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Q.94 Botany ⭐ 360° Option Elimination Active
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NEET 2025 Botany Question 94 Solution

Topic: Structural Organisation in Animals · Official NTA Booklet Code 45
NEET 2025 Botany Question 94: Blood Vessels Returning Deoxygenated Blood to the Heart in Frog

Question

What is the name of the blood vessel that carries deoxygenated blood from the body to the heart in a frog?

  1. (1)Aorta
  2. (2)Pulmonary artery
  3. (3)Pulmonary vein
  4. (4)Vena cava
✓
Verified Against NTA Final Answer Key
Option (4) : Vena cava
📚 Structural Organisation in Animals Easy
📋 Given Parameters & Problem Setup
Organism Frog (Rana tigrina)
Blood Type Deoxygenated blood
Direction of Flow From body tissues returning to the heart
⚡

The 30-Second Exam Hall Shortcut: ⚡ Amphibian Venous Return Rule

⏱️ Save ~20 seconds

Aorta carries oxygenated blood AWAY from heart. Pulmonary artery carries blood TO lungs. Pulmonary vein carries oxygenated blood FROM lungs. Deoxygenated blood from the body is collected by major veins called VENA CAVA (caval veins) into the sinus venosus! ⟹ Vena cava!

1 Recall frog vascular system: Blood from all body parts is returned to the heart by veins.
2 Major veins from the anterior and posterior body regions are the venae cavae (two precavals and one postcaval).
3 These vena cava vessels pour deoxygenated blood into a triangular sac called sinus venosus, which in turn empties into the right atrium.
4 Contrast with alternatives:
5 - Aorta: Large arterial trunk distributing oxygenated/mixed blood to body tissues.
6 - Pulmonary artery: Carries deoxygenated blood to lungs.
7 - Pulmonary vein: Carries oxygenated blood from lungs to left atrium.
8 Match Option (4) Vena cava in under 5 seconds!
🛡️
Why You Can 100% Trust This Shortcut: Anuran Urogenital Anatomy (NCERT Biology · Structural Organisation in Animals: Ureters act as urinogenital ducts in male frogs).
📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Circulatory System of Frog (Rana tigrina)

The vascular system of frog is closed, complete, and contains a three-chambered heart (two atria and one ventricle):

Body Tissues→Deoxygenated bloodVena cava⟶Sinus venosus⟶Right Atrium\text{Body Tissues} \xrightarrow{\text{Deoxygenated blood}} \text{Vena cava} \longrightarrow \text{Sinus venosus} \longrightarrow \text{Right Atrium}
  • • Deoxygenated blood from the head, forelimbs, and body is collected by the anterior and posterior vena cava.
Step 2

Contrast with Other Vessels

Evaluate the physiological role of the other options:

Aorta: Arterial distribution,Pulmonary Vein: Oxygenated return from lungs\text{Aorta: Arterial distribution}, \quad \text{Pulmonary Vein: Oxygenated return from lungs}
  • • Aorta delivers systemic blood outward from the conus arteriosus.
  • • Pulmonary veins carry oxygen-rich blood from the lungs into the left atrium.
  • • Pulmonary arteries transport blood from heart to lungs for oxygenation.
  • • Therefore, the vessel carrying deoxygenated blood from body to heart is the Vena cava, matching Option (4).
⭐

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. The aorta is an artery that transports blood away from the heart to the body.

⚠️
Student Fallacy (Why candidates pick this trap): Confusing arteries with veins.
2 B
✗ Incorrect
Verdict & Scientific Reason:

Incorrect. Carries blood from the heart to the lungs.

⚠️
Student Fallacy (Why candidates pick this trap): Thinking pulmonary artery drains the body.
3 C
✗ Incorrect
Verdict & Scientific Reason:

Incorrect. Carries oxygenated blood from lungs to heart.

⚠️
Student Fallacy (Why candidates pick this trap): Confusing pulmonary vein with systemic veins.
4 D
✓ 100% Correct
Verdict & Scientific Reason:

100% correct. Deoxygenated blood from the body is collected by the vena cava into sinus venosus.

💡
Why this is airtight: None; textbook anatomical recall.
⚠️

NTA Trap Alert: Confusing Sinus Venosus with Vena Cava

Sinus venosus is the receiving heart chamber, whereas VENA CAVA is the actual blood vessel that collects and transports deoxygenated blood from the body into the sinus venosus!

🛡️ How to avoid the -1 mark: The question asks for the "BLOOD VESSEL", which is Vena cava.
📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Structural Organisation in Animals Standard Benchmark
Core Scientific Principle Tested:

"Deoxygenated blood from body tissues enters the heart via the vena cava and sinus venosus."

Syllabus Focus: Frog Anatomy: Blood Vascular System
✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗
Body to Heart = Vena Cava (Vein Caves into heart) ⟹ Option (4)!

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