Composition of Air and Respiration

Composition of Air

• Air is composed of 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, and 0.9% noble gases.
• Water vapor and other gases are also present in varying amounts.

Testing for Gases

• Oxygen: Supports burning; relights a glowing splint.
• Carbon Dioxide: Supports burning, denser than air; turns a red-yellow litmus indicator to yellow, turns limewater from clear to milky.

Breathing Mechanism

• Breathing involves gas exchange in the lungs:
  • Inhaled air enters the blood in capillaries.
  • Carbon dioxide is removed from the blood and exhaled.
  • Oxygen is absorbed by the blood and transported to the body.

Respiration

• Respiration is the process of breaking down glucose (food) to release energy.
  • Oxygen is needed and carbon dioxide is produced.
• Respiration in cells involves controlled chemical reactions inside cells. Stored chemical energy in glucose is released.

Photosynthesis

• Plants use sunlight to convert carbon dioxide and water into glucose (food) and release oxygen.
  • The process occurs in the presence of chlorophyll and involves chemical reactions within the plant cells.
• Photosynthesis and respiration balance the carbon dioxide and oxygen levels in the environment.

Effect of Pollutants

• Exposure to pollutants like sulphur dioxide, nitrogen oxides, ozone, carbon monoxide, and suspended particulates can cause irritation to the eyes, headache, breathing problems, and other health risks.
• Air pollutants disrupt the balance in the atmosphere. The effects are a noticeable and harmful impact.
• AQHI (Air Quality Health Index) tells the public about possible risks from air pollutants and suggests precautions.