5.3 OXYGEN IS NEEDED FOR

RESPIRATIONLEARNING OUTCOMES:State that energy, water vapour and

carbon dioxide are the products of respiration

Relate that living things use oxygen and give out carbon dioxide during respiration

compare and contrast the content of oxygen in inhaled and exhaled air

INTRODUCTIONAll living things need food to survive

Food provide us with energyWe need energy for all activities carried out by the body and for all life processes (example growth and reproduction)

RESPIRATIONRESPIRATION is a process where our

body obtain energy from food that we eat

Respiration occurs in the cells of human body

During respiration, food in the form of sugar is oxidised by the oxygen.

The products of respiration ◦energy, ◦carbon dioxide and ◦water vapour

RESPIRATION IN CELLS

ANIMAL CELL

Oxygen

Food (Sugar) Water Vapour

Carbon Dioxide

Energy

Oxygen

Food (Sugar) Water

Vapour

Carbon Dioxide

Energy

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+

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RESPIRATION

Product of respiration

Composition of Inhaled and Exhaled Air

Living things obtain the oxygen needed for respiration through breathing.

During breathing, living things take in oxygen from the air to produce energy and remove carbon dioxide and water vapour.

Thus, the percentage of oxygen gas is higher in inhaled air, compared to exhaled air

Composition of Inhaled and Exhaled Air

In contrast, the percentage of carbon dioxide gas in lower in inhaled air compared to exhaled air.

The percentage of Nitrogen and Inert gases remain the same in inhaled and exhaled air.

This is because both Nitrogen and Inert gases does not involve in respiration

Composition of Inhaled and Exhaled Air

Exhaled air contains more water vapour than inhaled air because water vapour is released as one of the respiration product

The temperature of exhaled air is higher that the inhaled air as the exhaled air is similar to the body temperature (37°C)

Varies

REFLECTIONS

5.3 Oxygen is needed

for respiration

What is cell respiration process?

RESPIRATION is a process where our body obtain energy from food that we eat through oxidation.

Give the three products of respiration.

1. Carbon Dioxide

2. Water vapour3. Energy

Write out the equation for respiration process

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Compare the composition of inhaled and exhaled air in the table below

Inhaled Air Composition Exhaled Air

Oxygen

Carbon dioxide

Water vapour

Nitrogen

Inert gases

heat