Biology · Structural Organisation in Animals · NEET
Only the MALE frog has two special features: sound-producing vocal sacs and a copulatory pad on the FIRST digit of the fore limb. Both are absent in the female frog. Memory hook: "Boy frog can talk (vocal sacs) and hold (copulatory pad on finger 1)" - the girl frog does neither.
Male frog shows two extra features - vocal sacs (loud croak) and a copulatory pad on the first digit of the fore limb; the female has neither. Shared features like bulging eyes and webbed feet cannot tell the sexes apart.
Your doubts, answered
Which frog has the vocal sacs - male or female?
Only the MALE frog has vocal sacs. They are absent in the female. The male uses them to make loud sounds (croaking) to call the female during the breeding season. Female frogs cannot make this loud sound because they have no vocal sacs.
On which digit is the copulatory pad found?
The copulatory pad is present on the FIRST digit of the FORE limb (front leg) of the male frog only. NCERT is very exact here. A common trap is 'first digit of hind limb' - that is WRONG. Remember: first digit, fore limb, male only.
What is the function of the copulatory pad?
During mating (amplexus), the male frog climbs on the back of the female and holds her tightly. The copulatory pad is a rough, swollen pad on the first finger of the fore limb that helps the male grip the female firmly so she is not released while eggs and sperms are shed into water.
Do female frogs have any of these two features?
No. The female frog has NEITHER vocal sacs NOR a copulatory pad. Both features are used to mark sexual dimorphism - the male has them, the female does not. Other body features (bulging eyes, webbed feet, olive-green skin with spots) are common to both sexes.
Are vocal sacs the same as the sound the frog makes?
Vocal sacs are the structures (loose skin pouches) that fill with air and act like a balloon to amplify sound. The croaking sound is produced when air is pushed over the vocal cords, and the vocal sacs make it louder. Only the male frog has these sacs, so only the male croaks loudly.
⚠️ The NEET trap ✗ The copulatory pad is on the first digit of the HIND limb. ✓ The copulatory pad is on the FIRST digit of the FORE limb (front leg) of the male frog. 🧠 NTA loves swapping fore limb with hind limb. NCERT says FORE limb, first digit. Fore = front = the arm the male uses to grip the female.
Real NEET questions
NEET 2025
Which of the following statement is correct about location of the male frog copulatory pad?
A · Second digit of fore limb
B · First digit of the fore limb ✓
C · First and Second digit of fore limb
D · First digit of hind limb
Solution: Male frogs bear a copulatory pad on the FIRST digit of the FORE limbs (along with sound-producing vocal sacs), both absent in females. NCERT Class XI, Ch 7, p.81: 'a copulatory pad on the first digit of the fore limbs which are absent in female frogs.' Options with hind limb or second digit are traps.
NEET 2026
Male frogs can be distinguished from female frogs due to the presence of - A. Bulging eyes B. Vocal sacs C. Webbed digits in feet D. Copulatory pad on first digit of fore limbs E. Olive green-coloured skin with dark irregular spots
A · A and C only
B · A and E only
C · B and C only
D · B and D only ✓
Solution: Only vocal sacs (B) and the copulatory pad on the first digit of the fore limbs (D) are male-only features. Bulging eyes (A), webbed feet (C) and olive-green skin with spots (E) are common to BOTH sexes, so they cannot distinguish male from female. Correct answer: B and D only.
Solved Structural Organisation in Animals NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Are vocal sacs and copulatory pad seen in both male and female frogs?
No. Both are present ONLY in the male frog and are absent in the female. They are classic examples of sexual dimorphism in the frog.
Why does only the male frog have vocal sacs?
The male uses vocal sacs to produce a loud croaking sound to attract the female during the breeding season. The female does not need to call, so she has no vocal sacs.
Is the copulatory pad on the fore limb or hind limb?
On the FORE limb (front leg), on the FIRST digit. This is a very common NEET trap - never write hind limb.
What is amplexus?
Amplexus is the mating position where the male frog climbs onto the female's back and grips her using the copulatory pad on his fore limb, while eggs and sperms are released into water for external fertilisation.
