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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
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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
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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
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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
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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
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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
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CLASS XI CBSE
Sol: D
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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
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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
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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
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(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
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(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
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(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
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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.
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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
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(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
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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
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(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
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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
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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
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(d) ERV