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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

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

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

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

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

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

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

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

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

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

📐Formulae

C6H12O6+6O26CO2+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 DiffusionSurface 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.

Respiratory organs in animals - Revision Notes & Key Diagrams | CBSE Class 11 Biology