Photosynthesis

How do plants grow?

Like every other living organism, plants need energy to grow.

Plants do not eat food. So how do they get energy?

How do plants grow?

They produce their own energy through photosynthesis!

What is photosynthesis?

The prefix “photo-” means “light”

The suffix “-synthesis” means “putting together”

Photosynthesis is a process that captures energy from sunlight to make sugars that store chemical energy.

How does photosynthesis work?

Energy from sunlight is absorbed by a molecule called chlorophyll which is located in the chloroplast.

How does photosynthesis work?

Photosynthesis takes place in two stages: light dependent-reactions and light-independent reactions.

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Light-Dependent Reactions

During the light-dependent stage of photosynthesis, chlorophyll captures energy from sunlight.

Plants also take in H2O to use in these reactions.

Light-Dependent Reactions

A series of reactions occur where the sunlight energy is used to create energy-releasing molecules called NADPH and ATP.

These molecules will be used later.

Light-Dependent Reactions

Oxygen (O2) is given off as a waste product.

Light-Dependent Reactions

Net Reactants: Sunlight, H2O

Net Products: O2, NADPH, ATP

Light-Independent Reactions

Light independent reactions also take place in the chloroplast, but they do not need energy from sunlight. These reactions occur anytime that energy from NADPH and ATP is available.

Light-Independent Reactions

The light-independent reactions are a series of reactions that use carbon dioxide gas (CO2) and the energy from NADPH and ATP to make glucose (C6H12O6).

Light-Independent Reactions

Net Reactants: NADPH, ATP, CO2

Net Products: C6H12O6

Light-Independent Reactions - Big Picture

The product of the light-independent reactions is a 6-carbon sugar molecule.

What’s the Big Picture?

Now that we know the reactants and products of light-dependent and light-independent reactions, we can write a balanced equation for the entire process of photosynthesis.

What’s the Big Picture?

carbon dioxide + water ---light, enzymes---> sugar +

oxygen

OR

6CO2 + 6H2O ---light, enzymes---> C6H12O6 + 6O2

+ ----> +

6CO2 + 6H2O ---light, enzymes---> C6H12O6 + 6O2

What’s the Big Picture?

Photosynthesis requires water, sunlight, and carbon dioxide.

What’s the Big Picture?

Plants remove carbon dioxide from the atmosphere and release oxygen.

What’s the Big Picture?

Photosynthesis produces energy for plants by making glucose.

Animals eat plants to gain energy from the glucose made in photosynthesis.

Animals also eat other animals that eat plants.

Therefore, photosynthesis provides energy for the entire food chain.