Consider these statements about systemic and pulmonary circulations:
(i) Deoxygenated blood pumped from the right ventricle is carried by the pulmonary artery to the lungs. (ii) Oxygenated blood is returned to the left atrium from the lungs by the pulmonary veins. (iii) Systemic circulation starts by pumping oxygenated blood from the left ventricle into the aorta. (iv) In the systemic capillaries, oxygenated blood gets mixed with deoxygenated blood to nourish tissues.
Explanation: Statement (iv) is incorrect because there is no mixing of oxygenated and deoxygenated blood in mammals. Oxygenated blood supplies tissues and returns as deoxygenated blood through the veins. Statements (i), (ii), and (iii) are correct.
Question 72 of 100
📘 CLASS XI
Read these statements regarding the portal vascular connections:
(i) A unique vascular connection exists between the digestive tract and liver, called the hepatic portal system. (ii) The hepatic portal vein carries blood from the liver directly to the intestine. (iii) Hepatic portal blood must pass through the liver before reaching the systemic circulation. (iv) The coronary system consists of blood vessels exclusively serving the cardiac musculature.
Explanation: Statement (ii) is incorrect because the hepatic portal vein carries blood from the intestine to the liver. Statements (i), (iii), and (iv) are correct.
Question 73 of 100
📘 CLASS XI
Examine these statements about the neural regulation of cardiac activity:
(i) The primary neural regulatory center for cardiac activity is located in the cerebellum. (ii) Sympathetic neural signals increase the heart rate and strength of ventricular contraction. (iii) Parasympathetic neural signals decrease the rate of heartbeat and speed of action potential conduction. (iv) Adrenal medullary hormones decrease cardiac output during stress.
Explanation: Statement (i) is incorrect because the cardiac regulatory centre is located in the medulla oblongata. Statement (iv) is incorrect because adrenal medullary hormones increase cardiac output. Statements (ii) and (iii) are correct.
Question 74 of 100
📘 CLASS XI
Read these statements regarding hypertension (high blood pressure):
(i) Normal blood pressure is defined as a reading of 120/80 mm Hg. (ii) In 120/80 mm Hg, 120 represents diastolic pressure and 80 represents systolic pressure. (iii) Persistent blood pressure readings of 140/90 mm Hg or higher indicate hypertension. (iv) Chronic hypertension can lead to damage in vital organs such as the brain and kidney.
Explanation: Statement (ii) is incorrect because 120 mm Hg is the systolic pressure and 80 mm Hg is the diastolic pressure. Statements (i), (iii), and (iv) are correct.
Question 75 of 100
📘 CLASS XI
Analyze these statements regarding Coronary Artery Disease (CAD) and other cardiac conditions:
(i) Coronary Artery Disease is commonly referred to as atherosclerosis. (ii) CAD is caused by deposits of calcium, fat, cholesterol, and fibrous tissues in the coronary arteries. (iii) Deposits of calcium and fats make the lumen of coronary arteries wider. (iv) Angina pectoris refers to acute chest pain caused by insufficient oxygen reaching the heart muscle.
Explanation: Statement (iii) is incorrect because atherosclerotic deposits narrow the lumen of coronary arteries, reducing blood flow. Statements (i), (ii), and (iv) are correct.
Question 76 of 100
📘 CLASS XI
Consider the following statements comparing human blood plasma and lymph:
(i) Both plasma and lymph are viscous, straw-coloured fluids of identical cellular and protein composition. (ii) Lymph is a colourless fluid that contains specialised lymphocytes but lacks larger proteins and most formed elements. (iii) Plasma contains 90–92 per cent water and 6–8 per cent proteins, along with minerals and inactive clotting factors. (iv) Both blood plasma and lymph contain clotting factors in their active state at all times.
Explanation: Statements (ii) and (iii) are correct. Statement (i) is incorrect because lymph lacks the larger proteins and most formed elements found in plasma. Statement (iv) is incorrect because clotting factors remain in an inactive form to prevent spontaneous clotting within blood vessels.
Question 77 of 100
📘 CLASS XI
Examine these statements about electrocardiogram (ECG) waves and their clinical interpretation:
(i) The electrical excitation of the atria is depicted by the P-wave, which leads to atrial contraction. (ii) The QRS complex represents the repolarization of the ventricles, triggering ventricular contraction. (iii) The T-wave represents the return of the ventricles from an excited to a normal state (repolarisation). (iv) Any prominent deviation from the standard ECG shape in a given lead configuration indicates a potential cardiac abnormality.
Explanation: Statements (i), (iii), and (iv) are correct. Statement (ii) is incorrect because the QRS complex represents ventricular depolarization, not repolarization.
Question 78 of 100
📘 CLASS XI
Study these statements regarding Open and Closed Circulatory Systems:
(i) In open circulatory systems, blood is pumped by the heart into large vessels that empty into body cavities called sinuses. (ii) Arthropods and molluscs possess a closed circulatory system. (iii) Annelids and chordates have a closed circulatory system where blood is pumped through a closed network of vessels. (iv) A closed circulatory system is more advantageous because the flow of fluid can be more precisely regulated.
Explanation: Statements (i), (iii), and (iv) are correct. Statement (ii) is incorrect because arthropods and most molluscs possess an open circulatory system.
Question 79 of 100
📘 CLASS XI
Read the following statements regarding thrombocytes (platelets):
(i) Thrombocytes are cell fragments produced from specialized cells called megakaryocytes in the bone marrow. (ii) The normal count of platelets in a healthy human is 1,500 to 3,500 per cubic millimeter of blood. (iii) Platelets release a variety of substances, most of which are involved in blood coagulation. (iv) A significant reduction in platelet count leads to clotting disorders and excessive blood loss.
Explanation: Statements (i), (iii), and (iv) are correct. Statement (ii) is incorrect because the normal platelet count is approximately 1,50,000 to 3,50,000 per mm³ of blood.
Question 80 of 100
📘 CLASS XI
Analyze the following statements about Double Circulation pathways:
(i) The pathway of deoxygenated blood from the right ventricle, through the pulmonary artery and lungs, returning as oxygenated blood to the left atrium via pulmonary veins, is the pulmonary circulation. (ii) Systemic circulation starts at the left ventricle, pumps oxygenated blood into the aorta to reach all tissues, and returns deoxygenated blood via the vena cava to the right atrium. (iii) Deoxygenated blood pumped by the left ventricle is oxygenated in the lungs. (iv) Systemic circulation provides nutrients, oxygen, and other essential substances to tissues and removes carbon dioxide and wastes.
Explanation: Statements (i), (ii), and (iv) are correct. Statement (iii) is incorrect because the right ventricle pumps deoxygenated blood to the lungs, whereas the left ventricle pumps oxygenated blood to the body.
