Carbohydrates are formed through a process called photosynthesis. This is a complex series of reactions that occur in plants and some bacteria. Here's a simplified overview:

Inputs:

* Carbon dioxide (CO2): Taken from the atmosphere

* Water (H2O): Absorbed from the soil through roots

* Sunlight: Provides the energy to drive the reaction

Output:

* Glucose (C6H12O6): A simple sugar that is the basic building block of carbohydrates

* Oxygen (O2): Released into the atmosphere

The overall chemical reaction can be summarized as:

6CO2 + 6H2O + sunlight → C6H12O6 + 6O2

Here's a breakdown of what happens:

1. Light-dependent reactions: Sunlight energy is captured by chlorophyll (a green pigment) in chloroplasts (organelles within plant cells). This energy is used to split water molecules, releasing oxygen and creating high-energy molecules called ATP and NADPH.

2. Light-independent reactions (Calvin cycle): Carbon dioxide from the atmosphere is combined with the energy stored in ATP and NADPH to create glucose.

This process is essential for life on Earth, as it provides the energy source and building blocks for most organisms.