16 public questions tagged with this topic.
Fat bodies in frogs store energy, which is used during hibernation and breeding seasons.
Ref: NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals Frog - Anatomy - Nervous System Sense Organs and Reproductive System
The nictitating membrane covers the frog’s eyes while in water, providing protection.
Ref: NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals Frog - Anatomy - Nervous System Sense Organs and Reproductive System
The stomach does not open directly into the cloaca; food passes through the intestine for digestion and absorption.
Ref: NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals Frog - Anatomy - Digestive and Respiratory System
The intestine in frogs is relatively short because they are carnivorous, unlike herbivores that require longer intestines for plant digestion.
Ref: NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals Frog - Anatomy - Digestive and Respiratory System
Frog skin is moist and glandular, allowing respiration through cutaneous gas exchange.
Ref: NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals Frog - Morphology and External Features
The notochord is a flexible rod-like structure that supports the body in chordates during early development (NCERT, Chapter 4, page 55). The vertebral column replaces it in vertebrates, the spinal cord is the nerve cord, and the hemocoel is in arthropods.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Hemichordata and Chordata - Protochordata
Molluscan shell is external calcareous exoskeleton secreted by specialized epithelium of mantle, particularly outer fold and periostracal groove. Mantle edge contains shell glands sequentially depositing organic periostracum of conchiolin, middle prismatic calcite columns, inner nacreous aragonite tablets. Outer epithelium actively transports calcium from hemolymph and seawater into extrapallial fluid where crystallization controlled by matrix proteins. Growth occurs by marginal accretion allowing concentric expansion, while inner mantle deposits nacre for thickening and pearl formation. Foot provides locomotion, radula rasping feeding, visceral mass houses organs, not shell secretion mechanism in any mollusc class.
Ref: NCERT Class 11 Biology, Chapter 4: Mollusca mantle function; Campbell Biology, Chapter 33
Jawless fishes retain ancestral craniate morphology lacking innovations of gnathostomes. Most conspicuously they lack paired pectoral and pelvic fins that provide stabilization, braking and maneuvering in cartilaginous and bony fishes. Instead, locomotion depends on median dorsal and caudal fins plus body undulation creating anguilliform waves. Additional primitive characters include absence of true scales in hagfishes, cartilaginous cranium, single nostril and persistence of notochord. Gill basket supports branchial structures. Absence of paired fins reflects evolutionary stage predating appendage duplication and fin module development via Tbx genes, distinguishing Agnatha from Gnathostomata.
Ref: NCERT Class 11 Biology, Chapter 4: Cyclostomata; Brusca & Brusca, Chapter 24, Agnatha Paired Fins
Condition possessing two separate external nostrils or nares connected via internal choanae to buccal cavity is termed dirhinous derived from Greek di two and rhinos nose, representing standard gnathostome vertebrate arrangement including fishes, amphibians, reptiles, birds and mammals where paired olfactory sacs sample water or air bilaterally improving gradient detection. Monorhinous or monorhiny describes single median nostril in cyclostomes lamprey and hagfish, trirhinous hypothetical anomaly, polyrhinous multiple irregular openings pathological not evolutionary term. Dirhiny facilitates bilateral olfaction and respiratory flushing through nasal passages.
Ref: Romer Vertebrate Body 6th ed. Nasal Terminology; Campbell Biology 12th ed. Chapter 34 Olfactory Evolution
Amphibians possess both hepatic and renal portal systems. Hepatic portal collects deoxygenated nutrient-rich blood from stomach, intestine, spleen via hepatic portal vein into hepatic sinusoids for detoxification, glycogen storage and plasma protein synthesis before returning to sinus venosus via hepatic veins. Renal portal connects veins from hindlimbs and pelvis to kidney peritubular capillaries enabling tubular secretion and reabsorption before caval return, aiding nitrogenous waste handling. Both present well developed not absent, double circulation separate phenomenon, illustrates ectothermic low-pressure pattern with portal routes.
Ref: Romer Vertebrate Body Portal Systems; NCERT Class 11 Chapter 18 Portal Circulation Amphibians
Erythrocytes of amphibians characteristically large, oval to elliptical, nucleated retaining central nucleus capable of transcription throughout lifespan, containing hemoglobin within cytoplasm, size up to 20-70 micrometres exceeding mammalian cells dramatically, reflecting large genome including 20-120 picogram DNA content in salamanders. Oval nucleated shape reduces surface to volume but sufficient for low metabolic rate and continuous erythropoiesis in bone marrow and spleen. Enucleated biconcave discs optimize deformability and hemoglobin packing in mammals only, spindle shaped not typical amphibian trait. This concept holds high importance for NEET, CBSE board, CUET and competitive examinations focusing on comparative morphology
Ref: Campbell Biology 12th ed. Chapter 42 Vertebrate Blood Cells; NCERT Class 11 Biology Chapter 18 RBC Morphology
Amphibian heart three-chambered architecture comprises two separate atria left atrium receiving oxygenated blood from pulmonary veins and cutaneous veins, right atrium receiving deoxygenated systemic venous blood via sinus venosus, and single undivided ventricle with trabeculae carneae and spiral valve within conus arteriosus partially directing streams reducing mixing. Systemic and pulmocutaneous circuits partially overlapping, less efficient than four-chambered avian mammalian. Sinus venosus and truncus arteriosus prominent embryonic remnants persisting, reflecting transition between two-chambered fish heart and fully septated amniote heart. This concept holds high importance for NEET, CBSE board, CUET and competitive examinations focusing on comparative
Ref: NCERT Class 11 Chapter 18 Amphibian Circulatory System; Campbell Biology 12th ed. Chapter 42 Heart Evolution
