Oxygen: Life-Supporting Part of Air

• Know oxygen is an important component of air for breathing.
• Explain role of oxygen in burning and respiration at basic level.
• Observe oxygen use in daily activities and health settings.
• Appreciate plants and clean air spaces in Indian cities.

Level 1 - Air has many gases

Air is a mixture of gases. Oxygen is one key gas needed by humans and animals for breathing.

Level 2 - Oxygen and respiration

Our body uses oxygen to release energy from food. This is why we breathe faster during running or cricket practice.

Level 3 - Oxygen and burning

Combustion needs oxygen. A candle flame becomes weak and extinguishes if oxygen supply is reduced.

Level 4 - Indian context

In crowded traffic areas of Delhi, people feel better in parks with trees and fresher air. Hospitals provide oxygen support to patients with breathing difficulty. Tree plantation drives in schools help improve local air quality by balancing oxygen and carbon dioxide cycles.

NCERT anchor: Looking Around 4, Ch 21 — Food and Fun; Ch 26 — Defence Officer Wahida (breathing, activity, and health)

Candle under glass

Step 1 - Light a candle with adult supervision.
Step 2 - Cover it with a glass jar.
Step 3 - Observe flame becoming weak and going out.
Step 4 - Explain oxygen inside jar gets used.
Answer: Burning needs oxygen supply.

Breathing rate check

Step 1 - Count breaths in one minute at rest.
Step 2 - Do jumping for one minute.
Step 3 - Count breaths again.
Step 4 - Compare and explain increase in oxygen demand.
Answer: Physical activity raises oxygen requirement.

• Why do we breathe faster after running?
• What happened to candle under closed jar and why?
• Is oxygen the only gas in air?
• How can trees help air quality?
• Stretch: Make a poster linking breathing, oxygen, exercise, and planting trees in your locality.

Revision tip: Oxygen supports breathing and burning but is only one part of air.

Open the Practice tab for graded questions on Oxygen: Life-Supporting Part of Air.