Zoology MCQs for NEET — Practice Questions with Answers

ECG (Electrocardiogram) is an important method for checking the health-related problems of the heart. It records the electrical activity of the heart over a period of time and helps in diagnosing various heart conditions such as arrhythmias, heart attacks, and other cardiac disorders.

Leucopenia is a condition characterized by a decrease in the number of leukocytes (white blood cells) below 5000 per cubic mm of blood. This can make an individual more susceptible to infections and can be caused by various factors including bone marrow disorders, autoimmune diseases, and certain medications.

Carbonic anhydrase is an enzyme present in red blood cells (RBC). It catalyzes the conversion of carbon dioxide and water to carbonic acid, which then dissociates into bicarbonate and hydrogen ions. This reaction is crucial for the transport of carbon dioxide from tissues to the lungs.

The heart beat is auto-inducing, which means it is initiated by the heart itself without any external stimulation. This is due to the presence of pacemaker cells in the sinoatrial (SA) node that generate electrical impulses autonomously.

Blood plasma is slightly basic with a pH range of about 7.35 to 7.45. This basic nature helps in maintaining the body's pH balance and proper functioning of metabolic processes.

A clot of blood contains fibrin. During the clotting process, fibrinogen is converted into fibrin by the action of thrombin. Fibrin forms a mesh-like structure that traps blood cells, leading to the formation of a stable blood clot.

An increase in the number of leucocytes (white blood cells) beyond normal usually indicates an infection. The body's immune system produces more white blood cells to fight off the infection, which is why their number increases.

Blood is red due to the presence of hemoglobin in red blood cells (RBCs). However, earthworms have a different system. They do not have RBCs; instead, their blood contains a pigment called hemoglobin which is dissolved in the plasma. This makes their blood red despite the absence of RBCs.

The pacemaker of the heart is the sinoatrial (SA) node. It is responsible for generating the electrical impulses that initiate the heartbeat, thereby setting the pace for the heart's rhythm.

Prothrombin is a protein produced in the liver. It plays a critical role in blood clotting by converting to thrombin in the clotting process. This is essential for stopping bleeding and repairing damaged blood vessels.