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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 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