Frog Anatomy

8 MCQs9-step worked example
Source: NCERT Biological ClassificationPYQ coverage: NEET 2020, 2021, 2022, 2023, 2024, 2025Official key: NTA-verifiedLast reviewed: May 2026

Lesson

Frog anatomy is a recurring NEET topic that tests whether you can correctly match organs, structures, and systems to their specific locations and functions in Rana tigrina (Indian bull frog). The common confusion: mixing up features across organ systems — placing the sinus venosus in the arterial side, confusing the hepatic portal system with the renal portal system, or swapping sensory cranial nerves.

External morphology. The frog body divides into head and trunk (no neck, no tail in adult). Skin is smooth, moist, and permeable — functions in cutaneous respiration. The dorsal side is olive green (camouflage); ventral side is pale yellow. The tympanum (external ear) sits behind each eye. Forelimbs have four digits; hindlimbs have five webbed digits (NCERT Class 11 Biology Chapter 7, page 144).

Digestive system. Mouth → buccal cavity (with bilobed tongue attached anteriorly, free posteriorly — flips out to catch prey) → oesophagus → stomach → duodenum → ileum → rectum → cloaca. Liver secretes bile stored in the gall bladder; pancreas lies between stomach and duodenum.

Circulatory system. Three-chambered heart: two atria + one ventricle. The sinus venosus receives deoxygenated blood and opens into the right atrium. Conus arteriosus arises from the ventricle. The hepatic portal system carries blood from intestine to liver; the renal portal system carries blood from lower body to kidneys. RBCs are nucleated and biconvex.

Nervous system. Brain has forebrain (olfactory lobes, cerebral hemispheres), midbrain (optic lobes), and hindbrain (cerebellum, medulla oblongata). Ten pairs of cranial nerves. Spinal cord with spinal nerves.

Watch out: NEET frequently tests portal systems (hepatic vs renal), tongue attachment (anterior, not posterior), heart chamber count, and the number of cranial nerves (10, not 12 — that is mammals).

Practice 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

How many pairs of cranial nerves are present in a frog?

MCQ 2Easy RecallPractice

The tympanum in a frog is located:

MCQ 3Easy RecallPractice

The tongue of a frog is attached at the:

MCQ 4Direct ApplicationPractice

A student observes nucleated, biconvex red blood cells in a blood smear. The sample most likely belongs to:

MCQ 5Direct ApplicationPractice

Blood from the intestine of a frog travels to the liver before reaching the heart. This pathway is called the:

MCQ 6Direct ApplicationPractice

The sinus venosus in a frog's heart receives blood and opens into the:

MCQ 7Concept TrapPractice

A frog can respire through its skin even when submerged underwater. Which property of frog skin makes this possible?

MCQ 8CalculationPractice

A frog's heart has two atria and one ventricle. The conus arteriosus distributes blood from the ventricle to different arteries. If the conus arteriosus were absent, which of the following would be the most direct consequence?

Worked Example

  1. 1

    Given

    A question states: "In a frog, the portal system that carries blood from the hind limbs to the kidneys before it returns to the heart is called ___." Four options are offered: - A. Hepatic portal system - B. Renal portal system - C. Pulmonary portal system - D. Systemic portal system

  2. 2

    Required

    Identify which portal system connects the hind limbs/lower body to the kidneys.

  3. 3

    Concept

    Frogs possess two portal systems. A portal system is a venous pathway where blood passes through two capillary beds before returning to the heart. The hepatic portal system routes intestinal blood through the liver. The renal portal system routes blood from the posterior body through the kidneys.

  4. 4

    Formula

    No formula applies — this is a recall-and-apply concept question. The key mapping: - Intestine → Liver = Hepatic portal - Hind limbs → Kidneys = Renal portal

  5. 5

    Substitution

    The question specifies "hind limbs to kidneys." Match to: Renal portal system.

  6. 6

    Calculation

    No calculation. Direct conceptual matching.

  7. 7

    Final answer

    **B. Renal portal system.**

  8. 8

    Common trap

    The most common error is selecting "Hepatic portal system" because students remember "portal system" and default to the more frequently discussed hepatic version. The word "hepatic" (liver) vs "renal" (kidney) is the distinguishing cue — read the destination organ in the stem.

  9. 9

    Similar NEET-style question

    "The blood from the digestive tract of a frog reaches the liver through the ___." (Answer: Hepatic portal system — the mirror question testing the same two-portal mapping.) ---

Before solving, remember these

Key Fact

Frog — anatomy overview

Frog (*Rana tigrina*): poikilothermic; smooth, moist skin (cutaneous respiration); two-chambered atrium + one ventricle; mesonephric kidney; urinogenital duct in male; cleidoic egg in some species.

-- NCERT Class 11 Biology, Ch. 7, p. 144

Exam Traps & Common Mistakes

These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.

Trap

Dicot vs monocot stem feature confusion

Category: Similar Terms

Dicot stem: vascular bundles in ring, conjoint, OPEN (cambium present), endarch. Monocot: scattered, CLOSED (no cambium), endarch.

When it triggers

Question shows TS or asks bundle arrangement.

How to avoid

Ring + cambium = dicot (open); scattered + no cambium = monocot (closed).

Trap

Epithelial tissue type and location swap

Category: Similar Terms

Squamous (alveoli, blood vessel lining), cuboidal (kidney tubules), columnar (intestine), ciliated (trachea/bronchi), glandular (sweat).

When it triggers

Question gives location and asks tissue type or vice versa.

How to avoid

Map: shape → function — squamous = thin diffusion; columnar = absorption; ciliated = movement.

Trap

Placentation type confusion (axile vs parietal)

Category: Similar Terms

Marginal (peas), axile (china rose, lemon), parietal (mustard), free central (Dianthus), basal (sunflower).

When it triggers

Question gives plant family/example and asks placentation.

How to avoid

Memorise per family: Solanaceae axile; Brassicaceae parietal; Fabaceae marginal.

Mistake

Confuses valvate, twisted, and imbricate aestivation.

Root cause: term confusion

Correction

Valvate: edges touch (Calotropis). Twisted: one edge overlaps next (China rose). Imbricate: irregular overlap (Cassia). Vexillary: papilionaceous (pea — flag-like standard).

Past Year Questions

47 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025. Answers verified against NTA official keys.

NEET 2024

Bulliform cells are responsible for

1Inward curling of leaves in monocots.
2Protecting the plant from salt stress.
3Increased photosynthesis in monocots.
4Providing large spaces for storage of sugars.
NTA Answer: Option 1(final)
NEET 2024

Match List I with List II related to digestive system of cockroach. List-I List-II A. The structures used for I. Gizzard storing of food. B. Ring of 6-8 blind tubules II. Gastric Caeca at junction of foregut and midgut. C. Ring of 100-150 yellow III. Malpighian tubules coloured thin filaments at junction of midgut and hindgut. - 51 - NEET (UG)-2024 (Code-Q3) D. The structures used for IV. Crop grinding the food. Choose the correct answer from the options given below:

1A-IV, B-II, C-III, D-I
2A-I, B-II, C-III, D-IV
3A-IV, B-III, C-II, D-I
4A-III, B-II, C-IV, D-I
NTA Answer: Option 1(final)
NEET 2023

Given below are two statements : Statement I : Endarch and exarch are the terms often used for describing the position of secondary xylem in the plant body. Statement II : Exarch condition is the most common feature of the root system. In the light of the above statements, choose the correct answer from the options given below:

1Both Statement I and Statement II are false
2Statement I is correct but Statement II is false
3Statement I is incorrect but Statement II is true
4Both Statement I and Statement II are true
NTA Answer: Option 3(final)
NEET 2023

Given below are two statements : Statement I : The forces generated transpiration can lift a xylem-sized column of water over 130 meters height. Statement II : Transpiration cools leaf surfaces sometimes 10 to 15 degrees evaporative cooling. In the light of the above statements, choose the most appropriate answer from the options given below :

1Both Statement I and Statement II are incorrect
2Statement I is correct but Statement II is incorrect
3Statement I is incorrect but Statement II is correct
4Both Statement I and Statement II are correct
NTA Answer: Option 4(final)
NEET 2023

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R : Assertion A : Late wood has fewer xylary elements with narrow vessels. Reason R : Cambium is less active in winters. In the light of the above statements, choose the correct answer from the options given below :

1Both A and R are true but R is NOT the correct explanation of A
2A is true but R is false
3A is false but R is true
4Both A and R are true and R is the correct explanation of A
NTA Answer: Option 4(final)
NEET 2023

Match List I with List II. List I (Type of Joint) List II (Found between) A. Cartilaginous Joint I. Between flat skull bones B. Ball and Socket Joint II. Between adjacent vertebrae in vertebral column C. Fibrous Joint III. Between carpal and metacarpal of thumb D. Saddle Joint IV. Between Humerus and Pectoral girdle Choose the correct answer from the options given below:

1A-II, B-IV, C-I, D-III
2A-I, B-IV, C-III, D-II
3A-II, B-IV, C-III, D-I
4A-III, B-I, C-II, D-IV
NTA Answer: Option 1(final)
NEET 2023

Which of the following statements are correct regarding skeletal muscle? A. Muscle bundles are held together by collagenous connective tissue layer called fascicle. B. Sarcoplasmic reticulum of muscle fibre is a store house of calcium ions. C. Striated appearance of skeletal muscle fibre is due to distribution pattern of actin and myosin proteins. D. M line is considered as functional unit of contraction called sarcomere. Choose the most appropriate answer from the options given below:

1B and C only
2A, C and D only
3C and D only
4A, B and C only
NTA Answer: Option 1(final)
NEET 2022

Read the following statements about the vascular bundles : (a) In roots, xylem and phloem in a vascular bundle are arranged in an alternate manner along the different radii. (b) Conjoint closed vascular bundles do not possess cambium (c) In open vascular bundles, cambium is present in between xylem and phloem (d) The vascular bundles of dicotyledonous stem possess endarch protoxylem (e) In monocotyledonous root, usually there are more than six xylem bundles present Choose the correct answer from the options given below :

1(a), (c), (d) and (e) Only
2(a), (b) and (d) Only
3(b), (c), (d) and (e) Only
4(a), (b), (c) and (d) Only Answer (NA) No option is correct 106. DNA polymorphism forms the basis of : (1) Translation (2) Genetic mapping (3) DNA finger printing (4) Both genetic mapping and DNA finger printing
NTA Answer: Option 4(final)
NEET 2022

In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to : (a) secretion of secondary metabolities and their deposition in the lumen of vessels. (b) deposition of organic compounds like tannins and resins in the central layers of stem. (c) deposition of suberin and aromatic substances in the outer layer of stem. (d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem. (e) presence of parenchyma cells, functionally active xylem elements and essential oils. Choose the correct answer from the options given below:

1(b) and (d) Only
2(a) and (b) Only
3(c) and (d) Only
4(d) and (e) Only
NTA Answer: Option 2(final)
NEET 2022

The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood. (a) It is also called as the earlywood (b) In spring season cambium produces xylem elements with narrow vessels (c) It is lighter in colour (d) The springwood along with autumnwood shows alternate concentric rings forming annual rings (e) It has lower density Choose the correct answer from the options given below :

1(c), (d) and (e) Only
2(a), (b), (d) and (e) Only
3(a), (c), (d) and (e) Only
4(a), (b) and (d) Only
NTA Answer: Option 3(final)
NEET 2022

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Osteoporosis is characterised by decreased bone mass and increased chance of fractures. Reason (R): Common cause of osteoporosis is increased levels of estrogen. In the light of the above statements, choose the most appropriate answer from the options given below.

1(A) is not correct but (R) is correct
2Both (A) and (R) are correct and (R) is the correct explanation of (A)
3Both (A) and (R) are correct but (R) is not the correct explanation of (A)
4(A) is correct but (R) is not correct
NTA Answer: Option 4(final)
NEET 2022

Given below are two statements: Statements I : In a scrubber the exhaust from the thermal plant is passed through the electric wires to charge the dust particles. Statement II : Particulate matter (PM 2.5) cannot be removed by scrubber but can be removed by an electrostatic precipitator. In the light of the above statements, choose the most appropriate answer from the options given below :

1Statement I is incorrect but Statement II is correct
2Both Statement I and Statement II are correct
3Both Statement I and Statement II are incorrect
4Statement I is correct but Statement II is incorrect
NTA Answer: Option 1(final)
NEET 2021

Match List-I with List-II. (4) Extension, Denaturation, Annealing Answer (2) List-I List-II 116. When gene targetting involving gene amplification is (a) Lenticels (i) Phellogen attempted in an individual's tissue to treat disease, (b) Cork cambium (ii) Suberin deposition it is known as :

1Safety testing (c) Secondary cortex (iii) Exchange of gases
2Biopiracy (d) Cork (iv) Phelloderm
3Gene therapy Choose the correct answer from the options given
4Molecular diagnosis below.
NTA Answer: Option 3(final)
NEET 2021

Match Column-I with Column-II (a) % K C A G (i) Brassicaceae 150. Now a days it is possible to detect the mutated gene (5) 1+2+(2) (9)+1 1 causing cancer by allowing radioactive probe to (b) K (5) C (5) A 5 G 2 (ii) Liliaceae hybridise its complimentary DNA in a clone of cells, followed by its detection using autoradiography (c) P A G (iii) Fabaceae because : (3 + 3) 3 + 3 (3)

1mutated gene does not appear on photographic (d) K C A G (iv) Solanaceae 2 + 2 4 2 – 4
2film as the probe has complementarity with it Select the correct answer from the options given (2) mutated gene partially appears on a below. photographic film (a) (b) (c) (d)
3mutated gene completely and clearly appears on (1) (iv) (ii) (i) (iii) a photographic film (2) (iii) (iv) (ii) (i)
4mutated gene does not appear on a (3) (i) (ii) (iii) (iv) photographic film as the probe has no complementarity with it (4) (ii) (iii) (iv) (i)
NTA Answer: Option 4(final)
NEET 2020

ÁŸêŸ Sà ÷Ê ∑§Ê Á◊‹ÊŸ ∑§⁄U ‚„Ë Áfl∑§À¬ ∑§Ê øÿŸ ∑§⁄UÊ – second and Sà ÷ - I Sà ÷ - II seventh ribs (a) å‹ÊflË ¬‚Á‹ÿÊ° (i) ŒÍ‚⁄UË ∞fl ‚ÊÃflË (b) Acromion (ii) Head of the ¬‚‹Ë ∑ § ’Ëø ÁSÕà Humerus „Ê ÃË „Ò (c) Scapula (iii) Clavicle (b) ∞∑§˝ÊÁ ◊ÿŸ (ii) sÍ◊⁄U‚ ∑§Ê ‡ÊË ¸ (c) S∑Ò§¬È‹Ê (iii) Ä‹ Áfl∑§‹ (d) Glenoid cavity (iv) Do not connect (d) Ç‹ËŸÊÚÿ«U ªÈ„Ê (iv) ©⁄UÊ ÁSÕ ‚ Ÿ„Ë ¡È«∏ÃË with the sternum (a) (b) (c) (d) (a) (b) (c) (d)

1(iv) (iii) (i) (ii) (1) (iv) (iii) (i) (ii)
2(ii) (iv) (i) (iii) (2) (ii) (iv) (i) (iii)
3(i) (iii) (ii) (iv) (3) (i) (iii) (ii) (iv)
4(iii) (ii) (iv) (i) (4) (iii) (ii) (iv) (i) H3 28 Hindi+English
NTA Answer: Option 1(final)

How NEET usually asks this

Recurring question shapes from past papers. Each pattern shows why wrong options look tempting.

Sources

NCERT refs: Class 11 Biology Chapter 7, p.144

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