Chapter 15: Body Fluids and Circulation Assertion-Reason Questions | biology Class 11 CBSE

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 1

Logic Check

Assertion (A): Plasma without clotting factors is called serum. Reason (R): Clotting factors are present in plasma in an inactive form and are consumed during coagulation.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 2

Logic Check

Assertion (A): RBCs are biconcave and lack a nucleus in most mammals. Reason (R): The absence of a nucleus in RBCs maximises space for haemoglobin and increases surface area for gas exchange.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 3

Logic Check

Assertion (A): The spleen is called the graveyard of RBCs. Reason (R): RBCs are produced in the spleen and released into circulation after a lifespan of 120 days.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 4

Logic Check

Assertion (A): Neutrophils are the most abundant leucocytes in human blood. Reason (R): Neutrophils constitute 60–65 per cent of total WBCs and are phagocytic cells that destroy foreign organisms.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 5

Logic Check

Assertion (A): Basophils are the most abundant of all the granulocytes. Reason (R): Basophils secrete histamine, serotonin, and heparin and are involved in inflammatory reactions.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 6

Logic Check

Assertion (A): Persons with AB blood group are called universal recipients. Reason (R): AB blood group individuals have both A and B antigens on RBCs but no antibodies in their plasma.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 7

Logic Check

Assertion (A): Group O individuals are called universal donors. Reason (R): Group O blood has no A or B antigens on RBC surfaces, so it is not attacked by anti-A or anti-B antibodies in any recipient's plasma.

Reasoning Options

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Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 8

Logic Check

Assertion (A): Rh incompatibility during the first pregnancy never causes erythroblastosis foetalis. Reason (R): During the first pregnancy, the placenta separates maternal and foetal blood so the mother is not exposed to foetal Rh antigens until delivery.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 9

Logic Check

Assertion (A): Calcium ions play a very important role in blood clotting. Reason (R): Calcium ions are required as cofactors for the formation of the thrombokinase complex, which converts prothrombin to thrombin in the coagulation cascade.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 10

Logic Check

Assertion (A): Lymph is a red-coloured fluid that contains RBCs and large plasma proteins. Reason (R): Lymph is derived from tissue fluid formed when blood plasma filters through capillary walls, leaving large proteins and formed elements behind.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 11

Logic Check

Assertion (A): Dietary fats are absorbed into the blood through lymph via lacteals in the intestinal villi. Reason (R): Fat particles (chylomicrons) are too large to enter blood capillaries directly and must use the lymphatic route via lacteals.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 12

Logic Check

Assertion (A): The closed circulatory system is more advantageous than the open circulatory system. Reason (R): In a closed circulatory system, blood flows through a closed network of vessels, allowing the flow of fluid to be more precisely regulated.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 13

Logic Check

Assertion (A): Amphibians exhibit complete double circulation. Reason (R): In amphibians, the single ventricle receives both oxygenated and deoxygenated blood, resulting in mixing and delivery of mixed blood to the body.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 14

Logic Check

Assertion (A): The sino-atrial node is called the pacemaker of the heart. Reason (R): The SAN generates the maximum number of action potentials (70–75 per minute) and initiates and maintains the rhythmic contractile activity of the heart.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 15

Logic Check

Assertion (A): The heart is described as myogenic. Reason (R): The cardiac muscle (nodal tissue) can generate action potentials without any external stimuli and is therefore autoexcitable.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 16

Logic Check

Assertion (A): The walls of the ventricles are much thicker than those of the atria. Reason (R): Ventricles must generate greater pressure to pump blood into the pulmonary artery and aorta against resistance, requiring more muscular walls.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): The tricuspid valve is located between the left atrium and the left ventricle. Reason (R): The left atrio-ventricular opening is guarded by a valve with three muscular flaps.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 18

Logic Check

Assertion (A): The semilunar valves close during ventricular diastole. Reason (R): When the ventricles relax, ventricular pressure falls below arterial pressure in the pulmonary artery and aorta, causing the semilunar valves to close and prevent backflow of blood into the ventricles.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 19

Logic Check

Assertion (A): The first heart sound 'lub' is produced by the closure of semilunar valves. Reason (R): The second heart sound 'dub' is associated with the closure of the tricuspid and bicuspid valves.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): Stroke volume multiplied by heart rate gives cardiac output. Reason (R): Cardiac output is defined as the volume of blood pumped out by each ventricle per minute and averages 5 litres in a healthy individual.

Reasoning Options

ByteNotes

Chapter sections

Chapter 15: Body Fluids and Circulation | Assertion-Reason

Assertion (A): Plasma without clotting factors is called serum. Reason (R): Clotting factors are present in plasma in an inactive form and are consumed during coagulation.

Assertion (A): RBCs are biconcave and lack a nucleus in most mammals. Reason (R): The absence of a nucleus in RBCs maximises space for haemoglobin and increases surface area for gas exchange.

Assertion (A): The spleen is called the graveyard of RBCs. Reason (R): RBCs are produced in the spleen and released into circulation after a lifespan of 120 days.

Assertion (A): Neutrophils are the most abundant leucocytes in human blood. Reason (R): Neutrophils constitute 60–65 per cent of total WBCs and are phagocytic cells that destroy foreign organisms.

Assertion (A): Basophils are the most abundant of all the granulocytes. Reason (R): Basophils secrete histamine, serotonin, and heparin and are involved in inflammatory reactions.

Assertion (A): Persons with AB blood group are called universal recipients. Reason (R): AB blood group individuals have both A and B antigens on RBCs but no antibodies in their plasma.

Assertion (A): Group O individuals are called universal donors. Reason (R): Group O blood has no A or B antigens on RBC surfaces, so it is not attacked by anti-A or anti-B antibodies in any recipient's plasma.

Assertion (A): Rh incompatibility during the first pregnancy never causes erythroblastosis foetalis. Reason (R): During the first pregnancy, the placenta separates maternal and foetal blood so the mother is not exposed to foetal Rh antigens until delivery.

Assertion (A): Calcium ions play a very important role in blood clotting. Reason (R): Calcium ions are required as cofactors for the formation of the thrombokinase complex, which converts prothrombin to thrombin in the coagulation cascade.

Assertion (A): Lymph is a red-coloured fluid that contains RBCs and large plasma proteins. Reason (R): Lymph is derived from tissue fluid formed when blood plasma filters through capillary walls, leaving large proteins and formed elements behind.

Assertion (A): Dietary fats are absorbed into the blood through lymph via lacteals in the intestinal villi. Reason (R): Fat particles (chylomicrons) are too large to enter blood capillaries directly and must use the lymphatic route via lacteals.

Assertion (A): The closed circulatory system is more advantageous than the open circulatory system. Reason (R): In a closed circulatory system, blood flows through a closed network of vessels, allowing the flow of fluid to be more precisely regulated.

Assertion (A): Amphibians exhibit complete double circulation. Reason (R): In amphibians, the single ventricle receives both oxygenated and deoxygenated blood, resulting in mixing and delivery of mixed blood to the body.

Assertion (A): The sino-atrial node is called the pacemaker of the heart. Reason (R): The SAN generates the maximum number of action potentials (70–75 per minute) and initiates and maintains the rhythmic contractile activity of the heart.

Assertion (A): The heart is described as myogenic. Reason (R): The cardiac muscle (nodal tissue) can generate action potentials without any external stimuli and is therefore autoexcitable.

Assertion (A): The walls of the ventricles are much thicker than those of the atria. Reason (R): Ventricles must generate greater pressure to pump blood into the pulmonary artery and aorta against resistance, requiring more muscular walls.

Assertion (A): The tricuspid valve is located between the left atrium and the left ventricle. Reason (R): The left atrio-ventricular opening is guarded by a valve with three muscular flaps.

Assertion (A): The semilunar valves close during ventricular diastole. Reason (R): When the ventricles relax, ventricular pressure falls below arterial pressure in the pulmonary artery and aorta, causing the semilunar valves to close and prevent backflow of blood into the ventricles.

Assertion (A): The first heart sound 'lub' is produced by the closure of semilunar valves. Reason (R): The second heart sound 'dub' is associated with the closure of the tricuspid and bicuspid valves.

Assertion (A): Stroke volume multiplied by heart rate gives cardiac output. Reason (R): Cardiac output is defined as the volume of blood pumped out by each ventricle per minute and averages 5 litres in a healthy individual.

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