Zoology MCQs for NEET — Practice Questions with Answers

The mammalian heart is myogenic, meaning it generates its own electrical impulses without requiring external nerve input. This property allows the heart to maintain a consistent and rhythmic heartbeat.

Thrombocytes, also known as platelets, are responsible for blood clotting. A reduction in the number of thrombocytes can lead to clotting disorders, causing excessive loss of blood from the body. Hence, the correct answer is 'Thrombocytes'.

In humans, erythrocytes (red blood cells) are anucleate, meaning they do not contain a nucleus. This is in contrast to frogs, whose erythrocytes do contain a nucleus. The lack of a nucleus in human erythrocytes provides more space for haemoglobin, enabling more efficient oxygen transportation.

The average volume of blood in an adult human is approximately 5 liters. This volume can vary slightly depending on factors such as body size and health conditions, but 5 liters is a widely accepted average.

The instrument used for measuring blood pressure is called a sphygmomanometer. This device typically consists of an inflatable cuff to restrict blood flow and a mercury or aneroid manometer to measure the pressure.

A heart murmur is typically caused by a defective or leaky valve in the heart. This can lead to abnormal sounds during the heartbeat cycle due to turbulent blood flow. Coronary thrombosis, arterial pulse, and underdeveloped atrium are not directly related to heart murmurs.

The thin membrane surrounding the heart is called the pericardium. It is a double-walled sac that contains the heart and the roots of the great vessels. The myocardium is the muscular tissue of the heart, the pleural membrane surrounds the lungs, and the parietal peritoneum lines the abdominal cavity.

The three important proteins present in blood are Albumin, Globulin, and Fibrinogen. Albumin helps to maintain the osmotic pressure of blood, Globulins are involved in immune responses, and Fibrinogen is crucial for blood clotting.

The QRS complex in an ECG represents the depolarization of the ventricles, which leads to ventricular contraction or systole. This is a crucial part of the cardiac cycle where blood is pumped out of the ventricles to the lungs and the rest of the body.

The heart is mesodermal in origin. During embryonic development, the mesoderm layer gives rise to the cardiovascular system, including the heart, blood vessels, and blood cells. This is a fundamental concept in developmental biology.