Questions & Answers

Consider the following four statements (A - D) related to the common frog Rana tigrina, and select the correct option stating which ones are true (T) and which ones are false (F)?
(A) On dry land it would die due to lack of $O_2$.
(B) It has four-chambered heart
(C) On day land it turns uricotelic from ureotelic.
(D) Its life-history is carried out in pond water.
A. (A) - T, (B) - F, (C) - F, (D) - T
B. (A) - T. (B) - T. (C) - F, (D) - F
C. (A) - F, (B) - F, (C) - T, (0) - T
D. (A) - F, (B) - T, (C) - T, (D) - F

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Hint: Frogs belong to the class Amphibia. The main characteristics of the class Amphibia are moist and scaleless skin, cold-blooded animals, absorption water and gaseous exchange through the skin. Class Amphibia has three orders and frogs are the tailless amphibians belonging to the order Anura.

Complete answer:
The frogs absorb oxygen and release carbon dioxide. These animals acquire oxygen by breathing through their lungs, lining of their mouths and absorption through their skin.
Heart of a frog is three-chambered consisting of two atria and one ventricle.
Tadpoles are the young ones of a frog. They excrete nitrogenous wastes such as ammonia (ammonotelic), however adult frogs primarily excrete urea (ureotelic). So, frogs are not uricotelic.
Frogs are amphibians i.e. they live both on land and in water. Their primary habitat is in or near a pond or a lake where they complete their life cycle.

Hence, the correct answer is option (A)

Note: Frogs generally lay their eggs in water. These eggs hatch to reveal aquatic larvae known as tadpoles which have tails and internal gills. Frogs have very specific rasping mouthparts which are suitable for herbivorous, omnivorous or planktivorous foods. The life cycle of a frog is completed when they undergo metamorphosis and turn into adults.