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Structural Organisation in Animals - Morphology, Anatomy and functions of Frog

Grade 11CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Taxonomy: The common Indian bullfrog is scientifically known as Rana tigrinaRana \ tigrina. It belongs to the class Amphibia and phylum Chordata.

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Morphology: The body is divided into head and trunk. Neck and tail are absent. The skin is moist, smooth, and slippery due to mucus glands, which aids in cutaneous respiration (O2O_2 and CO2CO_2 exchange).

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Sexual Dimorphism: Male frogs are distinguished by the presence of sound-producing vocal sacs and a copulatory pad on the first digit of the forelimbs, which are absent in females.

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Digestive System: Frogs are carnivores, so the alimentary canal is short. Digestion involves HClHCl and gastric juices secreted from the stomach wall. Chyme is passed into the duodenum where it receives bile and pancreatic juice.

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Respiration: Frogs exhibit three types of respiration: Cutaneous (through skin in water/hibernation), Buccal (mouth cavity), and Pulmonary (lungs on land).

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Circulatory System: They possess a closed circulatory system with a 33-chambered heart (22 atria and 11 ventricle). They have unique portal systems: Hepatic portal (between liver and intestine) and Renal portal (between kidney and lower body).

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Excretory System: Frogs are ureotelic, excreting urea (NH2CONH2NH_2CONH_2). The system consists of a pair of kidneys, ureters, cloaca, and a urinary bladder.

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Nervous System: The central nervous system consists of the brain and spinal cord. There are 1010 pairs of cranial nerves arising from the brain.

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Male Reproductive System: Consists of a pair of yellowish ovoid testes. Sperm enters the kidneys via 10−1210-12 vasa efferentia and passes through Bidder's canal to the urinogenital duct.

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Female Reproductive System: Consists of a pair of ovaries situated near kidneys (no functional connection). A female lays 25002500 to 30003000 eggs at a time. Fertilization is external and occurs in water.

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Development: Includes a larval stage called a tadpole, which undergoes metamorphosis to become an adult.

📐Formulae

Heart Chambers=2 Atria+1 Ventricle\text{Heart Chambers} = 2 \text{ Atria} + 1 \text{ Ventricle}

Cranial Nerves=10 Pairs\text{Cranial Nerves} = 10 \text{ Pairs}

Excretory Product=NH2CONH2 (Urea)\text{Excretory Product} = NH_2CONH_2 \text{ (Urea)}

Body Division=Head+Trunk\text{Body Division} = \text{Head} + \text{Trunk}

💡Examples

Problem 1:

Describe the pathway of sperm in a male frog starting from the testes.

Solution:

Testes →\rightarrow Vasa efferentia (10−1210-12 in number) →\rightarrow Bidder's canal →\rightarrow Urinogenital duct →\rightarrow Cloaca.

Explanation:

In male frogs, the 10−1210-12 vasa efferentia arise from the testes and enter the kidneys to open into Bidder's canal, which then communicates with the urinogenital duct.

Problem 2:

How does the frog maintain body temperature despite environmental changes?

Solution:

Frogs are poikilotherms (cold-blooded).

Explanation:

Frogs do not have a constant body temperature; their body temperature varies with the temperature of the environment. To survive extreme heat or cold, they perform aestivation (summer sleep) and hibernation (winter sleep) respectively.

Problem 3:

Identify the respiratory organs used by a frog during hibernation.

Solution:

The skin (Cutaneous respiration).

Explanation:

During hibernation and aestivation, gaseous exchange takes place strictly through the skin, as the metabolic rate is significantly reduced and the frog remains inactive.

Morphology, Anatomy and functions of Frog Revision - Class 11 Biology CBSE