Life Process (Class - X)

The heart is composed of cardiac muscle, which is a specialized type of muscle tissue found only in the heart. Cardiac muscle is striated (has bands) like skeletal muscle but involuntary like smooth (unstriated) muscle. The heart is NOT made of unstriated muscle (smooth muscle is found in organs like stomach and intestines), and sinuses are air-filled cavities, not muscle tissue.

The upper two chambers of the heart are called atria (singular: atrium). The right atrium receives deoxygenated blood from the body, and the left atrium receives oxygenated blood from the lungs. Ventricles are the LOWER chambers, and 'Coronus' is not an anatomical term related to the heart.

The lower two chambers of the heart are called ventricles. The right ventricle pumps blood to the lungs, and the left ventricle pumps oxygenated blood to the rest of the body. Atria are the UPPER chambers, and sinuses are not related to heart chambers but are air-filled spaces in the skull.

Arteries are blood vessels that carry blood away from the heart to the body's tissues. They have thick, muscular walls to withstand the high pressure generated by the heart's pumping action. Veins carry blood back to the heart, not away from it.

Veins are blood vessels that return blood from the body's tissues back to the heart. They have thinner walls than arteries and contain valves to prevent backflow. Capillaries are tiny vessels where exchange of materials occurs, not the main transport vessels back to heart.

The septum is the thick muscular wall that separates the left and right sides of the heart. This separation ensures that oxygenated and deoxygenated blood do not mix. The pericardium is the protective sac around the heart, not an internal partition.

Oxygenated blood has picked up oxygen from the lungs and carries it to body tissues. It is bright red and contains relatively more oxygen than deoxygenated blood, which has delivered its oxygen to tissues and is returning to the lungs.

Animals with four-chambered hearts have double circulation: pulmonary circulation (heart to lungs and back) and systemic circulation (heart to body and back). This prevents mixing of oxygenated and deoxygenated blood. Single circulation occurs in fish with two-chambered hearts.

A heartbeat is one complete cycle of cardiac contraction (systole) and relaxation (diastole). Dialysis is blood filtration, blood pressure is the force of blood against vessel walls - neither describes the cardiac cycle.

Fish have two-chambered hearts (one atrium, one ventricle) and single circulation. Blood passes through the heart once in a complete circuit: heart → gills → body → back to heart. This is less efficient than double circulation but adequate for their aquatic lifestyle.

Deoxygenated blood has delivered its oxygen to body tissues and is returning to the lungs. It contains relatively less oxygen than oxygenated blood. There is no such term as 'anoxygenic blood' in physiology - this is a distractor.

A normal resting heart rate for a healthy young adult is 60-100 beats per minute, with 72 bpm being a commonly cited average. The range of 70-72 bpm falls within normal limits. Options A and B are also within normal range, but C is most precise.

A sphygmomanometer is the medical instrument used to measure blood pressure. It consists of an inflatable cuff and a pressure gauge. Barometer measures atmospheric pressure, hydrometer measures liquid density - neither is used for blood pressure.

Diastolic pressure is the minimum pressure in arteries when the heart is in relaxation phase (diastole). Systolic pressure is the maximum pressure during contraction. The relaxation phase allows chambers to fill with blood before the next contraction.

Systolic pressure is the maximum pressure in arteries during ventricular contraction (systole). This is when blood is forcefully ejected from the heart into the aorta. Diastolic pressure is the minimum during relaxation, not the maximum.

120/80 mm Hg is the universally accepted standard normal blood pressure reading for healthy adults. 110/75 is on the low side while 145/90 falls in the hypertensive range, making them incorrect as 'normal' values.

Excretion is the biological process responsible for removing nitrogenous waste products like urea, uric acid, and ammonia from organisms. Respiration deals with gas exchange, while circulation is about transporting substances throughout the body.

Plants excrete waste materials in solid or semi-solid forms like gums, resins, latex, and rubber. These substances are byproducts of plant metabolism that are stored in specialized cells or ducts. Oxygen and carbon dioxide are involved in gas exchange, not excretory waste secretion in this context.

Dialysis is the medical procedure that artificially cleans blood by removing waste products like urea, creatinine, and excess salts when kidneys fail. It works on the principle of diffusion through a semi-permeable membrane. Hydrolysis is a chemical breakdown process, while excretion is the general biological process.

Kidneys are the primary organs of the excretory system, filtering blood and producing urine to remove metabolic wastes. They are not part of the nutrition system (digestion/absorption), transportation system (circulatory), or respiratory system (gas exchange).

Systemic circulation refers to the movement of blood from the heart to the entire body (excluding lungs) and back to the heart. Pulmonary circulation specifically involves circulation between heart and lungs. Since the question mentions 'rest of body' (not lungs), the correct answer is systemic circulation only.

Amphibians (like frogs) and reptiles (like lizards) have three-chambered hearts with two atria and one ventricle, which allows some mixing of oxygenated and deoxygenated blood. Fish have two-chambered hearts, while birds and mammals have four-chambered hearts.

Humans have two ureters - one connecting each kidney to the urinary bladder. They transport urine from the kidneys to the bladder for storage before urination. This bilateral arrangement matches the paired nature of kidneys.

Pulmonary circulation specifically refers to the blood flow pathway from the heart to the lungs for oxygenation and back to the heart. Systemic circulation is the circuit to the rest of the body. The question specifically mentions 'lungs' as the destination.

Nephrons are the microscopic functional units of the kidney, each consisting of a glomerulus and tubule system that filters blood and produces urine. A human kidney contains approximately 1 million nephrons. Bladders store urine, while urethra is the exit tube.