Analyze these statements about Erythrocyte (RBC) characteristics and lifespan:
(i) A healthy individual contains 12–16 gms of hemoglobin in every 10 mL of blood. (ii) The red color of RBCs is due to an iron-containing complex protein called hemoglobin. (iii) RBCs have an average life span of 120 days. (iv) The graveyard of RBCs, where they are destroyed after their lifespan, is the spleen.
Explanation: Statements (ii), (iii), and (iv) are correct. Statement (i) is incorrect because a healthy individual has 12–16 g of hemoglobin in every 100 mL of blood, not 10 mL.
Question 92 of 100
📘 CLASS XI
Examine the relative abundance percentages of different types of human Leucocytes (WBCs):
(i) Neutrophils are the most abundant leucocytes, making up 60–65 per cent of the total WBCs. (ii) Basophils are the least abundant, constituting 0.5–1 per cent of the total WBCs. (iii) Lymphocytes account for 20–25 per cent of the total leucocytes. (iv) Monocytes make up 10–12 per cent of the total WBCs and are highly phagocytic in nature.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because monocytes constitute 6–8 per cent of the total WBCs, not 10–12 per cent.
Question 93 of 100
📘 CLASS XI
Read the statements regarding the transition from Joint Diastole to Atrial Systole:
(i) In joint diastole, all four heart chambers are in a relaxed state with the semilunar valves closed. (ii) Tricuspid and bicuspid valves are open during joint diastole, allowing passive blood flow into the ventricles. (iii) The action potential from the SAN causes the atria to undergo atrial systole, which increases ventricular blood flow by about 30%. (iv) During atrial systole, ventricular pressure rises and immediately forces the closure of the tricuspid and bicuspid valves.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because closure of the tricuspid and bicuspid valves occurs during ventricular systole, not atrial systole.
Question 94 of 100
📘 CLASS XI
Examine these statements regarding standard ECG connection leads and chest leads:
(i) For a standard ECG, three electrical leads are used, connected to each wrist and the left ankle. (ii) These electrical leads continuously monitor heart activity during a cardiac cycle. (iii) For a detailed evaluation of heart function, multiple leads are attached to the chest region. (iv) The right ankle is always connected to the standard active lead during a routine ECG setup.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because the standard ECG uses leads attached to each wrist and the left ankle, not the right ankle.
Question 95 of 100
📘 CLASS XI
Consider these statements about the histology of human Blood Vessel walls:
(i) Both arteries and veins possess three distinct tissue layers: tunica intima, tunica media, and tunica externa. (ii) Tunica intima consists of an inner lining of squamous endothelium. (iii) Tunica media consists of smooth muscle and elastic fibres and is comparatively thinner in arteries than in veins. (iv) Tunica externa is an external layer of fibrous connective tissue with collagen fibres.
Explanation: Statements (i), (ii), and (iv) are correct. Statement (iii) is incorrect because the tunica media is thicker in arteries and comparatively thinner in veins.
Question 96 of 100
📘 CLASS XI
Study the evolutionary vertebrate heart types and deoxygenated/oxygenated blood pathways:
(i) In fishes, the heart pumps deoxygenated blood to the gills, where it is oxygenated and supplied directly to body parts. (ii) In amphibians, the left atrium receives oxygenated blood from the gills/lungs/skin, while the right atrium receives deoxygenated blood. (iii) In reptiles, there is no mixing of blood in the ventricles because they have completely divided ventricular chambers. (iv) Birds and mammals have two separate circulatory pathways (complete double circulation).
Explanation: Statements (i), (ii), and (iv) are correct. Statement (iii) is incorrect because reptiles (except crocodiles) possess a three-chambered heart with incomplete double circulation, where oxygenated and deoxygenated blood mix in the single ventricle.
Question 97 of 100
📘 CLASS XI
Read these statements regarding ECG waves and their associated electrical phenomena:
(i) The P-wave corresponds to the electrical depolarization (excitation) of the atria. (ii) The QRS complex represents the depolarization of the ventricles, initiating ventricular contraction. (iii) The T-wave represents the repolarization (return to normal) of the ventricles. (iv) The beginning of the P-wave marks the start of ventricular systole.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because ventricular systole begins shortly after the Q-wave of the QRS complex, not the P-wave, which represents atrial depolarization.
Question 98 of 100
📘 CLASS XI
Read the statements below regarding Lymph structure and transport functions:
(i) Lymph is almost identical to blood plasma except that it contains larger proteins and fewer lymphocytes. (ii) Lymph is a colourless fluid that serves as an important carrier for nutrients and hormones. (iii) Fats are absorbed through the lymph in lacteals situated in the intestinal villi. (iv) The lymphatic system collects tissue fluid (interstitial fluid) and drains it back into the major veins.
Explanation: Statements (ii), (iii), and (iv) are correct. Statement (i) is incorrect because lymph lacks larger plasma proteins and contains specialized lymphocytes.
Question 99 of 100
📘 CLASS XI
Analyze these statements regarding the clinical definition of various circulatory system conditions:
(i) Hypertension is diagnosed when repeated blood pressure checks show a reading of 140/90 mm Hg or higher. (ii) Heart failure is the state of the heart when it is not pumping blood effectively enough to meet the body's needs. (iii) Cardiac arrest occurs when the heart muscle is suddenly damaged by an inadequate blood supply. (iv) A heart attack refers to the clinical event when the heart stops beating completely.
Explanation: Statements (i) and (ii) are correct. Statements (iii) and (iv) are incorrect because their definitions are interchanged. Cardiac arrest is when the heart stops beating completely, whereas a heart attack is caused by inadequate blood supply to the heart muscle.
Question 100 of 100
📘 CLASS XI
Read these statements regarding the regulation of heart rate and cardiac output:
(i) The primary pacemaker of the human heart is the sino-atrial node, making heart activities myogenic. (ii) Sympathetic stimulation decreases the heart rate but increases the strength of ventricular contraction. (iii) Parasympathetic stimulation decreases the heart rate, the speed of action potential conduction, and overall cardiac output. (iv) Adrenal medullary hormones can increase overall cardiac output during stress.
Explanation: Statements (i), (iii), and (iv) are correct. Statement (ii) is incorrect because sympathetic stimulation increases both the heart rate and the strength of ventricular contraction, thereby increasing cardiac output.
