Learn: Photosynthesis

Welcome!Today we'll learn about photosynthesis, a process that is vital for plants to create their own food. We'll explore how it works, the conditions needed, and why it’s important for life on Earth.

What is Photosynthesis?Photosynthesis is the process by which plants use light energy from the sun to convert carbon dioxide and water into glucose (a sugar) and oxygen. This process happens in the chloroplasts of plant cells, which contain a green pigment called chlorophyll. It’s important because it provides food for plants and oxygen for other living organisms.

The Photosynthesis EquationThe word equation for photosynthesis is: carbon dioxide + water → glucose + oxygen. This reaction is powered by sunlight and occurs in the chloroplasts in the presence of chlorophyll.

Limiting Factors of PhotosynthesisPhotosynthesis can be affected by limiting factors, which are conditions that restrict the rate of the process. These include:Light intensity—More light generally increases the rate of photosynthesis.Carbon dioxide concentration—Plants need CO2 to make glucose.Temperature—Enzymes involved in photosynthesis work best within a certain range.

Leaf Structure and AdaptationsLeaves are specially adapted for photosynthesis:Large surface area—To absorb more sunlight.Thin—To allow gases like CO2 to diffuse quickly.Chloroplasts—Packed in the palisade layer for maximum light absorption.Stomata—Small openings that allow gas exchange.

Uses of GlucosePlants use the glucose produced in photosynthesis for:Respiration—To release energy.Storage—Converted into starch for later use.Growth—Used to make cellulose for cell walls and proteins.

Investigating PhotosynthesisOne way to investigate photosynthesis is by testing leaves for starch. This shows if photosynthesis has occurred as starch is made from glucose. Conditions like light and CO2 can be controlled in experiments.

Review Time!Great work! You've learned about photosynthesis, its equation, limiting factors, leaf adaptations, and the uses of glucose. Let’s review with a few more questions.