Photosynthesis

Understanding the process that powers plant life and sustains the Earth

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What is Photosynthesis?

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, usually from the Sun, into chemical energy stored in glucose. This process occurs mainly in the leaves of plants within structures called chloroplasts.

it was created by AINEBYOONA MATHIUS and AINEMBABAZI HILLARY

Diagram of Photosynthesis Process (Image via Pixabay CDN)

Photosynthesis Equation

The overall equation for photosynthesis is:

6CO2 + 6H2O + sunlight ? C6H12O6 + 6O2

• CO2 (Carbon Dioxide) is absorbed from the air through stomata.
• H2O (Water) is absorbed by roots from the soil.
• Sunlight provides energy for the reaction.
• Glucose is used for energy or stored as starch.
• Oxygen is released as a by-product.

Importance of Photosynthesis

Photosynthesis is crucial for life on Earth as it:

• Provides food for plants and indirectly for all animals.
• Releases oxygen necessary for respiration.
• Removes carbon dioxide from the atmosphere.

4. Inner Processes: Light-dependent vs Light-independent Reactions

Photosynthesis has two main phases that work together to create food for the plant. Here's how each stage works:

Overview of the Two Stages of Photosynthesis (Wikimedia)

5. The Role of ATP and NADPH

During the light-dependent reactions, two key molecules are created: ATP and NADPH.

• ATP (Adenosine Triphosphate): Acts as an energy currency that powers the Calvin Cycle.
• NADPH: Carries high-energy electrons needed to convert CO2 into glucose.

How ATP and NADPH are used in the Calvin Cycle (Wikimedia)

Fun Fact: Plants make enough ATP in a single leaf to power a small LED light!

Deep Dive into Photosynthesis

1. The Chloroplast ? The Photosynthesis Factory

Photosynthesis occurs in the chloroplasts of plant cells. These organelles contain a green pigment called chlorophyll that captures sunlight. A single leaf may contain millions of chloroplasts!

Structure of a Chloroplast (Wikimedia CDN)

2. Stages of Photosynthesis

Photosynthesis is a two-stage process:

• Light-dependent Reactions: Occur in the thylakoid membranes and require sunlight. Water is split (photolysis), releasing oxygen and transferring energy to ATP and NADPH.
• Light-independent Reactions (Calvin Cycle): Occur in the stroma of the chloroplast. These reactions use ATP and NADPH to convert carbon dioxide into glucose.

3. Factors Affecting Photosynthesis

The rate of photosynthesis is influenced by several environmental factors:

• Light Intensity: More light generally increases the rate until a saturation point.
• Carbon Dioxide Concentration: Higher CO2 means more raw material for glucose production.
• Temperature: Affects the enzymes involved. Too hot or too cold can slow or stop the process.
• Water Availability: Water is essential for photolysis. A shortage can halt photosynthesis.