Zoology MCQs for NEET — Practice Questions with Answers

A thrombus is a blood clot that forms in the circulatory system. It can obstruct blood flow, leading to various medical conditions. The other options do not correctly describe this condition.

The Sinoatrial Node (SAN) initiates the heartbeat, which is true. However, the sympathetic nerve fibers increase cardiac activity, but this does not explain why the SAN initiates the heartbeat. Therefore, both A and R are true, but R is not a correct explanation of A.

Clotting of blood is indeed a characteristic of human blood, making A true. Each erythrocyte possesses hemoglobin (Hb), which is also true. However, the presence of Hb in erythrocytes does not explain why blood clots. Therefore, both A and R are true, but R is not a correct explanation of A.

Pulmonary respiration refers to the process of breathing involving the lungs. Among the options given, humans show pulmonary respiration. In humans, the respiratory system includes the lungs where oxygen is taken in and carbon dioxide is expelled.

The trachea is supported by cartilaginous rings that are C-shaped. These C-shaped rings provide structural support to the trachea, preventing it from collapsing while allowing flexibility and movement during breathing and swallowing.

The lung contains many small balloon-like air sacs called alveoli. These alveoli are the sites of gas exchange in the respiratory system. They provide a large surface area for oxygen and carbon dioxide to be exchanged efficiently between the lungs and the bloodstream.

The intake of air is called inhalation. During inhalation, the diaphragm and intercostal muscles contract, causing the chest cavity to expand and air to be drawn into the lungs.

Intercostal muscles regulate the movement of the ribs. These muscles are located between the ribs and play a crucial role in the mechanics of breathing by helping expand and contract the chest cavity during inhalation and exhalation.

The muscles present between the ribs are called intercostal muscles. These muscles are crucial for the mechanics of breathing as they help expand and contract the rib cage, allowing the lungs to fill and empty air efficiently.

The respiratory control centers are located in the medulla oblongata. This part of the brainstem plays a key role in regulating the rate and depth of breathing by sending signals to the respiratory muscles, ensuring that the body maintains proper levels of oxygen and carbon dioxide in the blood.