Q1.
Have you ever wondered how the food you eat gives you energy?
Answer
The key is not only the food but also the oxygen we breathe. Food alone cannot give energy, and oxygen alone has nothing to act on — the two must meet inside the body.
- Food is digested and broken down into simple substances like sugar (glucose).
- The glucose is absorbed into the blood and carried to every part of the body.
- Oxygen from the inhaled air passes from the alveoli into the blood and is also carried everywhere.
- Oxygen helps break down the glucose, and energy is released. This is respiration.
- Carbon dioxide and water are formed as waste; the blood carries the carbon dioxide back to the alveoli, and we breathe it out.
Glucose + Oxygen → Carbon dioxide + Water + Energy
Why it happens: the energy is locked inside the glucose molecule. Oxygen is what unlocks it. This is why you feel breathless after running — your muscles want more energy, so they want more glucose broken down, so they want more oxygen, so you breathe faster.
Did you know? This is the same energy that lets you walk, run, play — and even think. The brain uses a large share of the body's energy while sitting perfectly still.