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Breathing and Exchange of Gases

ICSE · Class 11 · Biology

Quick revision notes for Breathing and Exchange of Gases — ICSE Class 11 Biology. Key concepts, formulas, and definitions for last-minute revision.

60 questions40 flashcards5 concepts

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An infographic comparing different types of respiratory organs found in various animals, such as moist cuticle (earthworm), gills (fish, aquatic arthropods, molluscs), tracheal tubes (insects), and lu
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Key Topics to Revise

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1. Respiratory organs in animals

  • Respiratory organs are the organs concerned with gaseous exchange, that is, intake of oxygen and output of carbon dioxide.
  • In unicellular organisms such as Amoeba, gaseous exchange occurs through the general body surface or plasmalemma.
  • In Sycon and Hydra, gas exchange takes place by simple diffusion between flowing water and individual cells.
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2. Human respiratory system

  • The human respiratory system has two main components: the lungs and the respiratory tract.
  • The respiratory tract includes nostrils, nasal cavity, nasopharynx, larynx, trachea, bronchi, and bronchioles.
  • Nostrils are the openings of the nasal cavities.
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3. Mechanism of breathing and gas exchange

  • Breathing is the mechanical process of taking fresh air into the lungs and expelling foul air from the lungs.
  • Inspiration is active and expiration is passive.
  • Breathing is involuntary and normally occurs at a constant rate of 12 to 14 per minute in a resting person.
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4. Transport of oxygen and carbon dioxide

  • About 97 per cent of oxygen is transported by RBCs and about 3 per cent is carried dissolved in plasma.
  • In arterial blood, about 19 mL of oxygen is present per 100 mL blood; 0.3 mL is dissolved in plasma and 18.7 mL is bound to haemoglobin.
  • Haemoglobin is an iron-containing respiratory pigment in RBCs.

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Full Notes

Key Concepts

Respiration is the process byRespiratory organs are structures concernedAmoebaEarthworms and leeches exchange gases throughInsects respire through a network

Frequently Asked Questions

What are the important topics in Breathing and Exchange of Gases for ICSE Class 11 Biology?
Breathing and Exchange of Gases covers several key topics that are frequently asked in ICSE Class 11 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Breathing and Exchange of Gases — ICSE Class 11 Biology?
Understand the core concepts first, then work through the 60 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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