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Breathing and Exchange of Gases - Respiratory organs in animals

Grade 11CBSEBiology

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

🔑Concepts

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Respiration is the process of exchange of O2O_2 from the atmosphere with CO2CO_2 produced by the cells, often referred to as breathing.

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The mechanism of breathing varies among different groups of animals depending mainly on their habitats and levels of organisation.

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Lower invertebrates like sponges, coelenterates, and flatworms exchange O2O_2 with CO2CO_2 by simple diffusion over their entire body surface.

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Earthworms use their moist cuticle (cutaneouscutaneous respiration) for the exchange of gases.

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Insects have a network of tubes called tracheal tubes to transport atmospheric air within the body.

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Special vascularised structures called gills (branchialbranchial respiration) are used by most of the aquatic arthropods and molluscs.

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Vascularised bags called lungs (pulmonarypulmonary respiration) are used by the terrestrial forms for the exchange of gases.

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Among vertebrates, fishes use gills whereas reptiles, birds, and mammals respire through lungs.

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Amphibians like frogs can respire through their moist skin (cutaneouscutaneous respiration) as well as lungs.

📐Formulae

C6H12O6+6O2→6CO2+6H2O+Energy(ATP)C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + Energy (ATP) syntax for aerobic respiration

Pgas=Total Pressure×Mole Fraction of gasP_{gas} = \text{Total Pressure} \times \text{Mole Fraction of gas}

Rate of Diffusion∝Surface Area×ΔPThickness of Membrane\text{Rate of Diffusion} \propto \frac{\text{Surface Area} \times \Delta P}{\text{Thickness of Membrane}}

💡Examples

Problem 1:

Identify the respiratory organs in the following animals: (i) Prawn (ii) Cockroach (iii) Frog (iv) Earthworm.

Solution:

(i) Gills (ii) Tracheal tubes (iii) Lungs and Moist Skin (iv) Moist Cuticle

Explanation:

Prawns are aquatic arthropods and use gills. Cockroaches utilize a tracheal system. Frogs are amphibians capable of both pulmonary and cutaneous respiration. Earthworms perform gas exchange through their skin surface.

Problem 2:

Why do mammals have a more complex respiratory system (lungs) compared to sponges?

Solution:

Mammals have high metabolic demands and a large body volume-to-surface area ratio, requiring efficient pulmonarypulmonary respiration.

Explanation:

In sponges, the body organization is simple (cellular level), and most cells are in direct contact with water, allowing simple diffusion. Mammals require specialized vascularized lungs to transport O2O_2 to deep-seated tissues.