What gas do living creatures need to breathe?

 Living creatures, especially animals and humans, need to breathe oxygen.

Here's why:

Oxygen is a gas found in the air that is essential for survival. It plays a key role in a process called cellular respiration, which happens in the cells of most living organisms.

What is cellular respiration?

It's the process by which cells use oxygen to break down glucose (sugar) and release energy. This energy is used for all the activities that keep a living organism alive—like moving, growing, thinking, and maintaining body temperature.

Where do we get oxygen?

• Humans and animals breathe in oxygen from the air through their lungs (or gills in fish).
• The oxygen travels through the blood to the cells of the body.
• Inside the cells, oxygen helps release energy from food.
• As a byproduct, the cells produce carbon dioxide (CO₂), which is then breathed out.

Why is oxygen important?

• Without oxygen, our cells can't produce the energy they need to function.
• The brain is especially sensitive to a lack of oxygen and can be damaged in just a few minutes without it.

Bonus Fact:

• Plants also need oxygen for their own cellular respiration, especially at night when they are not photosynthesizing.
• But during the day, plants produce more oxygen than they use, which helps keep the air full of the oxygen that animals and humans need.

Summary:

Living creatures need oxygen to breathe because it allows their cells to make energy from food. Without oxygen, life for most animals, including humans, would not be possible.