Question

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
Choose the correct answer from the options given below:

• A. B and D only
• B. B and C only
• C. A and B only
• D. C and E only

Hint:

Logic Tip: In frogs, male-specific features are entirely tied to reproduction: making noise to call the female (vocal sacs) and holding onto her tightly once she arrives (copulatory pads).

Answer 1

The Correct Option is A

Step 1 : Understanding the Question:
This question asks about sexual dimorphism in frogs ({Rana tigrina}). We must identify which of the listed morphological features are found {only} in male frogs and are absent in females.
Step 2 : Key Formulas and Approach:
Identify the secondary sexual characters in frogs. These are usually traits that aid in attracting a mate or maintaining a grip during the mating process (amplexus). General adaptive traits for camouflage or vision are usually shared by both sexes.
Step 3 : Detailed Explanation:

Vocal Sacs (B): These are loose folds of skin under the mouth of male frogs. They act as resonating chambers to amplify the croaking sounds during the breeding season to attract females. Females lack vocal sacs.

Copulatory Pads (D): These are specialized swellings (also called nuptial pads) found on the first digit of the forelimbs in male frogs. They help the male to firmly hold the female during amplexus. Females lack these pads.

Shared Traits (A, C, E):
Bulging eyes with nictitating membranes are present in both sexes for vision and protection.

Webbed digits on the feet are swimming adaptations common to both sexes.

Olive green skin with spots is a camouflage adaptation for survival, present in both males and females.


Step 4 : Final Answer:
Since only the vocal sacs and the copulatory pads are unique to the males, statements B and D are the distinguishing features. This corresponds to option (A).