Respiration

Step 1: Understanding Respiratory Volumes and Capacities:
Respiratory capacities are combinations of two or more respiratory volumes. We need to identify the term for the volume of air present in the lungs at the end of a normal (tidal) expiration.
Step 2: Analyzing the Definitions:

• Tidal Volume (TV): Volume of air inspired or expired during normal respiration ( ml).
• Residual Volume (RV): Volume of air remaining in the lungs even after a forcible expiration ( ml).
• Expiratory Reserve Volume (ERV): Additional volume of air that can be forcibly expired after a normal expiration ( ml).
• Vital Capacity (VC): Maximum volume of air a person can breathe in after a forced expiration ( ).

Step 3: Calculating the Volume after Normal Expiration:
When a person exhales normally, they expel the Tidal Volume. The air left inside consists of the air that \could be exhaled forcibly (ERV) plus the air that \cannot be exhaled (RV). This sum is defined as the Functional Residual Capacity (FRC).
Step 4: Final Answer:
The correct term is Functional Residual Capacity.

Step 1: Analyze the Nervous System:
The cockroach has a ventral nerve cord with segmental ganglia:

• Thorax: 3 ganglia (T1, T2, T3).
• Abdomen: 6 ganglia (A1 to A6).

Step 2: Explain the 6th Ganglion:
The first 5 abdominal ganglia correspond to the first 5 abdominal segments. However, the last ganglion (the 6th one), located in the 7th segment, is a compound ganglion. It is formed by the fusion of the neuromeres of the 7th, 8th, 9th, and 10th abdominal segments. Because it represents the fusion of multiple ganglia, it is physically the largest among the abdominal ganglia.
Step 3: Conclusion:
The Assertion is true (it is the largest). The Reason is true (formed by fusion) and correctly explains \why it is the largest.

Turbinals (conchae) are bony structures in the nasal cavity that support the respiratory region, increasing surface area for air filtration, humidification, and warming.

• Residual volume is the air remaining in lungs after maximal expiration.
• Tidal volume = normal breathing volume.
• Inspiratory reserve volume = additional air inhaled after normal inhalation.
• Expiratory reserve volume = additional air exhaled after normal exhalation.
• Hence correct answer: Residual volume.

The correct alimentary canal sequence of cockroach is: Oesophagus (VII) → Crop (III) → Gizzard (IV) → Ileum (V) → Mesenteron (II) → Colon (I) → Rectum (VI).

Concept: Classification of insect respiratory systems is based on the number of functional spiracles.
Explanation: A **polypneustic** (or holopneustic) system is characterized by having many functional spiracles. The cockroach has 10 pairs of functional spiracles, confirming that (A) is true. The Reason (R) correctly explains this: the functionality of all spiracles makes it polypneustic.