Q.149 Zoology ⭐ 360° Option Elimination Active

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NEET 2026 Zoology Question 149 Solution

Topic: Body Fluids and Circulation · Official NTA Booklet Code 50

Question

The opening between the right atrium and the right ventricle is guarded by

(1)bicuspid valve
(2)tricuspid valve
(3)semilunar valve
(4)sino-atrial node

✓

Verified Against NTA Final Answer Key

Option (2) : tricuspid valve

📚 Body Fluids and Circulation Easy

📋 Given Parameters & Problem Setup

Cardiac Aperture Opening between right atrium and right ventricle

Anatomical Structure Valve guarding this atrioventricular orifice

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The 30-Second Exam Hall Shortcut: ⚡ Right = Tri; Left = Bi (MitrAL) Rule

⏱️ Save ~40 seconds

Right AV opening = TRICUSPID valve; Left AV opening = BICUSPID (Mitral) valve!

1 Recall anatomical valve rule:

2 Right atrioventricular orifice = guarded by 3 muscular flaps -> TRICUSPID valve.

3 Left atrioventricular orifice = guarded by 2 muscular flaps -> BICUSPID (Mitral) valve.

4 Semilunar valves guard pulmonary artery and aorta openings.

5 The question specifies "between right atrium and right ventricle".

6 Select Option (2) Tricuspid valve in 3 seconds!

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Body Fluids and Circulation (Cardiac Cycle: Stroke volume x Heart rate = Cardiac output of ~5 L/min).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Anatomy of Human Heart Valves

The human heart possesses four chambers: two atria and two ventricles. To ensure unidirectional blood flow and prevent backflow during ventricular systole, the atrioventricular apertures are guarded by specialized fibrous valves.

\text{AV Valves} = \begin{cases} \mathbf{Right\text{ Atrium - Right Ventricle}} &: \mathbf{Tricuspid\text{ Valve (Three flaps/cusps)}} \\ \text{Left Atrium - Left Ventricle} &: \text{Bicuspid / Mitral Valve (Two flaps/cusps)} \end{cases}

• NCERT verbatim: "The opening between the right atrium and the right ventricle is guarded by a valve formed of three muscular flaps or cusps, the tricuspid valve."

Step 2

Evaluate Other Named Structures

Bicuspid (mitral) valve guards the left atrioventricular aperture. Semilunar valves guard the openings of the right ventricle into the pulmonary artery and left ventricle into the systemic aorta. The sino-atrial node (SAN) is the neuromuscular pacemaker patch, not a mechanical valve.

\text{Right AV Valve} = \mathbf{Tricuspid\text{ Valve}} \implies \text{Option (2)}

• Option (2) is the solely accurate response.

Step 3

Conclusion

The tricuspid valve guards the right atrioventricular aperture.

\text{Correct Valve} = \text{Option (2)}

• Matches official NTA final answer key Option B / (2).

⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 A

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Bicuspid (mitral) valve guards the opening between the left atrium and left ventricle.

⚠️

Student Fallacy (Why candidates pick this trap): Swapping right and left cardiac valves.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

100% accurate. The right atrioventricular opening is guarded by the tricuspid valve.

💡

Why this is airtight: None; standard direct anatomical recall.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Semilunar valves guard the pulmonary and aortic outflow tract exits, not the atrioventricular orifices.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing arterial outflow valves with atrioventricular valves.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. SAN is the electrical pacemaker tissue located in the right atrial wall, not a valve.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing conducting nodal tissue with heart valves.

⚠️

NTA Trap Alert: Bicuspid vs Tricuspid Lateralization

Under exam pressure, students frequently forget whether Tricuspid is on the right or the left side of the heart.

🛡️ How to avoid the -1 mark: Remember: Try to be Right (TRIcuspid = RIGHT)!

📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Body Fluids and Circulation Standard Benchmark

Core Scientific Principle Tested:

"The right atrioventricular aperture is guarded by the tricuspid valve; the left atrioventricular aperture is guarded by the bicuspid (mitral) valve."

Syllabus Focus: Circulatory Pathways - Human Circulatory System Anatomy

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

TRI to be RIGHT: TRICUSPID is on the RIGHT; BI is on the LEFT!

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NEET 2026 Zoology Question 149 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Right = Tri; Left = Bi (MitrAL) Rule

Step-by-Step Rigorous Workflow & Mathematical Proof

Anatomy of Human Heart Valves

Evaluate Other Named Structures

Conclusion

360° Option Elimination Engine Key Feature

NTA Trap Alert: Bicuspid vs Tricuspid Lateralization

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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