Prentice Hall - Science Explorer - Cells and Heredity
Chapter 2- Cell Processes and Energy
Section 1- Photosynthesis
Questions - Comment -
Key Words - Connections
Photosynthesis
Autotroph
Heterotroph
Pigment
Chlorophyll
Stomata
Main Ideas; Visuals + Predictions
Sources of Energy
Photosynthesis: The process by which plants and some other organisms capture the energy in sunlight and use it to make food.
* Nearly all living things obtain energy either directly or indirectly from the energy of sunlight captured during photosynthesis.
Ex: Grass gets energy directly from sunlight then, the zebra eats the grass getting its stored energy. After, the lion eats the zebra getting its stored energy too. Both the Zebra and Lion gets its energy from sunlight indirectly, from the energy the grass obtained during photosynthesis.
Autotroph:An organism that makes its own food. ex: plants
Heterotroph:An organism that cannot make its own food. ex: Lions, Zebras and Humans
The Two Stages of Photosynthesis
* During photosynthesis, plants and some other organisms use energy from the sun to convert carbon dioxide and water into oxygen and sugars. * Photosynthesis takes two stages
Capturing the sun's energy
Producing Sugars
ex: like a recipe it must be in the correct order to have the wanted result.
Stage 1: Capturing the Sun's Energy Pigment: A colored chemical compound that absorbs light.
Chlorophyll: A green pigment found in the chloroplasts of plants, algae, and some bacteria.
* chlorophyll captures light energy and uses it to power the second stage of photosynthesis.
ex: a solar cell which powers a calculator.
Stage 2: Using Energy to Make Food * The cell uses the captured energy to produce sugars. The cell needs two raw materials for this stage: water (H2O) and carbon dioxide (CO2).
Stomata: Small openings on the underside of a leaf through which oxygen and carbon dioxide can move.
* Inside the chloroplasts, the water and carbon dioxide undergo a complex series of chemical reactions and makes one product of sugar (C6H12O6) with 6 carbon atoms. * The energy from the sugar is used to carry out important functions within the cell. * The other product of photosynthesis is oxygen (O2), which exits the leaf through the stomata.
PhotosynthesisEquation
* The arrow means yield meaning produce or provide.