CLASS - XI BIOLOGY (Breathing and Exchange of gases) [ANSWERS]
Ans 01. Pressure contributed by an individual gas in a mixture of gases is called partial pressure of gas and it is represented as PO2 for O2 and PCO2 for CO2.
Ans 02. Haemocyanin and haemoerythrin.
Ans 03. Alveolar air – The air present in the alveoli.
Inspired air – The amount of air inspired at a time.
Ans 04. The contraction of the external intercoastals muscles & diaphragm increases the volume of the thoracic cavity lowers the pressure in the lungs. To fill up the gap, the fresh air reaches to the lungs resulting in the inspiration.
The relaxation of the inspiratory muscles decreases the volume of the thoracic cavity and subsequently, pressure in the lungs increase. To equalize this pressure, the air from the lungs rushes out through the respiratory passage to bring about expiration.
Ans 05. Erythrocytes lack mitochondria and respiratory enzymes to perform the process of aerobic respiration. Therefore, they undergo aerobic respiration to carry out anaerobic metabolism only.
Ans 06. Passage of air which contains oxygen:
Inhalation of fresh air → trachea → bronchi → lungs → alveoli → diffusion of O2
into blood (RBC) → formation of oxygemoglobin → some in plasma → pulmonary vein → carry it to heart → left auricle → to ventricle → Dorsal aorta → Carotid artery to the brain dissociation of oxyhaemoglobin, O2 supplied to the tissue, partial pressure of O2 facilitates diffusion.
Ans 07. Hypoxia – It is a condition of oxygen shortage in the tissues. It is 2 kinds – artificial hypoxia and anaemic hypoxia.
Artificial hypoxia – It is the result of shortage of air over 2400m altitudes. The mountain sickness is caused by headache, dizziness, nausea, vomiting, mental fatigue and breathless mess etc.
Anaemic hypoxia – results due to reduced O2 capacity of blood due to less content of Hb or carbon monoxide poisoning.
Ans 08. Respiratory centre located in floor of the medulla oblongata of the brain controls respiration. The centre is bilateral and its two halves which are connected together by commissural neurons. The sides of this centre are connected with motor respiratory neuron. The nerve cells of the centre are connected with the breathing apparatus forming a reflex arc. These nerve cells are secretive to chemical composition of blood. Half of the respiratory centre is an inspiratory centre and expiratory centre. It is believed that the inspiratory centre work in normal breathing and expiratory centre during other conditions like coughing, sneezing and laughing. These two centers control the entire breathing in man with his knowing about it. Dorsal respiratory group, ventral respiratory group and pneumoptaxic groups act as respiration centers in the brain.
Neumotaxic centre is located dorsally in upper pons. It transmits signals to inspiratory area. It controls the switch off point of inspiration.
Ans 09. Transport of CO2 in the blood.
(i) In the dissolved form
About 5 – 7 % of carbon – dioxide is transported in dissolved form in the plasma of blood.
(ii) In the form of bicarbonate.
The remaining part of carbon dioxide enters the erythrocytes, where it reacts with the water to form carbonic acid (H2 CO3) ; this reaction is catalysed by carbonic anhydrase....
o Carbonic acid immediately dissociates into hydrogen ions (H+) and bicarbonate (HCO3-)
o These H+ ions combine with haemoglobin, after the oxyglobin (KHbO2) dissociates to liberate the oxygen ; as a result haemoglobinic acid (H.Hb) is formed.
o The majority of bicarbonate ions (HCO-3) diffuses out of the erythrocytes into the plasma, following a concentration gradient.
o In response, chloride ions (Cl-) diffuse from the plasma into the erythrocytes (Chloride shift) and electrical neutrality is maintained.
o The chloride ions combine with potassium to form potassium chloride.
o In the plasma the bicarbonate ions combine with sodium and transported as sodium bicarbonate (NaHCO3)
o Nearly 70% of the carbon dioxide is transported in this form.
(iii) In the form of carbaminohaemoglobin
o Same amount of CO2 reacts with the amine radicals (NH2+) of haenoglobin and form carbaminohaemoglobin (HbCO2) molecule.
o About 23% of carbon – dioxide is transported in this form.
CBSE TEST PAPER-02
CLASS - XI BIOLOGY (Breathing and Exchange of Gases)
1. Define vital capacity. [1]
2. What is the role of carbonic anhydrase in RBC’s? [1]
3. What is carbamino haemoglobin? [1]
4. What is chloride shift? Explain. [2]
5. Explain briefly the first step is respiration? [2]
6. Write a note on bronchitis and its prevention. [2]
7. Differentiate between vital lung capacity and total lung capacity. [3]
8. Explain the mechanism of breathing in humans. [3]
9. Describe in brief the respiratory organs of man. [5]
CBSE TEST PAPER-02
CLASS - XI BIOLOGY (Body fluids and circulation) [ANSWERS]
Ans 04. The diffusion of chloride ions from blood plasma into RBS’s is known as chloride shift.
a) Occurs from plasma to RBC’s in human body.
b) It maintains ionic balance and electrochemical neutrality.
Ans 05. First step in respiration is called breathing. In breathing atmospheric air is taken in by inspiration and alveolar air is released out by expiration. The exchange of O2 and CO2 between deoxygenated blood and alveoli, transport of gases throughout body by blood, exchange of O2 and CO2 between the oxygenated blood and tissues and utilization of O2 by the cells are the other steps involved in it.
Ans 06. It is “inflammation of the bronchi and is characterized by hypertrophy hyperplasia seromucous glands and goblet cells lining the bronchi”
Symptoms are coughing with thick greenish-yellow sputum. It shows infection, that excessive secretion of mucus. It is caused by pollutants as well as the cigarette smoking. Prevention of Bronchitis –
1) Avoiding exposure to allergens.
2) Treatment involves antibiotic theory & bronchodilator dugs, etc.
Ans.07.
Vital Capacity (VC) Total lung Capacity. (CT2C) 1. Sum total of tidal volume, expiratory reserve
and inspiratory reserve volume.
Sum total of vital capacity and residual volume.
2. VC = Vt + ERV + IRV TLC = VC + RV
3. Value is 3500-4500ml. Value is 5000 – 6000ml 4. Represents maximum amount of air that a
person can expel after filling the lungs to the maximum.
Represents maximum total amount of air which can be present in lungs after maximum inspiratory effort.
Ans 08. The mechanism of breathing in human involves breathing in of air in the lungs and breathing out of air from lungs thoracic cavity. The form is called inspiration and later expiration. The lungs are located in the closed thoracic cavity. A muscular partition called diaphragm separates the thoracic cavity from the abdominal cavity.
During inspiration the diaphragm is lowered due to contraction intercostals muscle.
This result into the increase of volume of thorax causing fall of air pressure in the thoracic cavity lowers the pressure in the lungs and the air rushes from outside into lungs through external nares, trachea & bronchi.
During expiration the diaphragm move upward and the lateral thoracic walls move inwards due to the relaxation of muscles of diaphragm and the intercoastals muscles. This decrease the volume of thorax and the pressure inside the thorax and lungs is increased which results in the expulsion of some of air from the lungs to the atmosphere outside the body.
Ans 09. The following are the main respiratory organs:-
1) Nostrils – These are the paired openings situated at the anterior and posterior ends of the nasal chambers. They are lined up with ciliated epithelium and mucous cells. These prevent the entrance of dust into lungs and help in warming and moistening the air. The nasal chamber opens interiorly by external nostril and posterior internal nostril into the pharynx.
2) Larynx – It is situated at the anterior part of trachea and communicates with the pharynx.
The glottis is protected by a stiff cartilage called epiglottis. The larynx contains pairs of vocal elastic cartilaginou rings to
prevent its collapsing. It is lined internally with mucous membrane to hold the dust particles, bacteria and other foreign bodies. It also warms the air.
4) Bronchi – Inside the thorax, the trachea bifurcates into two branchy and each of which enters into one lung. In each lung, the bronchus again redivides into numerous small branches known as bronchioles. These bronchioles further divide at its ends to form respiratory bronchioles.
5) Lungs – There are two large bag-like spongy structures which are the main respiratory organs. These are enclosed by double pleural membranes. The lungs are divided externally by lobes. The right lung consists of four lobes and left by two lobes. Inside the lungs, the respiratory bronchioles give rise to alveolar ducts, alveolar sac and finally alveoli. Each lung contains millions of alveoli. Each alveolus is exceptionally thin walled. Its walls are highly permeable and richly supplied with blood capillaries.
The blood is supplied to the lungs by a pair of pulmonary arteries. These bring blood which poor in oxygen & rich in CO2. The exchange of gases occurs in the alveoli of the lungs. The oxygenated blood from alveolar capillaries is called by pair of pulmonary vein to be conveyed to the heart.
CBSE TEST PAPER-03
CLASS - XI BIOLOGY (Breathing and Exchange of Gases)
1. Name the place where actual exchange of gases takes place in insects. [1]
2. What is the percentage of O2 in inspired & expired air? [1]
3. What is the utility of chloride shift? [1]
4. What is the difference between carbaminohaemoglobin and oxyhaemoglobin. [2]
5. What is functional residual capacity? [2]
6. Describe the transport of O2 and CO2? [2]
7. Define oxygen dissociation curve? Why it has sigmoidal pattern? [3]
8. What is the role of carbonic anhydrase? Show by series of reactions how carbonic anhydrase starts the reactions leading to the formation of hemoglobinic acid?
[3]
9. Explain how our heart muscles get a continuous supply of atmospheric oxygen.
[5]
CBSE TEST PAPER-03
CLASS - XI BIOLOGY (Body fluids and circulation) [ANSWERS]
Ans 01. Tracheoles.
Ans 02. Inspired air has 21% O2 and expired air has 16% O2.
Ans 03. It maintains the ionic balance and electrochemical neutrality.
Ans 04.
Its formation occurs in the tissues.
Ans 05. When a person inhales and exhales in a normal way, the volume air that remains in the lungs is known as functional residual capacity (FRC). It includes the residual volume and expiratory reserve volume, i. e, FRC = RV + ERV.
Ans 06. O2 is transported as oxyhaemoglobin. In the alveoli of lungs (PO2 is higher), O2 gets bound to hemoglobin that dissociates at tissues where PO2 and H+ concentration are high. Approx 70% CO2 transported as bicarbonate (HCO3-) with the help of the enzyme carbonic anhydrase, 20-25% CO2 is carried by haemoglobin as carbaminohamoglobin. In tissues PCO2 is high its gets bound to blood but in alveoli where PCO2 is low and PO2 is high, this removed from blood.
Ans 07. The relationship between O2 tension and its absorption by haemoglobin produces a graph called oxygen dissociation curve (O2 equilibrium curve). At about 100 mm Hg O2 tension Hb is 98% saturated (complete formation of haemoglobin).
As it falls, the saturation of Hb decreases slowly. When O2 tension is about 40mm Hg, oxyhaemoglobin dissociates and O2
is available to the tissues.
The O2 gets bound to Hb in lung surface and it gets dissociated at tissues.
1 0 20 3 0 4 0 50 6 0 70 8 0
O xygen pressure in m ercury
% saturationwitaO 2
Ans 08. Carbonic Anhydrate : CO2 reacts with water in presence of carbonic anhydrase in erythrocytes, Carbonic acid (H2CO3) is dissociated into hydrogen (H+) and bicarbonate (HCO3
-) ions-). Oxyhaemoglobin (HbO2) of RBC’s is weakly acidic and remain in association with K+ ions as KHbO2. H+ ions combine with haemoglobin.
Bricarbonate ions diffuse out into plasma and combine with haemoglobin to from haemoglobinic acid (H. Hb)
Ans 09. When inspiration occurs, the O2 is taken into lungs. O2 mixes with air already present in alveoli and becomes alveolar air, whose PO2 is 100 m Hg.
As PO2 of blood in the vessels is 40 mmHg oxygen differs into blood vessels from alveoli and the oxyhaemoglobin is formed when oxygen combines loosely with the Fe++ ions of haemoglobin.
Oxygenated blood from the lungs reaches the left auricle through pulmonary vein; to left ventricle is pumped at through aorta also.
The branch supplying blood to heart muscles is coronary artery. In heart muscles, as the PO2 is lower than that of the blood in the branches of coronary artery, oxyhaemoglobin dissociates and releases O2 to cardiac muscles.
CBSE TEST PAPER-01
CLASS - XI BIOLOGY (Body fluids and circulation)
1. Which of the four chambers of the human heart has the thickest muscular wall?
[1]
2. Where are RBCs formed from in an adult human? [1]
3. What is ECG technique? [1]
4. Distinguish between mitral and tricuspid value? [2]
5. Why does the fish heart pump only deoxygenated blood? [2]
6. How is heart failure different from heart attack? [2]
7. What is cardiac cycle? [3]
8. Differentiate between right ventricle and left ventricle. [3]
9. Describe the structure of human heart. [5]
CBSE TEST PAPER-1
CLASS - XI BIOLOGY (Body fluids and circulation) [ANSWERS]
Ans 01. Left ventricle.
Ans 02. RBCS are formed from the bone marrow.
Ans 03. It is a technique to record and photograph the various electric cal changes in the working of the heart.
Ans 04.
Mitral Value Tricuspid value
1. It is called bicuspid value It lies in the region of right atrioventricular aperture.
2. All the two flaps are of almost equal size.
All the three flaps are different in size.
3. There are two flaps in this flap. There are three flaps in this flap.
4. Check back flow of oxygenated blood into left auricle.
Check back flow of the deoxygenated blood into right auricle.
Ans 05. 1) Atrium receives deoxygenated blood from all parts of the body.
2) It is pumped into the ventricle from where it is pumped to the gills.
3) The oxygenated blood flows from the gills to various parts.
Ans 06.
Heart failure Heart attack
1. It refers to the state of the heart when the heart is not pumping blood sufficient to meet the need of the body.
It refers to the state where the respectively. One complete cardiac cycle occurs in 0.8 sec. Three stages of cardiac cycle are-
1) arterial systole 2) ventricular systole 3) Joint diastole.
Ans 08.
Right ventricle Heft ventricle
1. Right ventricle is smaller than the left ventricle.
Left ventricle is comparatively larger than right ventricle.
2. Moderator band present in it. Moderator band is lacking in it.
3. Columnae carneae thicker but less intricate.
Columnae carneae narrower but more intricate.
4. Receives and pushes
deoxygenated blood.
Receives and pumps oxygenated blood.
5. Crescent shaped. Biconvex in shape.
6. The wall of right ventricle is thinner than left ventricle.
The wall of it is thicker than right ventricle.
Ans 09. The heart is a muscular organ situated in thoracic cavity which lies above the diaphragm between the two lungs. It is situated almost in the middle of the chest tilted at its apex to the left. It is enclosed in a double walled membranous sac, the pericardium fitted with pericardial fluid. The heart continuous working without stopping throughout the life of an individual. The heart of an average person at rest under normal circumstances beats. 70 to 80 times in a minute when it contracts its forces and pumps the blood into arteries which supply the blood to body organs. In man and other mammals heart is four chambered structure divisible into two halves right and left.
The right & left halves of the heart are completely separated by septa. Each half has an upper chamber called the auricle and the lower chamber called the ventricle. Each auricle opens into the ventricle of its one side through an auricuo–ventricular aperature. The two apertures are guarded by valves which open only into the ventricle and prevent the back flow of the blood. The mitral valve or bicuspid valve having two flaps is present at the AV opening on the left side and the tricuspid valve
(with three flaps) on the right side of the heart.
The left ventricle is provided with tendinous cords called chordae tendinae and papillary muscle which prevent the valves from being pushed into auricles when the ventricles contract. The starting point of the aorta at left ventricle there is another set of semilunar valves.
CBSE TEST PAPER-02
CLASS - XI BIOLOGY (Body fluids and circulation)
1. In which mammal, the RBC are nucleated? [1]
2. Name any two substances which prevent blood coagulation in uninjured blood vessels.
[1]
3. Name the type of granulocytes that play an important role in detoxification? [1]
4. Name the different types of granulocytes. Give the function of the one which constitutes maximum percentage of total leucocytes.
[2]
5. Why is closed circulatory system considered advantageous? [2]
6. What it is the name of the straw coloured fluid left after clotting of blood? How is it different from blood?
[2]
7. Write a note on “Regulation of cardiac activity”? [3]
8. Why does lymph contain much less proteins than the blood plasma? Name the two principal lymph vessels in humans.
[3]
9. What is lymphatic system? Discuss its importance. [5]
CBSE TEST PAPER-02
CLASS - XI BIOLOGY (Body fluids and circulation) [ANSWERS]
Ans 01. Camel.
Ans 02. Heparin, Antithrombin.
Ans 03. Eosinophils.
Ans 04. Different types of granulocytes are:
(i) Neutrophils – 62%
(ii) Acidophils (eosinophils) – 3%
(iii) Basophils - 0.5% to 1%
Neutrophils are phagocytic i.e, responsible for protection against infection.
Ans 05. Closed circulatory system is considered advantageous for the following reasons- a) It maintains sufficient high blood pressure, blood flows at a high
velocity; this quickens the supply of needed material and removal of wastes from the tissues.
b) The volume of blood flowing to a particular organ / tissues can be regulated to the need of the tissues.
Ans 06. It is called serum
Plasma without coagulation factors is called serum.
It differs from plasma in having much less quantity of proteins; it is outside the blood vessels.
Ans 07. (i) The special neural centre located in medulla oblongata of brain can moderate cardiac function through autonomic nervous systems.
Therefore help in controlling heart regulation.
(ii) The parasympathetic neural signals, (component of ANS) decrease rate of heart beat, speed of conduction of action potential and also the cardiac output.
(iii) The adrenal medullary hormones enhance cardiac output (C.O).
(iv) The neural signals through sympathetic nerves may increase heart beat rate and the strength of ventricular contraction and also cardiac output.
Ans 08. Lymph contains mush less protein than plasma, because the capillary wall is impermeable to larger molecules like proteins.
The two principle lymph vessels are – Right lymphatic duct and thoracic duct.
Ans 09. Lymph is a colourlese tissue fluid resembling the blood except that it has no haemoglobin and RBCs. In comparison to blood, lymph contains less blood proteins, more of waste matter, increased amount of food material and a large number of WBC’s
The tissue fluid is filtered from the blood plasma through the walls of capillaries some WBC also come out from there capillaries Now this tissue fluid enters into lymphatic capillaries as is known as lymph so the tissue fluid is converted into lymph.
Circulation of lymph:
Lymph vessels : Almost all of the body organs have a large number of lymph vessels and lymph capillaries. The walls of lymph vessels have valves (like veins).
They form the network in the organs – one is superficial and other is deep seated. The flow of lymph in these vessels is only one side i.e., from the organs but never to the organs. In human body the following two large lymph vessels are present.
Ductus Thoracious – It start from the abdominal cavity with a dilation called receptaculum chyli. Then it passes into the thoracic cavity then to the left of the neck region. It receives the lymph from the following organs – lower extremities, region of the true pelvis, abdominal region, left upper extremities the left half of the thorax, head, face & neck.
Lymph nodes – These are small globular masses of lymphatic tissue and these arranged in groups from each region organs of the body the lymph flows into definite lymph nodes. The nodes are called regional nodes.
Function of lymph:
Function of lymph: