Respiration-2 - NEET MCQ

The method of respiration in hibernating frogs depends on their metabolic state and the level of oxygen availability in their surroundings. During hibernation, frogs enter a state of reduced metabolic activity to conserve energy. This affects their respiratory system, and they rely on alternative methods of respiration.
The correct answer to the given question is A: Skin. Here's a detailed explanation:
Skin:
- During hibernation, frogs often burrow into soil or mud, which allows them to remain moist and maintain contact with water.
- Frogs have thin, permeable skin that allows for gas exchange with the environment.
- Oxygen can diffuse through the skin and into the bloodstream, while carbon dioxide can diffuse out.
- This method of respiration is effective in obtaining the necessary oxygen for the frog's reduced metabolic needs during hibernation.
To summarize, hibernating frogs primarily rely on respiration through their skin to obtain oxygen. This is because their metabolic rate is reduced, and they do not require as much oxygen as they would during their active state.

The syrinx is the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal folds of mammals. The sound is produced by vibrations of some or all of the membrana tympaniformis and the pessulus, caused by air flowing through the syrinx.

Lungs supported by 9 air sacs:


Explanation:
- The lungs of the following animal are supported by 9 air sacs: Pigeon.
- The presence of air sacs in the respiratory system of birds is an adaptation that allows for efficient gas exchange during flight.
- The air sacs act as additional respiratory organs, providing a continuous flow of air through the lungs.
- This continuous flow of air ensures a constant supply of oxygen and allows for the removal of carbon dioxide during flight.
- Pigeons are known for their ability to fly long distances, and the presence of 9 air sacs in their respiratory system helps facilitate this high level of activity.
- The air sacs in a pigeon's respiratory system are connected to the lungs and extend into various parts of their body, including the chest cavity and abdominal cavity.
- The air sacs also play a role in regulating body temperature and buoyancy during flight.
- Other animals, such as mammals like humans and cats, have different respiratory systems and do not possess the same adaptations as birds.
- Therefore, the correct answer is C: Pigeon.

Thyroid forms Adam's apple in Man.
The Adam's apple is a prominent feature in the neck area of adult men. It is caused by the thyroid cartilage, which is part of the larynx or voice box. Here is a detailed explanation of how the thyroid forms Adam's apple in men:
1. Thyroid Cartilage:
- The thyroid cartilage is a large piece of cartilage that is located at the front of the neck.
- It is shaped like a shield or a "V" and is more prominent in adult males.
2. Laryngeal Prominence:
- The thyroid cartilage has a protrusion in the front called the laryngeal prominence.
- This is what creates the visible Adam's apple.
3. Vocal Cord Protection:
- The Adam's apple serves as a protective shield for the vocal cords.
- It helps to protect the delicate structures of the larynx during swallowing and other activities.
4. Hormone Production:
- The thyroid gland, which is located in the neck, is responsible for producing hormones that regulate metabolism.
- The thyroid gland is situated just below the Adam's apple.
5. Gender Differences:
- The Adam's apple is generally more prominent in adult males than in females.
- This is because the larynx in males tends to grow larger during puberty, resulting in a more noticeable Adam's apple.
In conclusion, the thyroid cartilage forms the Adam's apple in men. It serves as a protective structure for the vocal cords and is more prominent in adult males due to hormonal and anatomical differences.

The number of lobes in the lungs of different animals:
- Squirrel: The lungs of a squirrel have __ lobes.
- Man: The lungs of a man have five lobes.
- Rabbit: The lungs of a rabbit have four lobes on the right lung and two lobes on the left lung.
Detailed explanation:
- Squirrel: The number of lobes in the lungs of a squirrel is not mentioned in the given information. Therefore, we cannot determine the exact number of lobes in squirrel lungs.
- Man: In humans, the lungs are divided into five lobes. The right lung has three lobes (superior, middle, and inferior lobes), while the left lung has two lobes (superior and inferior lobes).
- Rabbit: The lungs of a rabbit have a different lobar arrangement compared to humans. The right lung of a rabbit has four lobes (cranial, middle, caudal, and accessory lobes), while the left lung has two lobes (cranial and caudal lobes).
Conclusion:
Based on the given information, we can conclude that the lungs of a man have five lobes, whereas the number of lobes in squirrel lungs is not specified. The lungs of a rabbit have four lobes on the right lung and two lobes on the left lung.

The respiratory activities are regulated by:
A. Hormones:
- Hormones play a role in regulating various physiological processes in the body, but they do not directly regulate respiratory activities. They mainly regulate metabolic processes and the function of various organs and systems.
B. Vitamins:
- Vitamins are essential for the proper functioning of the body, including the respiratory system. However, they do not directly regulate respiratory activities. They are involved in various metabolic processes that support overall lung health.
C. Medulla oblongata:
- The medulla oblongata is a part of the brainstem that plays a crucial role in regulating respiratory activities. It contains the respiratory centers that control the rate and depth of breathing. The medulla oblongata receives input from chemoreceptors that detect changes in oxygen and carbon dioxide levels in the blood, as well as other sensory receptors that provide information about the body's needs.
D. None:
- This option is incorrect as the respiratory activities are indeed regulated by the medulla oblongata in the brainstem.
In conclusion, the correct answer is C: Medulla oblongata. This part of the brain regulates respiratory activities by controlling the rate and depth of breathing based on the body's needs and feedback from chemoreceptors.

The lungs of frogs are situated in the body cavity.
The body cavity of a frog is the central cavity that houses various organs, including the lungs. The lungs are responsible for respiration in frogs, allowing them to exchange oxygen and carbon dioxide with the environment.
Here are some key points to consider:
1. Body cavity: The body cavity of a frog is a spacious chamber that contains the internal organs. It is surrounded by the body wall and protected by the rib cage.
2. Lungs: Frogs have a pair of lungs that are located within the body cavity. The lungs are spongy organs that are responsible for the exchange of gases during respiration.
3. Respiration: Frogs primarily respire through their lungs, although they also have the ability to breathe through their skin. The lungs allow for the intake of oxygen and the release of carbon dioxide.
4. Thoracic cavity: While the lungs are situated within the body cavity, it is important to note that the body cavity can be further divided into specific regions. One such region is the thoracic cavity, which contains the heart and other thoracic organs, but not the lungs.
5. Pleural cavity: The pleural cavity is a subcompartment within the thoracic cavity that surrounds the lungs. It is lined by a membrane called the pleura and contains a small amount of fluid to reduce friction during breathing. However, in frogs, the lungs are not situated within the pleural cavity.
In conclusion, the lungs of frogs are situated in the body cavity, not the thoracic cavity or the pleural cavity. It is important to understand the anatomical structure of frogs to gain a better understanding of their respiratory system.

Respiratory Center Sensitivity
The respiratory center is a group of neurons located in the brainstem that controls the rate and depth of breathing. It is primarily sensitive to the levels of certain gases and chemicals in the blood. Among these, the respiratory center is particularly sensitive to the levels of carbon dioxide (CO2) in the blood.
Reasons for Respiratory Center Sensitivity to CO2
1. Chemoreceptors: The respiratory center contains chemoreceptors that detect changes in the levels of CO2 in the blood. These chemoreceptors are located in the carotid bodies and aortic bodies, which are specialized areas in the blood vessels that supply the brain and body with oxygenated blood. When the chemoreceptors detect an increase in CO2 levels, they send signals to the respiratory center to increase the rate and depth of breathing.
2. Chemical Reactions: Increased levels of CO2 in the blood lead to the formation of carbonic acid (H2CO3) through a chemical reaction. This reaction triggers an increase in the respiratory rate as the body attempts to remove the excess CO2 and restore the acid-base balance.
3. Respiratory Drive: The respiratory center uses the level of CO2 in the blood as a primary drive for breathing. When CO2 levels rise, it stimulates the respiratory center, leading to an increased respiratory rate and depth to expel the excess CO2 and maintain a healthy blood pH.
Other Factors:
While the respiratory center primarily responds to CO2 levels in the blood, it also takes into account other factors that affect respiration, such as:
- Oxygen (O2) levels: Low oxygen levels in the blood, known as hypoxemia, can also stimulate the respiratory center to increase breathing rate and depth. However, the sensitivity of the respiratory center to CO2 is greater than its sensitivity to O2.
- pH balance: Changes in blood pH can also influence the respiratory center's response. Acidosis (low blood pH) and alkalosis (high blood pH) can affect the respiratory rate, but the primary driver is still CO2 levels.
In conclusion, the respiratory center is primarily sensitive to CO2 levels in the blood. When CO2 levels rise, it stimulates the respiratory center to increase the rate and depth of breathing, allowing the body to expel excess CO2 and maintain a healthy blood pH.

Color of oxyhaemoglobin in man is


The color of oxyhaemoglobin in man is bright red. This is because oxyhaemoglobin is the form of hemoglobin that is bound to oxygen molecules and is found in red blood cells. When oxygen binds to hemoglobin, it causes a change in the shape of the molecule, giving it a bright red color. Here is a detailed explanation:
Explanation:
- Hemoglobin is a protein found in red blood cells that is responsible for carrying oxygen throughout the body.
- When oxygen molecules bind to hemoglobin, it forms oxyhaemoglobin.
- Oxyhaemoglobin is bright red in color.
- The bright red color of oxyhaemoglobin is due to the interaction between the iron atom in the heme group of hemoglobin and the oxygen molecule.
- This interaction causes a change in the shape of the molecule, resulting in the bright red color.
- The presence of oxygen in the bloodstream is vital for the body's oxygen supply to tissues and organs.
- When oxygen is released from oxyhaemoglobin in tissues, it becomes deoxyhaemoglobin, which has a darker red color.
- Deoxyhaemoglobin returns to the lungs where it picks up oxygen and becomes oxyhaemoglobin again.
- This continuous cycle of oxygen binding and release is crucial for maintaining the body's oxygen balance.
Therefore, the color of oxyhaemoglobin in man is bright red due to the binding of oxygen to hemoglobin in red blood cells.

Carbonic anhydrase is found in RBC.
- Carbonic anhydrase is an enzyme that catalyzes the reversible hydration of carbon dioxide (CO2) to bicarbonate ions (HCO3-) in red blood cells (RBC).
- RBCs play a crucial role in transporting oxygen and carbon dioxide in the body.
- The enzyme carbonic anhydrase helps to maintain the acid-base balance in the body by facilitating the conversion of CO2 to HCO3- in RBCs.
- The presence of carbonic anhydrase in RBCs allows for efficient transport of CO2 from the tissues to the lungs, where it can be eliminated.
- Carbonic anhydrase is not found in white blood cells (WBCs) or any other cell types.
- Therefore, the correct answer is option A: RBC.