What is photosynthesis?

• Photosynthesis is a chemical reaction that takes place in the chloroplasts of plant cells.

• During photosynthesis, plants use the energy of sunlight to produce energy-rich molecules called carbohydrates (ex. glucose).

In photosynthesis, plants take in carbon dioxide and water and release glucose and oxygen wastes.

8.2 What is photosynthesis?

• Chloroplasts are where photosynthesis occurs.

• Chloroplasts work much like solar cells found in calculators.

8.2 Light and color

• The Sun provides Earth with a steady source of light.

• Your eyes see sunlight as white light, but it is really made up of different colors of light.

A clear prism can split white light into a rainbow of color.

8.2 Light and color• Light is part of a collection of waves known as

the electromagnetic spectrum.• Waves can be described by their wavelength

(length from peak to peak), and their energy.

8.2 Light and color

• Color is how we experience the energy of light.

8.2 Chlorophyll

• A pigment is a molecule that absorbs some colors of light and reflects others.

• Chlorophyll is the main pigment used in photosynthesis.

8.2 Chlorophyll

• Chlorophyll absorbs mostly blue and red light, and reflects green light.

• This is why most plants look green.

8.2 Cellular respiration

• Cellular respiration is a chemical reaction that occurs in all living things.

• Cells use oxygen and glucose to produce carbon dioxide, water, and energy.

8.2 Cellular respiration• In most eukaryotic

organisms, cellular respiration takes place in the mitochondria of cells.

• During cellular respiration, energy is stored in a molecule called ATP while some energy is released as heat.

8.2 Comparing photosynthesis and respiration

• The chemical equations of photosynthesis and respiration have an interesting relationship.

• The reactants in photosynthesis are the products in cellular respiration!

• The reactants in cellular respiration are the products in photosynthesis!

Research Connection

• So how do stem cells change into other types of cells?

• Scientists are studying this problem.

Amazing Cells

Activity

• A concept map is a way to represent information visually.

• Create a concept map to explain how cells get and use energy.

Making a Concept Map