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CLASS XI CBSE BIOLOGY Directions: (Q. Nos. 91-101) In the following questions, more than one of the answers given may be correct. Select the correct answers and mark them according to the codes given below: Codes: (a) 1, 2 and 3 are correct (b) 1 and 2 are correct (c) 2 and 4 are correct (d) 1 and 3 are correct Set – A-91 | B-110 91. The permanent teeth (1) are of four types-incisors, canines, premolars and molars (2) begin to replace the milk teeth in the 6th year of age (3) are 32 and usually completed by 18-25 years (4) are 20 in children Sol: A Set – A-92 | B-111 92. Which of the following are correct for pharynx? (1) (2) It is a junction of buccal cavity, nasal chamber, Eustachian tube, trachea and breathing It is a common passage in swallowing food and breathing 24 CLASS XI CBSE (3) (4) It is the aperture, which leads into the oesophagus It is the structure, which allows air to enter into trachea Sol: B The pharynx (plural: pharynges) is the part of the throat that is behind the mouth and nasal cavity and above the oesophagus and the larynx, or the tubes going down to the stomach and the lungs. The pharynx is an organ found in vertebrates and invertebrates, though the structure is not universally the same across all of those species. In humans the pharynx is part of the digestive system and also of the conducting zone of the respiratory system. (The conducting zone also includes the nose, larynx, trachea, bronchi, and bronchioles, and their function is to filter, warm, and moisten air and conduct it into the lungs.[1]) The pharynx makes up the part of the throat situated immediately behind the nasal cavity, behind the mouth and above the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx, the oropharynx and the laryngopharynx. It is also important in vocalization. Set – A-93 | B-112 93. Which of the following are the functions of intestinal juice and its enzymes? Erepsin (1) Polypeptides + Oligopeptides Amino peptidase Enterokinase (2) Trypsinogen (inactive) → Phospholipase (3) Phospholipids → Monoglycerides (4) Proteins + Peptones Amino acids Trypsin (active) Phosphorus + Fatty acids + Glycerol + Pepsin pH−13 Polypeptides + Oligopeptides Sol: A Both pancreatic juice and intestinal juice are poured into small intestine. Pancreatic juice contains trypsinogen, chymotrypsinogen, carboxypeptidases, lipases, amylases, DNAases and RNAases. All these enzymes of pancreatic juice can act only in the alkaline medium. This 25 CLASS XI CBSE change in the medium of food, from acidic to alkaline, is done by the bile juice. Therefore, bile juice acts on the food before the action of pancreatic juice. In the intestinal lumen, pancreatic and intestinal juices mix together. Then a protease of intestinal juice, called Enteropeptidase or Enterokinase acts in coordination with pancreatic proteases. This enterokinase converts inactive trypsinogen into active trypsin. In predatory animals, trypsins can hydrolyse fibrinogen of blood into fibrin leading to blood coagulation. But it is unable to bring about coagulation of milk. The inactive Chymotrypsinogen is activated to chymotrypsin by trypsin. Chymotrypsins can hydrolyse casein into paracasein, which then coagulates to form calcium paracaseinate. But it acts in the alkaline medium. Chymotrypsin acts on other proteins and converts them into peptides. Carboxypeptidase hydrolyses the terminal carboxyl groups from peptide bonds to release the last amino acids from the peptides thus making the peptide shorter. The intestinal juice contains aminopeptidases and dipeptidases; and enterokinase or enteropeptidase. Out of these enterokinase activates the trypsinogen. Aminopeptidase hydrolyses the terminal amino group from peptide bonds to release the last amino acid from the peptides thus making the peptide shorter. Dipeptidase acts on dipeptides to release the individual amino acids. Fat digestion starts only when the food reaches the small intestine. It starts with the action of bile juice from liver. Bile juice contains bile salts, which are secreted by the liver in the bile. Bile salts break down the bigger molecules of fat globules into smaller droplets by reducing the surface tension of fat droplets. This process is known as emulsification of fats. Lipase is the enzyme that acts on emulsified fats. It is present both in the pancreatic juice and intestinal juice. Lipase converts emulsified fats into diglycerides and monoglycerides releasing fatty acids at each step. At the end of digestion, all fats are converted into fatty acids, glycerol and monoglycerides. Set – A-94 | B-113 94. Liver (1) makes the medium slightly acidic for the action of its enzyme (2) functions as a store house for blood and regulates blood volume 26 CLASS XI CBSE (3) absorbs water from undigested food (4) is the site of detoxification of different toxic substances Sol: C Liver: It is the largest gland of the body lying immediately below the diaphragm in the right upper part of abdomen. The cells of the liver (hepatic cells) produce bile juice that contains bile pigments and bile salts. These bile salts help in the digestion and absorption of fats. Bile juice does not contain any enzyme. Bile juice flows out of the liver through hepatic ducts forming the common bile duct that opens into the duodenum (when the food is present in the duodenum). When there is no food in the duodenum, then bile juice is stored in the gall bladder. The gall bladder is a small elongated, muscular sac below the liver. When the food comes into duodenum, it contracts to release the bile juice. Set – A-95 | B-114 95. Which of the following are correct for absorption from the stomach? (1) The substances normally absorbed from the stomach are some water, glucose and considerable amounts of alcohol (2) The substances are absorbed through the walls of the stomach into the venous circulation (3) There is no absorption but a few drugs may be absorbed (4) Some amount of vitamins are absorbed Sol: B Although the absorption is mainly a function of the small intestine, some absorption of certain small molecules nevertheless does occur in the stomach through its lining. This includes: Water, if the body is dehydrated Medication, like aspirin Amino acids 10–20% of ingested ethanol (e.g. from alcoholic beverages) Caffeine To a small extent water-soluble vitamins (most are absorbed in the small intestine) The parietal cells of the stomach are responsible for producing intrinsic factor, which is necessary for the absorption of vitamin B12. B12 is used in cellular metabolism and is necessary for the production of red blood cells, and the functioning of the nervous system. Alcohol (ethanol) is absorbed slowly from the stomach and rapidly from the small intestine, and the rate of its absorption depends on the rate of gastric emptying. When gastric emptying is fast, the absorption of alcohol is fast. When gastric emptying is slow the absorption of alcohol is delayed and peak blood alcohol concentrations are reduced. Set – A-96 | B-115 96. The diffusion of bicarbonate ions from RBC into plasma and of chloride ions from plasma into RBC to maintain ionic balance between RBC and plasma is known as 27 CLASS XI CBSE (1) Henry’s law (3) Charle’s law (2) Chloride shift (4) Hamburger’s phenomenon Sol: C Set – A-97 | B-116 97. The mucus produced by the goblet cells (1) moistens the incoming air (2) traps the finest dust particles (3) filter out largest dust particles (4) warm the incoming air Sol: B 28 CLASS XI CBSE Goblet cells are found scattered among the epithelial lining of organs, such as the intestinal and respiratory tracts. They are found inside thetrachea, bronchi, and larger bronchioles in the respiratory tract, small intestines, the large intestine, and conjunctiva in the upper eyelid. Set – A-98| B-117 98. The lobes of left lung are called (1) left anterior (3) left posterior (2) anterior azygous (4) posterior azygous 29 CLASS XI CBSE Sol: D 30 CLASS XI CBSE Set – A-99 | B-118 99. The respiratory system in humans and other lung-breathing vertebrates can be divided into (1) conducting portion (3) upper portion (2) gas exchange portion (4) lower portion Sol: B 31 CLASS XI CBSE Set – A-100 | B-119 100. When blood is mixed with cyanide (to stop carbonic anhydrase activity) the rate of……….and………..will show………. (1) absorption (3) dissociation of CO2 (2) adsorption (4) association of CO2 Sol: A Set – A-101 | B-120 101. Certain bacteria that cause bronchitis are (1) Streptococcus pneumoniae (3) Yersinia pestis (2) Haemophilus influenza (4) Clostridium tetani Sol: B Acute bronchitis. Bacteria can cause bronchitis in people with underlying health problems. Mycoplasma pneumoniae, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Bordetella pertussis are most commonly involved. Set – A-102 | B-101 102. Where do certain symbiotic microorganisms normally occur in human body? (a) Caecum (c) Vermiform appendix and rectum (b)Oral lining and tongue surface (d) Duodenum Duodenum The duodenum is a hollowed tube that is situated between the stomach and the jejunum. The duodenum is the shortest section of the small intestine; it is 26cm long, on average. It is mostly responsible for digesting chyme, the food bolus that was created by the churning motion of the stomach. Since it doesn’t have the thick mucus lining like the stomach, the duodenum cannot tolerate the low pH introduced by the chyme. In order to neutralize the pH, the liver secretes bile and pancreas secretes bicarbonate into the duodenum and brings the pH of duodenum up to around 5 and 6 range, a much more tolerable pH for protein and enzymes to function. Enzymes such as lipase, trypsin and chymotrypsin are also secreted into the duodenum to aid digestion. The bacterial density in this section of the small intestine 32 CLASS XI CBSE reaches 101 to 103 CFU (Colony Forming Units) /mL and flourishes with gram-positive cocci and rods. The intestinal tract of human body has ten times as many microbial organisms than the rest of the body cells in the body. There are up to 100,000 primarily aerobic organisms per milliliter found in the small intestine, and there are at least 500 bacterial species present inside the intestinal tract . The bacterial environment of the jejunum, the middle section of the small intestine located after the duodenum, consists mainly of grampositive Streptococci and Lactobacilli . Research done on several healthy volunteers showed the presence of Streptococci, Lactobacilli, Staphylococci, and fungi in the intestinal tract . In the ileocaecal valve, Bacteroides and coliform bacteria are the dominant bacteria present there, in addition to anaerobic Lactobacilli . In the ileum, the last section of the small intestine, the bacterial presence is varied, due to the “backwash contamination of the colon” . Set – A-103 | B-102 103. Which of the following is a gastrointestine hormone? (a) Prolactin (b) Enterogastrone (c) GH (d) FSH An enterogastrone is any hormone secreted by the mucosa of the duodenum in the lower gastrointestinal tract in response to dietary lipids that inhibits the caudal (or "forward, analward") motion of the contents of chyme. Examples include: secretin cholecystokinin gastric inhibitory peptide Set – A-104 | B-103 104. The pH of stomach is 1.6, then which enzyme will digest protein? (a) Trypsin (b) Pepsin (c) Amylase 33 (d) Erypsin CLASS XI CBSE The stomach and protein digestion Protein digestion begins in the stomach, and this is a “preparation stage” compared to the events that occur in the duodenum.The presence of food in the stomach stimulates G cells of the mucosa of the gastric antrum and proximal duodenum to produce and release the hormone gastrin into the bloodstream. The hormone stimulates the parietal cells of the proper gastric glands, localized mostly at the bottom of the organ, to produce and secrete hydrochloric acid into the stomach (parietal cells also produce the intrinsic factor, a protein that binds vitamin B12, preventing its destruction and allowing it to be absorbed). In the proper gastric glands you also found: mucous neck cells, that produce mucus; chief cells, that release pepsinogen. All of these substances, together with others such as potassium ions and the gastric lipase, are present in the gastric juice, which has a pH that ranges between 1 and 2.5. Due to its low pH, the gastric juice has an antiseptic action, killing most bacteria and other foreign cells, and a denaturing effect, as it breaks the noncovalent bonds that maintain the native structure of proteins. This denaturing effect facilitates the access of intestinal protease to peptide bonds, like the heating during cooking. Some proteins rich in disulfide bonds, such as keratins, are resistant to denaturation by low pH, and hence difficult to digest. On the contrary, most of the globular proteins are almost completely hydrolyzed into constituent amino acids. Finally, the low pH of the gastric juice activates pepsinogen, a zymogen, to pepsin, the first enzyme involved in protein digestion. Set – A-105 | B-104 105. Ptyalin is inactivated by a component of gastric juice known as (a) pepsin (b) mucus (c) renin 34 (d) HCl CLASS XI CBSE Set – A-106 | B-105 106. Kupffer’s cells are (a) phagocytic (b) non-phagocytic (c) myosin (d) fibrin Kupffer cells are macrophages which are located inside the sinusoids of liver and are supposed to be macrophages. These cells account for the standardized monocyte or macrophage specialization such as receptor mediated phagocytosis or lysosomal digestion. This Kupffer cell population of macrophages not only cleans bacteria from the portal blood stream which is the bad intestinal blood but it also removes the dead RBCs and help in the recycling of hemoglobin. This job is executed by the macrophages along with spleen. Kupffer You do not have access to view this node have close association with liver’s endothelial lining. Kupffer cells are placed draping the liver sinusoids and hence it is difficult to differentiate them from the endothelial You do not have access to view this node. Set – A-107 | B-106 107. Complete the equation. Nucleases Nucleic acids → → Nucleotides ……… (a) Monoglycerides (b) Diglycerides (c) Disaccharides (d) Nucleosides Set – A-108 | B-107 108. The pH of the digestive juices within the human small intestine is between 7.5 and 8.5. This environment is slightly (a) basic (b) acidic (c) neutral 35 (d) None of these CLASS XI CBSE Set – A-109 | B-108 109. Which one of the following pairs of the kind of cells and their secretion of correctly matched? (a) Oxyntic cells (b) Alpha cells of islets of Langerhans (c) Kupffer’s cells (d) Sebaceous glands --- A secretion with pH between 2.0 and 3.0 --- Secretion that decreases blood sugar level --- A digestive enzyme that hydrolyses nucleic acids --- A secretion that evaporates for cooling 36 CLASS XI CBSE Parietal cells (also known as oxyntic or delomorphous cells), are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. Set – A-110 | B-109 110. Rennin converts (a) casein to caesinagen (c) casein to procaesinogen (b) case to procaesin (d) procaesin to casein Rennin, also known as chymosin, is an enzyme that can be easily found in the rennet. It is usually produced by the 4thstomach chamber of the cows, called abomasum. Infants have gastric chief cells that produce rennin in order to clot the milk and promote a much better absorption. Alternatively, the bovine rennin is produced in K. lactis, Aspergillus niger var awamori and E. coli. Although it’s not active, this enzyme can also be found in the human body on the chromosome 1. 37 CLASS XI CBSE Rennin enzyme is included in the protease family and along with pepsin it’s the only enzyme that can be found in the stomach. In its inactive form, rennin is known as prorennin. When milk is consumed, the stomach produces hydrochloric acid. This immediately connects with the prorennin and activates it, forcing the enzyme to produce beneficial rennin. Milk contains the caseinogen protein that include: kappa-casein beta-casein alpha-s2 alpha-s1 molecules rennin is beneficial for coagulating or curdling the milk. It breaks down the milk into whey or liquid and semisolid substance. Thus, the stomach can digest and absorb milk proteins, which is extremely important for the human body. In case the stomach doesn’t produce enough rennin, the milk is not digested properly and the calcium cannot be absorbed in the bones and body. So, young mammals are the only ones that can produce rennin enzymes. Immediately after birth, their stomach secrets high doses of rennin, but with age the production ends and the pepsin enzyme becomes more active and important. Rennin is also used in the dairy industry for the making of cheese. Set – A-111 | B-91 111. Magnesium is most abundant in (a) milk (b) meat (c) fish Some of the major functions that require magnesium are: Protein synthesis Nerve function Blood sugar control Neurotransmitter release Blood pressure regulation Energy metabolism Production of the antioxidant glutathione 38 (d) soya bean CLASS XI CBSE Set – A-112 | B-92 112. Skin is an accessory organ of respiration in (a) human (b) frog (c) rabbit (d) lizard Set – A-113 | B-93 113. When the oxygen supply to the tissue in inadequate, the condition is (a) dyspnea (b) hypoxia (c) asphyxia (d) apnea Hypoxia is a condition characterized by an inadequate supply of oxygen in the blood due to reduction of partial pressure of oxygen(at high altitudes), inadequate oxygen transportation and inability of the body tissues to use oxygen due to some pathology(such as anemia) Hypoxia is defined as a condition where body tissues are not adequately oxygenated. This condition is mostly due to an insufficient concentration of oxygen in the blood. This will ultimately result in an impairment of the metabolic activities taking place in the body, giving rise to several compensatory signs and symptoms as follows. An increase in the heart rate, myocardial contractility, and cardiac output. Shortness of breath, Wheezing, Sweating Cyanosis or bluish discoloration of mucosal membranes due to poor peripheral blood supply. Other changes of the skin color, ranging from blue to cherry red depending on the etiology. Hypoxia can be categorized as Local – affecting a specific area of the body 39 CLASS XI CBSE Generalized – Involving the whole body which may be sometimes referred to as Anoxia (a complete deprivation of oxygen-rich blood supply, throughout the body. Causes of Hypoxia: Hypoxia can be caused by several different conditions such as, Anaemia, which is a condition caused by a reduced amount of functional hemoglobin, reducing the oxygen-carrying capacity of blood, Heart diseases and lung diseases such as COPD, Emphysema, Bronchitis, Pulmonary edema Carbon monoxide poisoning – This gas which has a higher potential of getting attached to hemoglobin when compared to that of oxygen can give rise to heart failure, cardiac arrest or myocardial infarction. Set – A-114 | B-94 114. After forceful inspiration, the amount of air that can be breathed out by maximum forced expiration is equal to (a) Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV) + Tidal Volume (TV) + Residual Volume (RV) (b) IRV + RV + ERV (c) IRV + TV + ERV (d) TV + RV + ERV Forced expiratory volume (FEV) measures how much air a person can exhale during a forced breath. The amount of air exhaled may be measured during the first (FEV1), second (FEV2), and/or third seconds (FEV3) of the forced breath. Forced vital capacity (FVC) is the total amount of air exhaled during the FEV test. Set – A-115 | B-95 115. Amount of oxygen supplied by 100 mL arterial blood while passing through the tissues is (a) 0.4-0.6 mL (b) 4-6 mL (c) 14-15 mL (d) 19-20 mL Set – A-116 | B-96 116. The volume of ‘anatomical dead space’ air is normally (a) 230 mL (b) 210 mL (c) 190 mL 40 (d) 150 mL CLASS XI CBSE Anatomic dead space is the total volume of the conducting airways from the nose or mouth down to the level of the terminal bronchioles, and is about 150 ml on the average in humans. The anatomic dead space fills with inspired air at the end of each inspiration, but this air is exhaled unchanged. Set – A-117 | B-97 117. Arrange the following in the order of increasing volume. I. Tidal volume III. Expiratory reserve volume II. Residual volume IV. Vital capacity (a) I < II < III < IV (b) I < III < II < IV (c) I < IV < III < II (d) I < IV < II < III 41 CLASS XI CBSE Set – A-118 | B-98 118. Mammalian lungs have an enormous number of minute alveoli (air sacs). This is to allow (a) more space for increasing the volume of inspired air (b) more surface area for diffusion of gases (c) more spongy texture for keeping lungs in proper shape (d) more nerve supply to keep the lungs working 42 CLASS XI CBSE Set – A-191 | B-99 119. Which of the following is a respiratory disease? (a) Polio (b) Arthritis (c) Asthma (d) Cancer Set – A-120 | B-100 120. After a deep inspiration and maximum expiration, the capacity of lung is known as (a) vital capacity (b) tidal volume (c) IRV 43 (d) ERV