Consider the following statements regarding the components of human blood plasma:
(i) Water constitutes about 90–92 per cent of plasma, and proteins contribute 6–8 per cent of it. (ii) Globulins are the most abundant plasma proteins and are primarily involved in maintaining osmotic balance. (iii) Fibrinogen is essential for the coagulation or clotting of blood. (iv) Plasma contains small amounts of minerals such as Na+, Ca2+, Mg2+, HCO3-, and Cl-.
Explanation: Statement (ii) is incorrect because albumins, not globulins, are the major plasma proteins responsible for maintaining osmotic balance. Globulins mainly participate in body defence. Statements (i), (iii), and (iv) are correct.
Question 2 of 100
📘 CLASS XI
Examine these statements regarding the structural features of human erythrocytes (RBCs):
(i) They are formed in the yellow bone marrow in adults. (ii) They are devoid of a nucleus in most mammals and have a biconcave shape. (iii) A healthy adult man averages 5 to 5.5 million RBCs per mm3 of blood. (iv) RBCs have an average life span of 120 days, after which they are destroyed in the liver, known as the graveyard of RBCs.
Explanation: Statement (i) is incorrect because RBCs are formed in the red bone marrow. Statement (iv) is incorrect because the spleen is known as the graveyard of RBCs. Statements (ii) and (iii) are correct.
Question 3 of 100
📘 CLASS XI
Read the following statements regarding blood groupings in humans:
(i) ABO grouping is based on the presence or absence of two surface antibodies on the RBCs. (ii) The plasma of different individuals contains two natural antigens. (iii) Group O individuals are called universal donors because their RBCs lack both surface antigens A and B. (iv) Persons with blood group AB can accept blood from any donor group and are called universal recipients.
Explanation: Statement (i) is incorrect because ABO grouping is based on antigens present on RBCs. Statement (ii) is incorrect because plasma contains natural antibodies, not antigens. Statements (iii) and (iv) are correct.
Question 4 of 100
📘 CLASS XI
Read these statements regarding the process of blood coagulation:
(i) A reddish-brown scum formed at the site of injury is a clot consisting of a network of fibrins. (ii) Thrombin converts inactive fibrinogen in plasma into active fibrin. (iii) Thrombokinase is an inactive protein present directly in plasma that gets converted to active thrombin. (iv) Calcium ions (Ca2+) play a crucial role in blood clotting.
Explanation: Statement (iii) is incorrect because thrombokinase is an enzyme complex formed during the clotting cascade. Prothrombin, not thrombokinase, is converted into thrombin. Statements (i), (ii), and (iv) are correct.
Question 5 of 100
📘 CLASS XI
Consider the following statements about lymph (tissue fluid):
(i) As blood passes through tissue capillaries, some water and large proteins leak out into intercellular spaces, forming interstitial fluid. (ii) It has the same mineral distribution as that found in blood plasma. (iii) Lymph is a colourless fluid containing specialized lymphocytes responsible for immune responses. (iv) Fats are absorbed through lymph in lacteals present in the intestinal villi.
Explanation: Statement (i) is incorrect because large proteins do not normally leak out of blood capillaries. Statements (ii), (iii), and (iv) are correct.
Question 6 of 100
📘 CLASS XI
Analyze these statements regarding different types of WBCs (Leucocytes):
(i) Neutrophils are the most abundant WBCs (60–65%) while basophils are the least abundant (0.5–1%). (ii) Monocytes (6–8%) and eosinophils are phagocytic cells that destroy foreign organisms. (iii) Basophils secrete histamine, serotonin, and heparin, and are involved in inflammatory reactions. (iv) Lymphocytes (20–25%) are of B and T types, responsible for the immune responses of the body.
Explanation: Statement (ii) is incorrect because neutrophils and monocytes are the principal phagocytic cells. Eosinophils mainly resist parasitic infections and participate in allergic responses. Statements (i), (iii), and (iv) are correct.
Question 7 of 100
📘 CLASS XI
Read the following statements about the human heart chambers and valves:
(i) The wall of the atria is much thicker than the wall of the ventricles. (ii) The bicuspid or mitral valve guards the opening between the left atrium and left ventricle. (iii) The opening between the right atrium and right ventricle is guarded by the tricuspid valve. (iv) Semilunar valves guard the openings of the right and left ventricles into the pulmonary artery and aorta respectively.
Explanation: Statement (i) is incorrect because the walls of the ventricles are much thicker than those of the atria. Statements (ii), (iii), and (iv) correctly describe the valves of the human heart.
Question 8 of 100
📘 CLASS XI
Check the following statements regarding the nodal tissue of the human heart:
(i) The sino-atrial node (SAN) is located in the lower left corner of the right atrium. (ii) The atrio-ventricular node (AVN) is situated in the upper right corner of the right atrium. (iii) The nodal musculature is autoexcitable, meaning it can generate action potentials without external stimuli. (iv) The SAN generates the maximum number of action potentials (70–75 min-1) and is called the pacemaker.
Explanation: Statements (i) and (ii) are incorrect because the SAN is located in the upper right corner of the right atrium, whereas the AVN is situated in the lower left corner near the atrio-ventricular septum. Statements (iii) and (iv) are correct.
Question 9 of 100
📘 CLASS XI
Examine the following statements regarding the cardiac cycle events:
(i) During joint diastole, all four chambers of the heart are in a relaxed state. (ii) Atrial systole, initiated by SAN excitation, increases the flow of blood into the ventricles by about 30 percent. (iii) Ventricular contraction (systole) coincides with atrial systole. (iv) The duration of a single cardiac cycle is 0.8 seconds in a heart beating 72 times per minute.
Explanation: Statement (iii) is incorrect because ventricular systole coincides with atrial diastole. Statements (i), (ii), and (iv) are correct.
Question 10 of 100
📘 CLASS XI
Read these statements regarding ECG (Electrocardiogram) waves:
(i) The P-wave represents the electrical excitation (depolarisation) of the atria. (ii) The QRS complex represents the depolarisation of the ventricles, which initiates ventricular contraction. (iii) The T-wave represents the ventricles returning to the normal (repolarisation) state. (iv) The end of the T-wave marks the beginning of ventricular systole.
Explanation: Statement (iv) is incorrect because the end of the T-wave marks the end of ventricular systole. Statements (i), (ii), and (iii) are correct.
