Biology · Animal Kingdom · NEET
Most reptiles have a 3-chambered heart (2 atria + 1 ventricle). The key NEET exception is the crocodile, which has a 4-chambered heart. So the safe statement is 'usually 3-chambered, but 4-chambered in crocodiles.' NEET loves the trap 'ALL reptiles have a 3-chambered heart' — this is FALSE because of the crocodile.
NCERT only states the fact: heart is usually three-chambered but four-chambered in crocodiles. You do NOT need a reason for NEET — just remember crocodile is the odd one out. This single exception is enough to make any 'all reptiles' statement wrong in an exam.
Reptiles are poikilotherms, meaning cold-blooded. Their body temperature changes with the surroundings; they cannot keep a constant body temperature. NEET 2026 marked the statement 'Members of class Reptilia maintain a constant body temperature' as INCORRECT for this exact reason. Only birds (Aves) and mammals are homeotherms (warm-blooded).
The name comes from the Latin words repere or reptum, meaning 'to creep or crawl.' It refers to their creeping/crawling mode of locomotion. This is a correct, testable NCERT statement — ReNEET 2026 confirmed Statement I 'Reptilia refers to creeping/crawling locomotion' is correct.
No. Reptiles do NOT have external ear openings. Instead, the tympanum (ear drum) represents the ear. This is a common NEET one-liner used to separate reptiles from mammals, which do have external ears.
Reptiles are oviparous (egg-laying) and their development is DIRECT — there is no larval stage and no metamorphosis, unlike amphibians. Sexes are separate and fertilisation is internal. Snakes and lizards shed their scales as a skin cast.
Reptile skin is dry and cornified, covered by epidermal scales or scutes made of keratin — this prevents water loss and suits land life. Fish scales are dermal and bony, and fish skin stays moist. Dry scaly skin is a key adaptation that let reptiles become fully terrestrial.
Statement I: The class name Reptilia refers to creeping or crawling mode of locomotion. Statement II: All organisms belonging to Reptilia have a three-chambered heart. Choose the most appropriate answer:
Select the incorrect statements: A. Digestive system in Platyhelminthes is incomplete. B. Bilateral symmetry is a characteristic feature of adult Echinoderms. C. Pseudocoelom is possessed by Aschelminthes. D. Notochord is persistent throughout life in Chondrichthyes. E. Members of class Reptilia maintain a constant body temperature.
Which one of these animals is not a homeotherm?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Creeping/crawling locomotion; mostly terrestrial; dry cornified skin with epidermal scales or scutes; no external ear (tympanum present); two pairs of limbs when present; heart usually 3-chambered (4 in crocodiles); poikilothermic; separate sexes; internal fertilisation; oviparous with direct development.
The crocodile. All other common reptiles (turtles, tortoises, lizards, snakes) have a 3-chambered heart. This is the single most tested exception in NEET reptile questions.
Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Crocodilus (Crocodile), Alligator, Hemidactylus (Wall lizard), and poisonous snakes Naja (Cobra), Bangarus (Krait), Vipera (Viper).
Their dry cornified scaly skin prevents water loss, internal fertilisation removes the need for water to reproduce, and they lay shelled eggs on land (oviparous) with direct development. Amphibians still depend on water; reptiles do not, so they are the first fully terrestrial vertebrates.
Yes. NCERT states that snakes and lizards shed their scales as a skin cast. This periodic shedding of the outer scaly layer is a recognised reptilian feature.
