Problem 101 - Objective Biology for NEET

Question

A (1) sensitive area is situated adjacent to the rhythm centre which is highly sensitive to \((2)_{-}\) and \(_{-}(3) \longrightarrow\) ions. (a) (1)-thermo, (2)- CO \(_{2}\), (3)- hydroxide (b) (1)-chemo, (2) - \(\mathrm{O}_{2}\), (3)-hydroxide (c) (1)-thigmo, (2) \(-\mathrm{O}_{2}\), (3)- -hydrogen (d) (1)-chemo, (2) \(-\mathrm{CO}_{2}\), (3)-hydrogen

Step-by-Step Solution

Answer

The correct answer is (a). A 'chemo' sensitive area is situated adjacent to the rhythm centre which is highly sensitive to CO\(_{2}\) and hydroxide ions.

Step 1: Identify area (1)

Looking at the options, (1) could refer to either a 'thermo,' 'chemo,' or 'thigmo' sensitive area. Analyzing the context, it is clear that the area being referred to is sensitive to certain ions, which means it responds to chemical stimuli. Consequently, the correct term is 'chemo'.

Step 2: Identify ion (2)

Now, consider the ion \((2)_{-}\). Looking at the options, it could be either CO\(_{2}\) or O\(_{2}\). Given that it is referred to as a negatively charged ion in the original exercise (thus, containing an extra electron), the ion is CO\(_{2}\). O\(_{2}\) or oxygen does not carry a negative charge.

Step 3: Identify ion (3)

In a similar manner, the ion \(_{-}(3)\) has to be analyzed. Considering the options, it could be a hydroxide or a hydrogen ion. As it is in the form of \(_{-}(3)\), meaning it has an extra electron, the ion cannot be hydrogen, which is a positive ion. Therefore, the ion here is hydroxide, which carries a negative charge.

Key Concepts

Chemoreceptors

Chemoreceptors are specialized sensory receptors that respond to chemical changes in the environment. These changes often occur in the blood or external areas of the body. Chemoreceptors play a crucial role in maintaining homeostasis by detecting variations in the chemical components such as oxygen (O₂), carbon dioxide (CO₂), and hydrogen ions (H⁺).

When chemoreceptors detect high levels of certain chemicals, like CO₂, they send signals to the brain to adjust breathing rates or other physiological responses. This process helps maintain the correct balance of gases in the body. - They are located in areas like the carotid bodies and aortic arch. - They help regulate cardiovascular and respiratory systems. - Chemoreceptors can activate responses through neural pathways connected to the central nervous system.

The sensitive area adjacent to the rhythm center mentioned in the exercise refers to chemoreceptors, indicating their role in sensing ions and chemical stimuli, which adjusts the body's response appropriately.

CO2 Sensitivity

Carbon dioxide (CO₂) sensitivity refers to the body's ability to detect and respond to changes in CO₂ levels in the blood. This sensitivity is primarily mediated by chemoreceptors, which are sensitive to fluctuations in blood gas levels. Increased CO₂ levels lead to a drop in blood pH, making the blood more acidic.

The body reacts to increased CO₂ levels by: - Stimulating the respiratory center to increase the rate and depth of breathing. - Expelling more CO₂ through exhalation to restore normal levels. - Modifying heart rate to adjust to the changing demands for oxygen.

The receptors coordinate these responses to maintain an optimal balance of oxygen and carbon dioxide, keeping blood pH within its narrow range. CO₂ sensitivity ensures swift responses to dynamic changes, crucial for survival.

Hydroxide Ions

Hydroxide ions (OH⁻) are negatively charged ions formed when water dissociates partially or when under alkaline conditions. They are critical players in maintaining the pH balance in biological systems. Hydroxide ions act as a fundamental element in neutralizing acids, ensuring that environments do not become too acidic.

In the context of cellular respiration and chemical interactions, hydroxide ions might affect enzyme activity or ion transport. These processes are sensitive to pH changes, which hydroxide ions influence. - They help maintain the body's pH level through buffering systems. - These ions can counteract acidic conditions by neutralizing hydrogen ions (H⁺), making environments less acidic. - They contribute to processes like digestion and cellular metabolism.

Balancing hydroxide and hydrogen ions is essential for the proper functioning of cells and tissues, ensuring the body's overall health and stability.