PHOTOSYNTHESIS INTRODUCTION All cells need energy All cells

PHOTOSYNTHESIS

INTRODUCTION • All cells need energy. All cells get their energy in the form of chemical energy. • Chemical energy is the energy stored in the bonds between atoms of every molecule. • Cells must be able to release energy stored in the bonds of their food molecules.

INTRODUCTION • The molecule used by most organisms as an energy source is glucose. • Plants make their own glucose, while animals must consume food in order to obtain glucose.

PHOTOSYNTHESIS • The source of energy for most organisms ultimately comes from the sun. • During the process of photosynthesis, plants change the energy from the sun to the chemical energy (energy they can use) stored in the bonds of glucose molecules.

LOCATION • Photosynthesis takes place in plant cells that contain chloroplasts, i. e. leaves. • Chloroplasts contain chlorophyll, a lightabsorbing pigment, that traps the energy in sunlight.

A CHEMICAL CHANGE Reactants • Carbon dioxide (CO 2) from the air • Water (H 2 O) from the soil

A CHEMICAL CHANGE Chemical Reaction • The energy in the chlorophyll (sunlight) causes the atoms in carbon dioxide and the water to recombine and become new substances

A CHEMICAL CHANGE Products • Glucose (sugar) – plants keeps for its energy needs • Oxygen (O 2) – released in to the air

A CHEMICAL CHANGE Water + Carbon dioxide + Light energy Glucose + Oxygen

PHOTOSYNTHESIS GLUCOSE CARBON DIOXIDE CHLOROPLAST LIGHT ENERGY OXYGEN WATER