Key Fact
Respiratory volumes
TV (tidal volume) ~500 mL; IRV ~3000 mL; ERV ~1100 mL; RV ~1200 mL. IC = TV + IRV; FRC = ERV + RV; VC = TV + IRV + ERV; TLC = VC + RV ~6000 mL.
-- NCERT Class 11 Biology, Chapter 14, p. 186Breathing Mechanism Volumes
8 MCQs4 revision cards9-step worked example
Source: NCERT Human PhysiologyPYQ coverage: NEET 2022, 2023, 2024Official key: NTA-verifiedLast updated: 24 Sep 2026
Breathing Mechanism Volumes, explained for NEET
The trap that costs marks on this topic: confusing which volumes are included in a capacity and which are excluded. Specifically, students write VC = TV + IRV and forget ERV — or worse, include RV in vital capacity.
The mechanism of breathing involves pressure changes driven by the diaphragm and external intercostal muscles. During inspiration, the diaphragm contracts (flattens), thoracic volume increases, intra-pulmonary pressure drops below atmospheric pressure, and air rushes in. Expiration at rest is largely passive — the diaphragm relaxes, elastic recoil of lungs raises intra-pulmonary pressure above atmospheric, and air is expelled (NCERT Class 11 Biology Chapter 14, page 185).
Respiratory volumes (measured by spirometry):
- Tidal Volume (TV): ~500 mL — air in a normal breath.
- Inspiratory Reserve Volume (IRV): ~3000 mL — extra air inhaled after normal inspiration.
- Expiratory Reserve Volume (ERV): ~1100 mL — extra air exhaled after normal expiration.
- Residual Volume (RV): ~1200 mL — air remaining after maximum expiration (cannot be measured by simple spirometry).
Capacities are sums of volumes:
- Vital Capacity (VC) = TV + IRV + ERV ≈ 4600 mL. Excludes RV.
- Total Lung Capacity (TLC) = VC + RV ≈ 5800 mL.
- Functional Residual Capacity (FRC) = ERV + RV ≈ 2300 mL.
- Inspiratory Capacity (IC) = TV + IRV ≈ 3500 mL.
Watch-out: VC is the maximum volume you can move — it never includes residual volume. If a question asks "which capacity includes RV?" — only TLC and FRC qualify.
Can you answer these Breathing Mechanism Volumes MCQs?
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
MCQ 1Easy RecallPractice
Which of the following is the approximate tidal volume in a healthy adult?
Show answer and why every option is right or wrong
Answer: D. Tidal volume is approximately 500 mL in a healthy adult at rest (NCERT Class 11 Biology Chapter 14, page 186).
Why A is wrong: A — 1100 mL is the value of expiratory reserve volume (ERV), not tidal volume.
Why B is wrong: B — 3000 mL is the inspiratory reserve volume (IRV), the additional air inhaled after normal inspiration.
Why C is wrong: C — 1200 mL is the residual volume (RV), the air that remains after forced expiration.
MCQ 2Easy RecallPractice
Residual volume is defined as the volume of air:
Show answer and why every option is right or wrong
Answer: A. Residual volume (~1200 mL) is the air that remains in the lungs even after the most forceful expiration (NCERT Class 11 Biology Chapter 14, page 187).
Why B is wrong: B — Air exhaled after normal expiration describes expiratory reserve volume (ERV).
Why C is wrong: C — Air inhaled after normal inspiration describes inspiratory reserve volume (IRV).
Why D is wrong: D — Air exchanged during normal breathing describes tidal volume (TV).
MCQ 3Easy RecallPractice
During normal quiet inspiration, which event occurs?
Show answer and why every option is right or wrong
Answer: D. During inspiration, external intercostal muscles contract, pulling the ribs upward and outward, increasing thoracic volume (NCERT Class 11 Biology Chapter 14, page 185).
Why A is wrong: A — Intra-pulmonary pressure drops BELOW atmospheric during inspiration; rising above atmospheric is what happens during expiration.
Why B is wrong: B — The diaphragm CONTRACTS (flattens) during inspiration; relaxation to dome shape occurs during expiration.
Why C is wrong: C — Internal intercostal muscles are involved in FORCED expiration, not inspiration.
MCQ 4Direct ApplicationPractice
Vital capacity (VC) of a person is 4600 mL. If IRV = 3000 mL and TV = 500 mL, what is the expiratory reserve volume?
Show answer and why every option is right or wrong
Answer: B. VC = TV + IRV + ERV. Therefore ERV = VC − TV − IRV = 4600 − 500 − 3000 = 1100 mL (NCERT Class 11 Biology Chapter 14, pages 186–187).
Why A is wrong: A — 1200 mL is the residual volume, not ERV. This error arises from confusing RV with ERV (trap: lung volume inclusions).
Why C is wrong: C — 2300 mL is the functional residual capacity (ERV + RV), not ERV alone.
Why D is wrong: D — 1600 mL results from incorrectly subtracting only IRV from VC (forgetting to subtract TV).
MCQ 5Direct ApplicationPractice
A student calculates vital capacity as TV + IRV = 3500 mL. What is the error?
Show answer and why every option is right or wrong
Answer: B. VC = TV + IRV + ERV. The student omitted ERV (~1100 mL). Vital capacity is the total exchangeable air excluding only the residual volume (NCERT Class 11 Biology Chapter 14, page 187).
Why A is wrong: A — TV is correctly included in VC; the formula VC = TV + IRV + ERV requires all three. Removing TV would be wrong.
Why C is wrong: C — RV is NEVER included in vital capacity. Adding RV would give TLC, not VC (trap: lung volume inclusions).
Why D is wrong: D — Both IRV and ERV must be included; replacing one with the other gives neither VC nor any standard capacity.
MCQ 6Direct ApplicationPractice
If TV = 500 mL, IRV = 3000 mL, ERV = 1100 mL, and RV = 1200 mL, what is the functional residual capacity (FRC)?
Show answer and why every option is right or wrong
Answer: C. FRC = ERV + RV = 1100 + 1200 = 2300 mL. FRC represents the air remaining in the lungs after a normal expiration (NCERT Class 11 Biology Chapter 14, page 187).
Why A is wrong: A — 4600 mL is the vital capacity (TV + IRV + ERV). FRC does not include TV or IRV.
Why B is wrong: B — 3500 mL is the inspiratory capacity (TV + IRV), not FRC.
Why D is wrong: D — 5800 mL is the total lung capacity (VC + RV), the sum of all volumes.
MCQ 7CalculationPractice
Given: TV = 500 mL, IRV = 3000 mL, ERV = 1100 mL, RV = 1200 mL. A student claims TLC = TV + IRV + ERV = 4600 mL. What is the correct TLC and what did the student confuse it with?
Show answer and why every option is right or wrong
Answer: A. TLC = VC + RV = (TV + IRV + ERV) + RV = 4600 + 1200 = 5800 mL. The student's answer of 4600 mL is actually VC, not TLC. They omitted RV (NCERT Class 11 Biology Chapter 14, pages 186–187).
Why B is wrong: B — Subtracting RV from any sum is not part of any standard capacity formula. TLC ADDS RV to VC, it does not subtract it.
Why C is wrong: C — 3500 mL is IC (TV + IRV), which is unrelated to the student's calculation of TV + IRV + ERV = 4600.
Why D is wrong: D — The student calculated VC (4600 mL), not TLC. TLC must include residual volume (trap: lung volume inclusions).
MCQ 8CalculationPractice
A spirometry report shows: IC = 3500 mL, ERV = 1100 mL, and RV = 1200 mL. Calculate both VC and TLC.
Show answer and why every option is right or wrong
Answer: C. IC = TV + IRV = 3500 mL. VC = IC + ERV = 3500 + 1100 = 4600 mL. TLC = VC + RV = 4600 + 1200 = 5800 mL (NCERT Class 11 Biology Chapter 14, pages 186–187).
Why A is wrong: A — 4700 mL would mean IC + RV, but VC = IC + ERV, not IC + RV. Confusing ERV with RV inflates both values by 100 mL.
Why B is wrong: B — This answer treats IC itself as VC (forgetting to add ERV) and then adds only RV to get TLC. VC must include ERV.
Why D is wrong: D — Correct VC but wrong TLC — this error omits RV from TLC, making TLC = VC, which defeats the definition of total lung capacity.
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Breathing Mechanism Volumes: quick recall before you leave
How do you solve a Breathing Mechanism Volumes question? A worked example
- 1
Given
IC = 3500 mL, ERV = 1100 mL, RV = 1200 mL
- 2
Required
Calculate (a) Vital Capacity and (b) Total Lung Capacity.
- 3
Concept
Lung capacities are defined sums of lung volumes. IC already contains TV + IRV. VC adds ERV to IC. TLC adds RV to VC.
- 4
Formula
VC = IC + ERV
TLC = VC + RV - 5
Substitution
VC = 3500 + 1100
TLC = VC + 1200 - 6
Calculation
VC = 4600 mL
TLC = 4600 + 1200 = 5800 mL
Note: All given values are standard textbook values treated as exact for this calculation. - 7
Final answer
VC = 4600 mL; TLC = 5800 mL
- 8
Common trap
Students often write VC = IC = 3500 mL, forgetting that IC does NOT include ERV. Vital capacity requires the expiratory reserve volume. Similarly, confusing TLC with VC (omitting RV) is a high-frequency error on this topic.
- 9
Similar NEET-style question
"If ERV = 1000 mL, TV = 500 mL, IRV = 2500 mL, and RV = 1100 mL, which of the following is the correct TLC?"
(Apply: VC = 500 + 2500 + 1000 = 4000; TLC = 4000 + 1100 = 5100 mL.)
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What to remember before solving Breathing Mechanism Volumes questions
Which Breathing Mechanism Volumes formulas do you need for NEET?
Respiratory volumes and capacities
Defines lung volumes and their sums (capacities). TV ~500 mL, IRV ~3000 mL, ERV ~1100 mL, RV ~1200 mL.
| Symbol | Quantity | SI Unit |
|---|---|---|
| TV | tidal | mL |
| IRV | inspiratory reserve | mL |
| ERV | expiratory reserve | mL |
| RV | residual | mL |
Valid when
- Normal adult resting
- Spirometry-measured (RV indirect)
Where do students lose marks on Breathing Mechanism Volumes?
These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Category: Similar Terms
Capacities are SUMS of volumes. VC = TV+IRV+ERV (excludes RV); TLC = VC+RV.
When it triggers
Question asks which capacity equals sum of which volumes.
How to avoid
VC excludes RV (residual is unmeasurable directly); TLC includes everything.
Root cause: formula misuse
Correction
Vital capacity is the maximum air a person can exhale after deepest inspiration. = Tidal + Inspiratory reserve + Expiratory reserve. Excludes residual.
More in Human Physiology: 31 exam traps and mistakes · 1 formula · 1 question pattern from its other lessons.
Breathing Mechanism Volumes questions from past NEET papers
3 questions from NEET 2022, 2023, 2024. Answers verified against NTA official keys.
NEET 2024Revised key
1A-II, B-IV, C-I, D-III
2A-III, B-II, C-IV, D-I
3A-II, B-I, C-IV, D-III
4A-I, B-III, C-II, D-IV
NTA Answer: Option 1(revised_final)
NEET 2023
Vital capacity of lung is _________.
1IRV + ERV + TV + RV
2IRV + ERV + TV – RV
3IRV + ERV + TV
4IRV + ERV
NTA Answer: Option 3(final)
NEET 2022
Which of the following is not observed during apoplastic pathway ?
1Apoplast is continuous and does not provide any barrier to water movement
2Movement of water occurs through intercellular spaces and wall of the cells
3The movement does not involve crossing of cell membrane
4The movement is aided by cytoplasmic streaming
NTA Answer: Option 4(final)
Sources
NCERT refs: Class 11 Biology Chapter 14, p.185
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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