contact of the blood capillaries and alveolar wall, there is an exchange of gases taking place easily. In the other part the membrane/wall is not so thin to allow for diffusion.

Question 6.
What percentage of oxygen is transported by erythrocytes in the blood? What happens to the remaining?
Solution:
About 97% of the oxygen is transported by erythrocytes. The remaining 3% is transported in dissolved form in the plasma.

Question 7.
What is asthma? Explain.
Solution:
Asthma: It is the hypersensitivity of bronchioles to any foreign substance, characterized by the spasm of the smooth muscles of the walls of the bronchioles.

Question 8.
What is emphysema? What is its major cause?
Solution:
Emphysema: Emphysema is a chronic disorder is which alveolar walls are damaged and hence the surface area for exchange of. gases is reduced. It is caused mainly by cigarette smoking.

Question 9.
Draw a labelled diagram of a section of an alveolus with a pulmonary capillary.
Solution:
NCERT Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases 8

Question 10.
What will happen if the patient has been inhaling polluted air containing high content of CO?
Solution:
Hemoglobin has much more affinity about 250 times for CO than oxygen. It readily combines with CO to form the most stable compound called carboxyhemoglobin. It may be fatal for the patient.

Question 11.
What is pneumonia? What are its causes?
Solution:
Pneumonia is a respiratory disease in which oxygen has difficulty in diffusing through the flammed alveoli and the blood O2 may be drastically reduced and blood PCO2 remains normal. It is caused by streptococcus pneumonia. Its symptoms are trembling, pain in the chest, fever, cough, etc. It is mostly observed in children and old age.

LONG ANSWER QUESTIONS

Question 1.
What do you mean by occupational lung disease? Enumerate the prevention measure that should be adopted by a person likely to be exposed to substances that cause occupational diseases?
Solution:
Occupational lung disease as the name suggests it is the disease of lung due to the occupation of the human.
Cause: These are caused by harmful substances, such as gas fumes or dust, present in the environment where a person works. Silicosis and asbestoses are common examples, which occur due to chronic exposure of silica and asbestos dust in the mining industry.
Symptoms: It is characterized by the proliferation of fibrous connective tissue (fibrosis) of upper part of lung, causing inflammation.
Prevention: The occupational disease expresses symptoms after chronic exposure (i.e., 10-15 years or even more). Most of the occupational diseases including silicosis and asbestosis is are incurable. Therefore, the person which is exposed to such irritants should adopt preventive measures. These protective measures are as follows:
(i) Minimize the exposure of harmful dust at the workplace.
(ii) Workers should be informed about the harm of exposure to such dust.
(iii) Workers must have protective gear and clothing at the workplace.
(iv) health of the workers should be regularly checked up.

Question 2.
Explain the regulation of respiration by the nervous system.
Solution:
Regulation of respiratory rhythm

  • The ability to maintain and moderate the respiratory rhythm according to the demand of the body tissues is due to neural control.
  • The respiratory rhythm centre located in the medulla of the brain, is primarily responsible for this regulation, f Pneumotaxic centre present in the brain functions as the ‘switch off point for regulation; by altering the duration of inspiration, it can alter the respiratory rate.
  • A chemosensitive area is situated adjacent to the rhythm centre; it is highly sensitive to carbon dioxide and hydrogen ions.
  • An increase in the concentration of these substances activates this centre which in turn sends signals to the rhythm centre to make necessary adjustments in the respiratory process.
  • Receptors associated with aortic arch and carotid artery also are sensitive to carbon di oxide and H+ ions; they too send signals to the respiratory rhythm centre.
  • Oxygen plays only an insignificant role in the regulation of respiratory rhythm.

Question 3.
How does the exchange of respiratory gases take place in the alveoli or lungs?
Solution:
Gaseous exchange in alveoli:

  • The alveolar wall is very thin and contains a rich network of interconnected capillaries.
  • Due to this, the alveolar wall seems to be a sheet of flowing blood and is called the respiratory membrane.
  • It consists mainly of the alveolar epithelium, epithelial basement membrane, a thin interstitial space, capillary basement membrane, and capillary endothermal membrane. All these layers cumulatively form a membrane of 0.2 mm thickness.
  • The respiratory membrane has a limit of gas exchange between alveoli and pulmonary blood. It is called diffusing capacity. It is dependent on the solubility of respiratory gases.
  • The partial pressure of oxygen (p02) in the alveoli is higher (104 mm Hg) than that in the deoxygenated blood in the capillaries of the pulmonary arteries (40 mm Hg). As the gases diffuse from higher to a lower concentration, the movement of oxygen is from the alveoli to the blood. The reverse is the case in relation to carbon dioxide.
  • The partial pressure of carbon dioxide (pC02) is higher in deoxygenated blood (45 mm Hg), than in alveoli (40 mm Hg), therefore, CO2 passes from the blood to the alveoli.

Question 4.
How are inspiration and expiration take place in humans?
Solution:
The inflow (inspiration) and outflow (expiration) of air occur between the atmosphere and lungs by the expansion and contraction of lungs.
Inspiration: It is the process by which fresh air enters the lungs.

  • The external intercostal muscles present between the ribs contract and pull these ribs and sternum upward and outward increasing the volume to the thoracic cavity.
  • The diaphragm becomes flats and gets lowered by the contraction of its muscles thereby increasing the volume of the thoracic cavity.
  • The abdominal muscles relax and allow the compression of the abdominal organ by the diaphragm.
  • As the volume of the thoracic cavity increases and as a result, there is a decrease in air pressure in the lungs. The greater pressure outside the body causes air to flow rapidly into the nostrils through the respiratory tract to the lungs.

Expiration: It is a process by which foul air (CO2) is expelled out from the lungs.

  • Internal intercostal muscles contract so that they pull in ribs downward and inward decreasing the size of the thoracic cavity.
  • The muscle fibres of the diaphragm relax making it convex, decreasing the volume of the thoracic cavity.
  • Contraction of abdominal muscles compresses this abdomen and pushes it towards the diaphragm.
    The overall volume of the thoracic cavity decrease and foul air goes outside from the cavities of alveoli through the respiratory tract.

We hope the NCERT Solutions for Class 11 Biology at Work Chapter 17 Breathing and Exchange of Gases, help you. If you have any query regarding NCERT Solutions for Class 11 Biology at Work Chapter 17 Breathing and Exchange of Gases, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination

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NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination

These Solutions are part of NCERT Solutions for Class 11 Biology. Here we have given NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination.

Question 1.
Define Glomerular Filtration Rate (GFR).
Solution:
The amount of filtrate formed by the kidneys per minute is called glomerular filtration rater (GFR). GFR in a healthy individual is approximately 125ml/minute i.e. 180 lines per day.

Question 2.
Explain the autoregulatory mechanism of GFR.
Solution:
This mechanism in Kidney is present to regulate the glomerular filtrate rate.

  • Juxtaglomerular apparatus (JGA) is a specialized cellular region located where the distal convoluted tubule and afferent arteriole, come in contact with each other.
  • A fall in GFR can activate the JG cells to release renin which acts through a complex series of reactions called renin-angiotensin aldosterone mechanism, which can stimulate blood flow and thereby the GFR back to normal.

Question 3.
Indicate whether the following statements are true or false :
(i) Micturition is carried out by a reflex.
(ii) ADH helps in water elimination, making the urine hypotonic.
(iii) Protein-free fluid is filtered from blood plasma into the Bowman’s capsule.
(iv) Henle’s loop plays an important role in concentrating the urine.
(v) Glucose is actively reabsorbed in the proximal convoluted tubule.
Solution:
(i) True
(ii) False
(iii) True
(iv) True
(v) True.

Question 4.
Give a brief account of the countercurrent mechanism.
Solution:
The loop of Henle and vcisa recta are responsible for concentrating the filtrate. The mechanism is called a counter-current mechanism. The flow of filtrate in limbs of Henle’s loop and vasa recta is in opposite direction so, forms a counter-current system. The proximity, as well as counter-current in them, maintains osmolarity increasing 300 mOsmolL-1 in the cortex and 1200 mOsmolL- 1 in inner medulla.

Question 5.
Describe the role of the liver, lungs and skin in excretion.
Solution:
Liver: This largest gland in our body, secretes bile-containing substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins and drugs. Most of these substances ultimately pass out along with digestive wastes.

Lungs: Lungs remove large amounts of CO2, about 18 liters/day, and also significant qualities of water every day.

Skin: The sweat and sebaceous glands in the skin eliminate certain substances through their secretions. Sweat is a watery fluid containing NaCI, small amounts of urea, lactic acid etc. Sebaceous glands eliminate certain substances like sterols, hydrocarbons, and waxes through sebum.

Question 6.
Explain micturition.
Solution:
Urine formed by the nephrons is ultimately carried to the urinary bladder where it is stored till a voluntary signal is given by the central nervous system (CNS). This signal is initiated by the stretching of the urinary bladder as it gets filled with urine. In response, the stretch receptors on the walls of the bladder send signals to the CNS. The CNS passes on motor messages to initiate the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine. The process of release of urine is called micturition and the neural mechanisms causing it is called the micturition reflex.

An adult human excretes on average, 1.5 liters of urine per day. The urine formed is a light yellow colored watery fluid that is slightly acidic (pH-6.0) and has a characteristic odor. On average, 25-30 gm of urea is excreted out per day. Various conditions can affect the characteristics of urine. Analysis of urine helps in the clinical diagnosis of many metabolic disorders as well as malfunctioning of the kidneys. For example, the presence of glucose (Glycosuria) and ketone bodies (ketonuria) in urine are indicative of diabetes mellitus.

Question 7.
Match the items of Column I with those of column II.
Column I                                              Column II
(a) Ammonotelism                            (i) Birds
(b) Bowman’s capsule                       (ii) Water reabsorption
(c) Micturition                                    (iii) Bony fish
(d) Uricotelism                                   (iv) Urinary bladder
(e) ADH                                               (v) Renal tubule
Solution:
(a) – (iii) Bony fish
(b) – (v) Renal tubule
(c) – (iv) Urinary bladder
(d) – (i) Birds
(e) – (ii) Water reabsorption

Question 8.
What is meant by the term osmoregulation?
Solution:
Osmoregulation is the mechanism of maintaining water, blood, body fluid, and ionic (salt) balance in the body.

Question 9.
Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why?
Solution:
Land animals have an integument that is impervious to gas exchange. Ammonia is highly toxic and it has to be eliminated as rapidly as it is formed. It requires a large volume of water for its elimination. They do not have access to such a large volume of water needed for the elimination of ammonia. So, they are either ureotelic or uricotelic.

Question 10.
What is the significance of the juxtaglomerular apparatus (JGA) in kidney function?
Solution:
The JGA plays an important role in the regulation of kidney function. A fall in glomerular blood flow / glomerular blood pressure / GFR can activate the JG cells to release renin which converts angiotensinogen in the blood to angiotensin I and further to angiotensin II. Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR. It also activates the adrenal cortex to release Aldosterone. Aldosterone causes reabsorption of Na+ and water from the distal parts of the tubule. This also leads to an increase in blood pressure and GFR. This mechanism is known as the Renin-Angiotensin mechanism.

Question 11.
Name the following:

  1. A chordate animal having flame cells as excretory structures.
  2. Cortical portions projecting between the medullary pyramids in the human kidney.
  3. A loop of capillary running parallel to Henle’s loop.

Solution:

  1. Amphioxus.
  2. Columns of Bertini.
  3. Vasa recta.

Question 12.
Fill in the gaps:

  1. Ascending limb of Henle’s loop is……………… to water whereas the descending limb is………….to it.
  2. Reabsorption of water from distal parts of the tubules is facilitated by hormone………………
  3. Dialysis fluid contains all the constituents as in plasma except…………….
  4. A healthy adult human excretes (on an average)………….. gm of urea/day.

Solution:

  1. impermeable, permeable
  2. ADH (vasopressin)
  3. nitrogenous wastes
  4. 25 to 30 gm

VERY SHORT ANSWER QUESTIONS

Question 1.
Name the nitrogenous waste excreted by larval and adult stage of frog respectively.
Solution:
Larval stage – ammonia, Adult stage – urea.

Question 2.
In which organ ammonia is converted to urea?
Solution:
Liver.

Question 3.
Define ammonotelism.
Solution:
The excretion of ammonia is called ammonotelism.

Question 4.
What is hemodialysis?
Solution:
The process of removal of excess urea from the blood of a patient (normally suffering from uremia) using an artificial kidney is known as hemodialysis

Question 5.
Define ketonuria.
Solution:
The presence of high ketone bodies in the urine is called ketonuria.

Question 6.
What are the columns of Bertini?
Solution:
These are the extension of the renal cortex between the medullary pyramids as renal columns.

Question 7.
In which part of the nephron does filtration take place?
Solution:
Bowman’s Capsule/Renal Corpuscle

Question 8.
What difference is observed in the ascending and descending limbs of Henle’s loop with g reference to permeability to water?
Solution:
Ascending limb is impermeable to water and permeable to solutes.
Descending limb is permeable to water and impermeable to solutes.

Question 9.
Name the body part through which ammonia is eliminated in a bony fish.
Solution:
Gill membranes.

Question 10.
What is vasa recta ?
Solution:
The U-shaped peritubular capillary that runs parallel to the Henle’s loop is called vasa recta.

Question 11.
What is the driving force for glomerular filtration?
Solution:
The driving force for filtration is the blood pressure in the glomerular capillaries.

Question 12.
How are the filtration slits formed?
Solution:
The podocytes are arranged in an intricate manner so as to leave some minute spaces called filtration slits.

Question 13.
Why is glomerular filtration also called as ultrafiltration?
Solution:
Blood is filtered so finely through these membranes, that almost all the constituents of the plasma except the proteins pass onto the lumen of the bowman’s capsule. Therefore, it is considered as a process of ultrafiltration.

Question 14.
Name the mechanism that acts as a check for the Renin-angiotensin mechanism.
Solution:
Arterial Natriuretic Factor (ANF) Mechanism.

Question 15.
What is uremia?
Solution:
Uremia is a condition of excess accumulation of urea in the blood caused by the malfunctioning ofkidneys.

Question 16.
What term is given to the inflammation of glomerulus in nephron?
Solution:
Glomerulonephritis.

Question 17.
Which limb of loop of Henle is impermeable to water?
Solution:
Bowman’s capsule and glomerulus are collectively called malpighian body.

Question 18.
What is afferent arteriole?
Solution:
Blood vessels leading to glomerulus is called afferent arteriole.

Question 19.
Which hormone promotes the reabsorption of water from glomerular filtrate?
Solution:
Vasopressin promotes reabsorption of water from the glomerular filtrate.

SHORT ANSWER QUESTIONS

Question 1.
How does the proximal convoluted tubule of the nephron contribute to homeostasis?
Solution:
All essential nutrients and 70-80 percent of electrolytes and water are reabsorbed by the PCT segment. So it helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO3-” from it.

Question 2.
What are the functions of nephridia? Name an animal having protonephridia
Solution:
Nephridia help to eliminate nitrogenous wastes and maintain a fluid and ionic balance. Protonephridia are present in Amphioxus, Rotifers, Planaria, etc.

Question 3.
Kidney do not play a major role in excretion in ammonotelic animals. Justify.
Solution:
Ammonia is readily soluble in water and diffuses across the body surface.
In fish, it is excreted as ammonium ions through gill surface. So kidneys do not have any significant role in the elimination of ammonia.

Question 4.
What are the functions of ADH?
Solution:
(i) ADH facilites water absorption from the distal tubule.
(ii) It also affect kidney function by its constrictor effects also on blood vessels.

Question 5.
What is the ultimate method of correcting acute renal failure? Describe.
Solution:
Kidney transplantation is the ultimate method in the correction of acute renal failures (kidney failure). A functioning kidney is used in transplantation from a donor, preferably a close relative, to minimize its chances of rejection by the immune system of the host.

Question 6.
Mention the role of DCT in urine formation.
Solution:
Distal convoluted tubule plays the following roles:

  • Conditional reabsorption of Na+ & water takes place in this segment.
  • It also reabsorbs HCO3-”
  • It helps in the selective secretion of hydrogen and potassium ions to maintain the pH and sodium-potassium balance in the blood.

Question 7.
Why do persons suffering from very low blood pressure pass no urine?
Solution:
The blood passes into the glomerulus under high pressure during glomerular filtration. If blood pressure is less then it results in the failure of the ultrafiltration process in the glomerulus and hence, no urine formation occurs.

Question 8.
Name the passage in sequence through which urine passes from kidneys to the outside in humans. How is urine prevented from flowing back into the ureters?
Solution:
Kidneys → ureters → urinary bladder → urethra
Urine is prevented from flowing back into the ureters because the terminal part of each ureter passes obliquely through the bladder wall.

Question 9.
(a) The two human kidneys do not occur at the same level-explain.
(b) Why are Kidneys called retro-peritoneal?
Solution:
(a) Left kidney is slightly longer, narrower, median, and lies at a level 1.25 cm higher than the right kidney. The right kidney is lower in position due to the presence of the right lobe of the liver.
(b) Retroperitoneal. It is space that lies between the peritoneum and vertebral column, Kidneys occur in this space so that they are lined by peritoneum only on the ventral side.

Question 10.
Differentiate between Cortical Nephron and Juxtamedullary Nephron.
Solution:
NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination 1

Question 11.
What is the chemical composition of human urine?
Solution:
Human urine is transparent, yellowish in colour and variable in chemical composition. It
consists primarily of water (95 %), with organic solutes including urea (2.6%), creatinine, uric acid, and trace amounts of enzymes, carbohydrates, hormones, fatty acids, pigments, and mucins, and inorganic ions such as Na+, K+, Cl– Mg2+, Ca2+, and phosphates.

Question 12.
What is Erythropoietin? What is its function?
Solution:
Erythropoietin is a glycoprotein hormone that controls erythropoiesis, or the formation of red blood cells. It acts as a cytokine (proteinsignaling molecule) for RBC precursor in bone marrow. It is produced by enterstitial fibroblasts in the kidney in close association with peritubular capillary and tubular epithelial tubule.

Long ANSWER QUESTIONS

Question 1.
Describe the structure of the kidney.
Solution:

  • Kidneys are reddish-brown, bean-shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.
  • Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120-170 g.
  • Towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter.
  • Inner to the hilum is a broad funnel-shaped space called th& renal pelvis with projections called calyces.
  • The outer layer of kidney is a tough capsule. Inside the kidney, there are two zones, an outer cortex and an inner medulla.
  • The medulla is divided into a few conical masses (medullary pyramids) projecting into the calyces (sing.: calyx). The cortex extends in between the medullary pyramids as renal columns called Columns of Bertini.
    NCERT Solutions for Class 11 Biology Chapter 19 Excretory Products and their Elimination 2

Question 2.
Describe the role of organs other than the kidney in the process of excretion in human beings.
Solution:

  • The organs other than kidney involved in the process of excretion are (i) Lungs (ii) Skin (iii) Liver (iv) Intestine (v) Salivary glands.
  • Our lungs remove large amounts of C02 (18 liters/day) and also significant quantities of water every day. The liver, the
  • largest gland in our body, secretes bile-containing substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, and drugs. Most of these substances ultimately pass out alongwith digestive wastes.
  • The sweat and sebaceous glands in the skin can eliminate certain substances through their secretions.
  • The sweat produced by the sweat glands is a watery fluid containing NaCl, small amounts of urea, lactic acid, etc.
  • Though the primary function of sweat is to facilitate a cooling effect of the body surface, it also helps in the removal of some of the wastes mentioned above.
  • Sebaceous glands eliminate certain substances like sterols, hydrocarbons, and waxes through sebum. This secretion provides a protective oily covering for the skin.

Question 3.
Describe the structure of nephron.
Solution:
Structure of nephron
A nephron has two parts-the glomerulus and the renal tubule
(i) Glomerulus: It is a tuft of capillaries formed by the afferent arteriole, which is a fine branch of the renal artery.
(ii) Renal tubule has three-part
(a) proximal convoluted tubule
(b) loop of Henle
(c) distal convoluted tubule
(a) Proximal convoluted tubule –

  1. The renal tubule is closed at the proximal, end; it is expanded and curved inwardly. form a double-walled cup-shaped structure called Bowman’s capsule.
  2. The glomerulus is located in the hollow of the Bowman’s capsule and together they constitute the renal corpuscle.
  3. The lumen of the capsule is continuous with the narrow lumen of the entire tubule.
  4. The tubule continues to form a highly convoluted proximal convoluted tubule (PCT).

(b) Loop of Henle – It arises from the end of the proximal convoluted tubule and ends at the starting of the distal tubule.
It is hairpin-like, with a descending limb (that extends into the medulla) and an ascending limb, that crosses back to the cortex.
(c) Distal convoluted tubule –

  1. The ascending limb, on entering the cortex becomes the distal convoluted tubule.
  2. It then continues as a short straight collecting tubule, that joins the collecting duct.
  3. Each collecting duct receives the collecting tubule of a number of nephrons.
  4. Many collects converge, ran through renal pyramids, and open into the renal pelvis through the openings called renal papillae, at the tip of pyramids.

Question 4.
Describe the process of hemodialysis.
Solution:
Haemodialysis:

  • Blood from the artery of a uremia patient is taken, cooled to 0°C, and mixed with an anti-coagulant like heparin.
  • The unit contains a coiled cellophane tube surrounded by a fluid (dialyzing fluid) having the same composition as that of plasma except for the nitrogenous wastes.
  • The porous cellophane membrane of the tube allows the passage of molecules based on the concentration gradient.
  • As nitrogenous wastes are absent in the dialysing fluid, these substances freely move out, thereby clearing the blood.
  • The cleared blood is pumped back to the body through a vein after adding anti-heparin to it. This method is a boon for thousands of uremic patients all over the world.

We hope the NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 19 Excretory Products and their Elimination, help you. If you have any query regarding NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 19 Excretory Products and their Elimination, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 11 English Hornbill Chapter 2 We’re Not Afraid to Die

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Here we are providing NCERT Solutions for Class 11 English Hornbill Chapter 2 We’re Not Afraid to Die. Students can get Class 11 English We’re Not Afraid to Die NCERT Solutions, Questions and Answers designed by subject expert teachers.

We’re Not Afraid to Die… If We Can All Be Together NCERT Solutions for Class 11 English Hornbill Chapter 2

We’re Not Afraid to Die… If We Can All Be Together NCERT Text Book Questions and Answers

We’re Not Afraid to Die… If We Can All Be Together Understanding the text

Question 1.
List the steps taken by the captain
(i) to protect the ship when rough weather began.
(ii) to check the flooding of the water in the ship.
Answer:
(i) to protect the ship when rough weather began.
Answer:
The captain slowed the boat down, dropped the storm jib and lashed a heavy mooring rope in a loop across the stem. Then they double-lashed everything, went through their life raft drill, attached “lifelines, donned oilskins and life jackets and waited.”

(ii) to check the flooding of the water in the ship.
Answer:
As the water started accumulating in the ship, the captain did not dare to abandon the wheel to examine the waterlogging. When Mary informed him that the decks were smashed and the boat was full of water, he gave the wheel to Mary and made it to the hatch. Larry and Herb were pumping out the water frantically. He found a hammer, screws and canvas, and walked back to the deck with difficulty.

He made some repairs. He stretched the canvas and secured that the waterproof hatch covers across the gaping holes. Some water continued to stream below, but most of it was now being deflected over the side. But soon the hand pumps started to block up with the debris floating around the cabins and the electric pump short-circuited. He found the two spare hand pumps had been overboard. Then he took the electric pump and connected it to an out-pipe and managed to pump out the water.

Question 2.
Describe the mental condition of the voyagers on 4 and 5 January.
Answer:
After battling with the waves and continuously pumping out water for thirty-six hours, on 4 January, the voyagers managed to pump out almost all the water that had accumulated and had to keep pace with the water that was still coming in. Then they hoisted the storm jib and sailed towards where they thought the two islands were. It was then that they were relieved and ate their first meal in almost two days. But much to their disappointment, at 4 p.m. black clouds gathered behind them.

The wind was back to 40 knots and the sea was getting higher. The weather continued to get worse throughout the night, and by dawn on 5 January, the situation was again distressing. The author tried to comfort the children, who seemed to be resigned to their fate. He was resolute to fight the sea but by the evening, Mary and he sat together holding hands, as the water seeped in through the broken planks. Both of them felt that their end was very near.

Question 3.
Describe the shifts in the narration of the events as indicated in the three sections of the text. Give a subtitle to each section.
Answer:
The text has been divided into three sections. The narration shifts as the events unfold. The first section deals with the narrator’s desire to go sailing around the world, the preparations they made, the onset of the journey and the coming storm. In this section, the narrator sums up more than sixteen years of preparations and the first 3,500 kilometres of their journey in a few paragraphs.

The second section describes the storm and the damage caused to the boat by the storm. The narrator describes in detail the events of 2 January when their ship was buffeted by the storm. He mainly deals with the action taken to avert disaster. In the third section, the narrator steers the ship to safety at He Amsterdam.

In this section, he describes the events of two days and focuses on the emotions of the members of the family as the near-tragedy drew them closer together. The 1 st section can be subtitled .The sea voyage and its challenges, the 2nd – Damages caused by the storm, and the 3rd- Finding lie Amsterdam.

We’re Not Afraid to Die… If We Can All Be Together Talking about the text

Discuss the following questions with your partner.

Question 1.
What difference did you notice between the reaction of the adults and the children when faced with danger?
Answer:
When the adults were faced with danger, they were anxious and sought out ways of battling it. For instance, when they faced rough weather for the first time, they fastened everything, went through their life raff drill, attached lifelines, put on oilskins and life jackets. As the ship flooded with water, Mary panicked and the narrator put her at the wheel, struggled with tools till the ship was waterproof and the water had been bailed out.

They assessed the situation, tried to adopt the best possible strategy for coping with the situation but were often dejected. When the narrator was thrown overboard, he accepted death as inevitable. Similarly, when the motion of the ship brought more and more water in through the broken planks, Mary and the narrator sat holding hands as both felt the end was very near.

On the other hand, Sue hurt herself. Her head had swollen a lot, she had two huge black eyes, and a deep cut on her arm but this did not worry her. The situation worsened and when the author tried to comfort the children on 5 January, Jon said that they were not afraid of dying if the family could be together. due, who was injured, moved up to him and gave him a card she had made. It was a message to hope for the best. The probable reason for the difference in reaction is that the children did not realise the gravity of the situation, like the adults, or that they do not cling on to life like adults.

Question 2.
How does the story suggest that optimism helps to endure “the direst stress”?
Answer:
It was the sheer optimism of the narrator and the two men in the crew, Larry and Herb, that helped them carry on in the face of life-threatening dangers. They celebrated Christmas despite the gales. When the storm struck and the narrator was flung overboard, he did not give up hope but got back to the ship with his ribs cracked and his mouth filled with blood and broken teeth. He took the wheel and fought water that was getting into the ship.

This shows, they were not willing to give in to danger but were ready to battle it. They faced the extremely cold night, struggling to pump out water, find direction and also work the radio. With no response to their desperate calls for help because they were in a distant comer of the world, they were still optimistic about finding lie Amsterdam and steered the ship towards that direction. Their optimism paid off” and they came out of a stressful situation.

Question 3.
What lessons do we learn from such hazardous experiences when we are face-to-face with death?
Answer:
One learns to be:

  • optimistic.
  • cooperative.
  • a team player.
  • alert to make the best of what one has.
  • enduring.

Question 4.
Why do you think people undertake such adventurous expeditions in spite of the risks involved?
Answer:
A human being’s life has become monotonous and mechanical. This deprives us of two important ingredients of happiness spontaneity and variety. Mechanical regularity produces discontentment as it is devoid of joy. Spontaneity and variety are needs of our instinctive nature that can only be satisfied by such adventures. Adventurous expeditions and other high level sports or activities break the monotony of modem life and provide opportunities to test our survival skills.

We’re Not Afraid to Die… If We Can All Be Together Thinking about language

Question 1.
We have come across words like ‘gale’ and ‘storm’ in the account. Here are two more words for ‘storm’: typhoon, cyclone. How many words does your language have for ‘storm’?
(Answers will vary).

Question 2.
Here are the terms for different kinds of vessels: yacht, boat, canoe, ship, steamer, schooner. Think of similar terms in your language.
(Answers will vary).

Question 3.
‘Catamaran’ is a kind of a boat. Do you know which Indian language this word is derived from? Check the dictionary.
Answer:
The word was coined in the early seventeenth century. It is derived from the Tamil word kattumaram, that means ‘tied wood’. Catamaran is a name applied to any craft having twin hulls. Originally, it denoted a form of Sailing and paddling raft employed on the coasts of India. In a catamaran, two similar or identical hulls are joined parallel to each other at some distance apart by beams or a platform.

Such crafts were highly developed in the Hawaiian, Marquesas, Tuamotu islands and Tahiti. Some of these crafts had hulls of unequal length. In recent years, the sailing catamaran has again become popular. The advantage of the catamaran is that great stability can be combined with lightness and low water resistance. In recent years, a triple-hull craft called a trimaran has also been developed.

Question 4.
Have you heard any boatmen’s songs? What kind of emotions do these songs usually express?
Answer:
Some famous boatmen songs include “Drunken Sailor” which describes a group of boatmen pondering over what to do with a drunken sailor early in the morning. “A Hundred Years Ago” pokes fun at the simplicity and foolishness of people that lived a hundred years ago, who thought pigs could fly and the moon was made of cheese. Both these songs are part of the genre referred to as shanty which are songs sung by boatman to amuse themselves during their work. Therefore the tone and lyrics are usually light hearted and amusing.

(Answers will vary).

We’re Not Afraid to Die… If We Can All Be Together Working with words

Question 1.
The following words used in the text as ship terminology are also commonly used in another sense. In what contexts would you use the other meaning?
knot ,stern, boom, hatch, anchor
I. Knot:

  • object made by tying: a usually hard, lump-shaped object formed when a strand of something such as a string or rope is interlaced with itself or another strand and pulled tight .
  • way of tying: a way of joining or securing lengths of rope, thread, or other strands by tying the material
    together or around itself
  • tangled mass: a tightly tangled mass of strands that are hard to separate
  • tight group: a number of people or things grouped closely together
  • tense feeling: a feeling of tightness or anxiety, for example, a knot in my stomach
  • close emotional tie: a deep bond, especially marriage
  • decoration: a piece of material such as ribbon or braid tied in a knot or bow and used as a decoration
  • problem: a difficult or complex problem
  • lump on tree: a lump on a tree trunk or branch
  • hard patch on tree: a hard patch on a tree out of which a branch or stem grows
  • dark whorl in timber: a hard, dark-coloured patch in cut wood at a point where a branch or stem formerly grew out of the tree
  • lump in body: a node, ganglion, lump, or swelling in the body
  • unit of speed: a unit of measurement for the speed at which a ship or aircraft travels, equivalent to one nautical mile per hour, approximately 1.85 kph/1.15 statute mph, symbol: kn
  • an indicator measuring ship’s speed: a division on a log line used to calculate the speed of a ship

II. Stern:

  • strict: rigid, strict, and uncompromising
  • forbidding: grim, austere, or forbidding in appearance

III. Boom (verb)

  • make loud deep sound: to make a cold, deep reverberating sound
  • utter something loudly: to say something in a loud, deep voice
  • experience significant increase in trade: to experience a significant expansion of business and investment, either across an economy or in a specific market, for example, Business is booming.

(noun)

  • loud deep sound: a loud deep reverberating sound
  • deep loud bird or animal noise: a deep, loud cry made by some birds and animals.
  • significant increase in amount: a significant increase in the amount of something such as a population level, for example, a population boom
  • significant increase in business: a significant expansion of business and investment, either across an economy or in a specific market, for example, a boom in sales

IV. Hatch

  • type of door: a door cut into the floor or ceiling of something, especially on a boat or an aircraft. It is lifted to provide access to the area below or above it. A hatch may also provide access to an attic or cellar in a building.
  • small hole between two rooms: a small connecting hole in a wall between two rooms, or the small doors that cover this hole, for example, an escape hatch

V. Anchor (noun)

  • device to hold ship in place: a heavy, traditionally double-hooked device for keeping a ship or floating object in place
  • device keeping object in place: any device that keeps an object in place
  • something dependable: somebody or something that provides stability
  • presenter of news programme: a presenter on a news programme, providing a link between the studio and reporters based outside
  • somebody positioned last: the team member who is responsible for the last leg in a relay race or who is at the back in a tug of war
  • climber’s rope attachment: a point to which a climber’s rope is fixed, for example, on a rock face or in ice

(Verb)

  • hold something in place: to hold something securely in place
  • put down anchor: to moor a ship by lowering its anchor so that it remains stationary in a place
  • present news programme: to be the presenter on a news programme

Question 2.
The following three compound words end in -ship. What does each of them mean? airship flagship lightship
Answer:
I. airship – a large aircraft without wings, used especially in the past and consisting of a large bag filled with
gas which is lighter than air and powered by engines. Passengers were carried in an enclosed structure hanging  below.

II. flagship –
(a) most important of group: the most important or prestigious among a group of similar and related things

  • the flagship of the hotel chain
  • the company’s flagship hotel

(b) commanding ship: the ship from which the admiral or unit commander controls the operation of a fleet
(c) main commercial ship: the main ship in a commercial fleet

III. Lightship – ship functioning as lighthouse: a ship with a bright, flashing light that functions as a lighthouse, especially one that is anchored in a place where a permanent structure would be impracticable

Question 3.
The following are the meanings listed in the dictionary against the phrase ‘take on’. In which meaning is it used in the third paragraph of the account:
Answer:
take on something: to begin to have a particular quality or appearance; to assume something
take somebody on: to employ somebody; to engage somebody to accept somebody as one’s opponent in a game, contest or conflict
take somebody/something on: to decide to do something; to allow something/somebody to enter, for example, a bus, plane or ship; to take something/somebody on board.
In the third paragraph, it means ‘to employ’ or ‘to engage’.

We’re Not Afraid to Die… If We Can All Be Together Things to do 

bow  – cabin – rudder – cockpit – stern – boom – mainsail – mast
NCERT Solutions for Class 11 English Hornbill Chapter 2 We’re Not Afraid to Die

2. Here is some information downloaded from the Internet on lie Amsterdam. You can view images of the isle if you go online.

3. Locate lie Amsterdam on the world map.
(Refer to Oxford Atlas and look for lie Amsterdam.).

NCERT Solutions for Class 11 English Snapshots Chapter 8 The Tale of Melon City

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Here we are providing NCERT Solutions for Class 11 English Snapshots Chapter 8 The Tale of Melon City. Students can get Class 11 English The Tale of Melon City NCERT Solutions, Questions and Answers designed by subject expert teachers.

The Tale of Melon City NCERT Solutions for Class 11 English Snapshots Chapter 8

The Tale of Melon City NCERT Text Book Questions and Answers

Question 1.
Narrate ‘The Tale of Melon City’ in your own words.
Answer:
Once, an impartial and mild-mannered King commissioned an arch to be built. After it was built, the king rode through the street and as he was crossing below the arch, his crown fell off as the arch was built too low.He felt that this was a dishonour and sentenced the chief of builders to be hung to death but the builder pleaded that it was not his fault but of the workers. The workers blamed the masons and the masons blamed the architect. The architect said that it was the king who had made certain changes in his plans. Hearing which, the king was infuriated.

He called for the wisest man in the country. The wisest man said it was the arch that had thrown the crown off, and it must be hanged but a councillor said that it would be a disgrace to hang something that touched the honourable head. By then, the crowd became restless and stated grumbling. The king noticed their mood and announced that the country wanted to see an execution and ordered for someone to be hanged immediately.

The loop in the rope was made ready and the people were measured, one by one, to see who would reach the noose. Finally, the man who reached the noose was the king himself and was hanged. After his execution, they spread the word that the next person to cross the city gate would decide the ruler of the kingdom. But the next man who crossed the city gate was a fool.

The guards asked him to decide who ought to be the king. The fool replied it ought to be “a melon”. The ministers crowned a melon and accepted it as their king. Now when the people are asked about their king being a melon, they say that the decision was because of “customary choice”.

Question 2.
What impression would you form of a state where the King was ‘just and placid’?
Answer:
The “just and placid” king was ruinous for the good of the state, and for himself. He was so mild-mannered that the people of the land influenced his decisions. The structural defect of an arch cost the king his life, and the people, the loss of a ruler. In his effort to be fair, he let go all the people who pleaded innocence and, being placid, he let himself be hung for no fault of his.

The people of the land, as foolish as their king, let a fool decide that a melon was to be crowned as the king and the people crowned it as their ruler. A state, if governed by factors other than reason, is likely to be doomed.

Question 3.
How, according to you, can peace and liberty be maintained in a state?
Answer:
Hints

  • judicious decisions (not being swayed by crowds)
  • respect for authority
  • democracy, not stupidity
  • respect for hierarchy
  • respect for reason

Question 4.
Suggest a few instances in the poem which highlight humour and irony.
Answer:
The poem is a light-hearted satire on the “just and placid” king. In his effort to be fair and mild-mannered, he invites his own doom. An arch was built and the king rides down the street “to edify spectators there”. When his crown was knocked off, a “frown appeared on his placid face”.

The king was easily placated by the offenders and the blame travelled from one person to the next, until it reached the king. The architect blamed the “placid” king, he “saw red” and “nearly, lost his head”. Living up to his reputation for being just, the king called for the wisest man.

The wise man was “carried to the Royal Court” as he could neither walk nor see. This served as the yardstick for wisdom. He ‘wisely’judged that the arch be hanged. The councillor disagreed as it would be disrespectful to hang something that had touched the royal head. The mild king called for an execution, guilty or not, to appease the crowd. This led to his execution. The “practical-minded” ministers found someone, if only the king, to be hanged to avoid the citizens turning “against the Crown”. They saved the crown by sacrificing the king.

They made another foolish proclamation that the next person that passed through the city gate would decide the next king. The idiot who crossed the gate chose a melon as the king and the ministers crowned it. The people of the land, proud of their “customary choice”, glorified their ‘melon king’ as he let them live in “peace and liberty”. The practice of letting the people do as they pleased suited them.

Question 5.
‘The Tale of Melon City’ has been narrated in a verse form. This is a unique style which lends extra charm to an ancient tale. Find similar examples in your language. Share them in the class.(Answers may vary.)
Answer:
Some examples of ancient and other tales that have been narrated in verse form in other languages include:
The Illiad- This is a long Greek Epic poem written in verse form by the famous Greek poet Homer, which describes the war that took place between the Greek and Trojan empires for the kingdom of Troy. Considered one of the most popular events in Greek mythology, this epic portrays the siege of Troy which lasted for over 10 years and ended with the Greeks emerging victorious.

Paradise Lost – This is a famous long Epic poem in blank verse written by the 17th century English poet John Milton. This narrates the first story from the book of Genesis in the Bible. The epic depicts the relationship between God and man in the Garden of Eden, followed by the temptation of Adam and Eve by Satan to eat the forbidden fruit, which led to the fall of man.

Night of the Scorpion – This poem written by Indian Jewish poet Nissim Ezekiel narrates a more recent story about a family in an Indian village. A child observers how their mother is stung by a scorpion and people try everything they can to help her fight the pain and fight death. Despite all attempts of medicine and prayer, she continues to struggle. However, in the morning she miraculously recovers, and is praised for her maternal courage of protecting her children from suffering a similar fate.

NCERT Solutions for Class 11 Biology Chapter 4 Animal Kingdom

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NCERT Solutions for Class 11 Biology Chapter 4 Animal Kingdom

These Solutions are part of NCERT Solutions for Class 11 Biology. Here we have given NCERT Solutions for Class 11 Biology Chapter 4 Animal Kingdom.

Question 1.
What are the difficulties that you would face in the classification of animals if common fundamental features are not taken into account?
Solution:
There are millions of living organisms with a vast variety of shapes, sizes,s, and forms. They occur in a variety of habitats. It is difficult to identify and describe them at random, so they are classified into various categories. For identification and classification, different types of classification are required. There are fundamental features common to various individuals in relation to the arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory, or reproductive systems, etc. These features are used in the classification of animals.

Question 2.
If you are given a specimen, what are the steps that you would follow to classify it?
Solution:
Classification of specimen deals according to a systematic plan on the basis of their v similarities, differences and relationship.
We will take the following steps
(i) Level or grade of organisation:
There are different types of cell which are organised into functional units of progressively increasing complexity. Such as acellular, cellular, tissue, organ and organ system.
(ii) Pattern in organ system :
There are different organ system in which specific group of organs work together to do a specific function. Such as digestive organs in digestive system. Respiratory organs in respiratory system, etc. in animal body.
(iii) Symmetry:
In animals, 4-types of symmetry are seen. These are spherical, radial, bilateral, Asymmetrical species are classified according to symmetry.
(iv) Diploblastic and triploblastic organisation: According to number of germ layers which differentiate at the time of gastrulation in developing embryo. Species are classified as diploblastic i.e. two germ layer and Triploblastic i.e. three germ layers.
(v) Body cavity or coelom:
According to types of coelom, species are classified into acoelom, pseudocoelom and eucoelom animals.
(vi) Segmentation:
Species are classified according to segmentation. It is of three types i.e. pseudometamerism or false segmentation, internal and external segmentation.
(vii) Notochord:
On the basis of notochord, animals or species are divided into chordates and non-chordates.
We will follow the above steps in classification of animal, then fair idea of that animal can be derived.

Question 3.
How useful is the study of the nature of body cavity and coelom in the classification of animals?
Solution:
Coelom is the gap between gut and body wall. Coelom is the characteristic feature of complex or higher animals while lower animals like Platyhelminthes are acoelomate. The absence of coelom indicates that the animal is yet to develop a functional division of labour to carry out various activities. So the coelom characterises complexity of the animals and represents organic evolution.
There are three types of coelom
(i) Acoelom – It means absence of body cavity which is due to the failure of mesoderm to cavitate during embryogency, so there is no coelom, no peritonium. ex-porifera, colenterata, etc.
(ii) Pseudocoelom — It means presence of coelom that develops from the blastocoel but not lined by mesoderm, ex-nematodes, etc.
(iii) Eucoelom – It means hue coelom, which is lined by mesoderm resulting in tube within -tube design.
ex- higher invertebrates, chordates, etc.

Question 4.
Distinguish between intracellular and extracellular digestion?
Solution:

  1. Intracellular digestion takes place inside the cells by cellular enzymes, which are secreted by the surrounding cytoplasm into the food vacuole and the digestive products are then diffused in cytoplasm.
  2. It mainly occurs in unicellular organism and also is a less efficient method.
  3. Extracellular digestion occurs with the help of digestive enzymes poured into gastrovascular cavity by secretory cells and then the digestive products are diffused across the intestinal wall into various parts of the body.
  4. It mainly occurs in multicellular organisms and is more efficient.

Question 5.
What is the difference between direct and indirect development?
Solution:
In oviparous animals, the newly hatched young may resemble the adult. Such a development is called direct development. In some cases, the young hatched from eggs do not resemble the adult. These young are called larvae, nymphs, or naiad. They lead an independent life for some period and finally undergo important change to become adults. These changes from larvae to adults are called metamorphosis and such a development is called indirect development.

Question 6.
What are the peculiar features that you find in parasitic Platyhelminthes?
Solution:
Members of Platyhelminthes possess the following characteristics.

  • These are mostly endoparasites of animals including human.
  • Hook and suckers are present for attachment to host body.
  • They absorb nutrient from the host directly through their body surface.
  • These are free-living, parasitic forms. Tissue, organ, grade of body organization is seen.
  • The digestive tract is incomplete or absent.
  • Respiration is anaerobic.
  • Reproductive system of parasitic forms is highly developed with enormous power of reproduction.
  • Well defined excretory organs such as flame cells are present.

Question 7.
What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Solution:
The phylum Arthropoda constitutes the largest group of animals which include many economically important insects. Over two-thirds of all named species on earth are arthropods. They have an organ-system level of, body organization. They are bilaterally symmetrical, triploblastic, segmented, and acoelomate animals. The body of arthropods is covered by a chitinous cuticle which forms the exoskeleton. The body segments are fused to form the head, thorax, and abdomen. They have jointed appendages. The appendages are variously modified to form antennae, mouthparts, pincers, or walking legs.

The digestive system is complete. Respiratory organs are gills, book-gills, book lungs, or tracheal systems. The circulatory system is open type. The nervous system is almost similar to that of the annelids. Sensory organs include antennae for perceiving odor, receptors for taste, eyes, statocysts or balance organs, and sound receptors. Excretion takes place through green glands or malpighian tubules. They are mostly dioecious, Reproduction is sexual. Fertilization is usually internal. They are mostly oviparous. Development may be direct or indirect, passing through many larval stages. The process of transformation of a larva into an adult is called metamorphosis.

Question 8.
Water vascular system is the characteristic of which group of the following:
(a) Porifera
(b) Ctenophora
(c) Echinodermata
(d) Chordata
Solution:
Echinodermata – Its vascular system with tube feet helps in locomotion. A perforated plate , madreporite, permits entry of water into ambulacral system which also help in food and gas transport system.

Question 9.
“All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.
Solution:
The members of subphylum Vertebrata possess notochord during the embryonic period, which is replaced by a cartilaginous or bony vertebral column in the adult. Thus, all vertebrates are chordates but all chordates are not vertebrates. Besides the three basic chordate characters, vertebrates have a ventral muscular heart with two, three, or four chambers, kidneys for excretion and osmoregulation, and paired appendages which may be fins or limbs.

Question 10.
How important is the presence of an air bladder in Pisces?
Solution:
The class Osteichthyes possesses Air bladder. It helps the organism in regulating buoyancy. If the air bladder were absent the animal had to swim constantly to avoid sinking.

Question 11.
What are the modifications that are observed in birds that help them fly?
Solution:
The birds are adopted for flying by reducing the weight and other modifications which are as follows :

  • The forelimb modified into wings to assist in flight.
  • Left ovary absent or reduced
  • Presence of pneumatic or hollow bones for making a lightweight skeleton.
  • The aerodynamic body helps in flying.
  • Excretion of urine and faeces occurs through single opening.

Question 12.
Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
Solution:
Normally the number of eggs produced by oviparous is greater than the number of young ones by viviparous. The development of young ones is oviparous takes place outside the mother whereas in the viviparous the development of the embryo takes place inside the uterus of the mother hence a viviparous mother can have very less number of embryos at a time in her uterus. Whereas oviparous mothers have no need to feed their young ones (embryos) until hatched. Hence, largest in number.

Question 13.
13. Segmentation in the body is first observed in which of the following:
(a) Platyhelminthes
(b) Aschelminthes
(c) Annelida
(d) Arthropoda
Solution:
(c) Annelida.

Question 14.
Match the following:
(a) Operculum      (i) Ctenophora
(b) Parapodia       (ii) Mollusca
(c) Scales          (iii) Porifera
(d) Comb plates    (iv) Reptilia
(e) Radula          (v) Annelida
(f) Hair            (vi) Cyclostomata and Chondrichthyes
(g) Choanocytes  (vii) Mammalia
(h) Gill slits      (viii) Osteichthyes
Solution:
(a) Operculum            (viii) Porifera
(b) Parapodia            (v) Annelida
(c) Scales               (iv) Reptilia
(d) Comb Plates    (i) Ctenophora
(e) Radula               (ii) Mollusca
(f) Hair                 (vii) Mammalia
(g) Choanocytes    (iii) Porifera
(h) Gill slits           (v) Cyclostomata and Chondrichthys

Question 15.
Prepare a list of some animals that are found
parasitic on human beings.
Solution:

  • Taenia (Tapeworm)
  • Fasciola (liver fluke)
  • Planaria
  • Echinococcus
  • Pheretima (Earthworm)
  • Hirudinaria (leech)

VERY SHORT ANSWER QUESTIONS

Question 1.
What is common name of Euspongia ?
Solution:
Bath sponge

Question 2.
Name the class which is characterised by pneumatic bones.
Solution:
Aves

Question 3.
Give the characteristic feature of Echinodermata.
Solution:
Water vascular system

Question 4.
Name the phyla which shows metamerism.
Solution:
Annelida, Arthropoda and Chordata.

Question 5.
Name two animal groups with incomplete digestive tract.
Solution:
Cnidariaandplatyhelminthes.

Question 6.
Name a fresh water sponge and coelenterate.
Solution:
Spongilla and Hydra

Question 7.
What is radula ?
Solution:
Rasping organ of molluscs.

Question 8.
Name two characteristic organs of chordates.
Solution:
Notochord and gill slits.

Question 9.
To which phyla Balanoglossus belong ?
Solution:
Hemichordata

Question 10.
Name two flightless birds.
Solution:
Ostrich, Kiwi

Question 11.
Give one example each of ectothermal and endothermal animals.
Solution:
Reptiles, mammals.

Question 12.
Give one example of cephalochordata.
Solution:
Branchiostoma (Amphioxus)

Question 13.
Why do lampreys and snakes lack girdles ?
Solution:
Due to lack of limbs.

Question 14.
What is the difference between epidermis of invertebrates and vertebrates ?
Solution:
Epidermis is a stratified epithelium in vertebrates and a simple epithelium in invertebrates.

Question 15.
Mention modification of coelom in echinoderms.
Solution:
A part of the echinoderm coelom is modified into a water-vascular system for help in locomotion.

Question 16.
What are setae ?
Solution:
Locomotive organs of phylum annelida.

Question 17.
What are endothermic animals ?
Solution:
Endothermic animals (birds and mammals) generate most of their body heat by metabolism.

Question 18.
Why is the Ornithorhynchus considered an 3 exceptional mammal ?
Solution:
Ornithorhynchus, though a mammal, lays egg and has a cloacal aperture.

SHORT ANSWER QUESTIONS

Question 1.
What are pneumatic bones ? Where do you find them?
Solution:
Bones having air spaces in them are called pneumatic bones. Birds have such types of bones to make body light for flying.

Question 2.
How do earthworm and leech differ with regard to their coelom ?
Solution:
Coelom is spacious in earthworm and greatly reduced in leech by formation of botryoidal tissue in it.

Question 3.
Cite unique features of nematodes.
Solution:
Syncytial epidermis, pseudocoel, non-muscular intestine and body wall musculature of longitudinal fibres only.

Question 4.
What is marsupium ?
Solution:
Marsupium is pouch on the females belly for rearing the young one in metatherian mammals. e.g. Kangaroo.

Question 5.
Why is coelentron called gastrovascular cavity ?
Solution:
It is a cavity in which both digestion and circulation occur.

Question 6.
What is the fate of notochord in higher chordate ?
Solution:
Notochord is replaced by vertebral column partly or fully in chordates.

Question 7.
State the two types of fishes. Give their examples.
Solution:
The two types of fishes are
(1) Chrondrichthyes example Trygon, electric ray
(2) Osteichthyes example Rohu, Sea horse

Question 8.
What is metamerism?
Solution:
It is a phenomenen found in organisms like earth worm that they have their bodies segmented and this parttem is called metameric segmentation.

Question 9.
Why are Urochordates called Tunicata?
Solution:
As the adult bodies of Urochordata is covered by a tunic like cover to these are called Tunicata.

Question 10.
Give an example of an organism showing.
(1) Radial symmetry
(2) Bilateral symmetry
Solution:
Radial symmetry: Star fish Bilateral symmetry: Octopus, men.

LONG ANSWER QUESTIONS

Question 1.
(i) What are different symmetry that exists in animal kingdom.
(ii) Distinguish between diploblastic and triploblastic
Solution:
(a) Asymmetrical symmetry
I. In many animals the body can not be divided in two equal halves on any plane.
II. Ex. Amoeba being irregular in shape, some sponges with various branching. Gastropod molluscs (snails, conch) have no symmetry due to torsion in embryonic stage.
(b) Radial symmetry
I. Any plane passing through a central axis of the body divides the organism into two identical halves.
II. Examples are Coelentrates, ctenophores and echinoderms.
(c) Bilateral symmetry
I. In most animals body can be divided into two equal halves on only one plane, hence body has left and right sides front and rear (back) sides; anterior and posterior ends; dorsal and ventral sides.
II. Their advance symmetry and such animals are most mobile.
Diploblastic animals: Animals in which cells are arranged in two embryonic layers, an external ectoderm and internal endoderm are called diploblastic animals.
Triploblastic animals: Animals in which developing embryo has the third germinal layers, mesoderm, in between the ectoderm and endoderm are called triploblastic animals.

Question 2.
Describe economic importance of the largest phylum.
Solution:
The largest phylum is Arhtropoda and its economic importance is as follows:

  • They are major agents for cross pollination. Insects, like butterflies and honey bee facilitate cross pollination.
  • Honey is an important food for human.
  • Many crustaceans, like lobsters and prawns are art of cuisine around the world.
  • The red dye cochineal, produced from a Central American species of insect, was economically important to the Aztecs and Mayans.
  • The blood of horseshoe crabs a clotting agent Limulus Amebocyte Lysate which is now used to test that antibiotics and kidney machines are free of dangerous bacteria, and to detect spinal meningitis and some cancers.
  • Maggots of housefly are used to treat those wounds which take time to heal because of absence of blood supply.
  • The relative simplicity of the arthropods ’ body plan, allowing them to move on a variety of surfaces both on land and in water, have made them useful as models for robotics.
  • They are carriers of many human parasite causing diseases like malaria, filaria and sleeping sickness.
  • Cockroaches are one of the major nuisance as they contaminate food in kitchens.
  • Termites are major causes of playing havoc with wooden furnitures.
  • Scorpions are known for their deadly sting, which can kill human and livestock.

Question 3.
What are the peculiar characters of Aschelminthes?
Solution:
(i) The body of aschelminthes is circular in cross-section, hence named round worms.
(ii) They may be free living, a quatic and terrestrial or parasitic in plants and animals.
(iii) They have organ-system level of body organisation.
(iv) They are bilaterally symmetrical, triploblastic andpseudocoelomate.
(v) Alimentary canal is complete with well developed muscular pharynx.
(vi) An excretory tube removes body waste from the body cavity through the excretory pore.
(vii) Sexes are separate (dioecious), i.e., males and females are distinct. Often females are longer than males.
(viii) Fertilisation is internal and development may be direct or indirect.
(ix) Examples. Ascaris (Round worm), Wuchereria (Filaria worm), Ancylostoma (Hookworm).

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