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Chapter 7 - Coggle Diagram
Chapter 7
The Light Reactions: Converting
Solar Energy to Chemical Energy
The distance between crests of electromagnetic waves is known as wavelength.
The electromagnetic spectrum is the full range of electromagnetic wavelengths from gamma rays to radio waves.
A photon has a certain amount of energy. The shorter the wavelength of light, the greater the energy of its photons.
A photosystem has two kinds of reaction complexes: 1) reaction center complex and 2) light-harvesting complex.
The chemiosmotic production of ATP is called photophosphorylation because the initial energy input is light (photo).
An Introduction to Photosynthesis
Photosynthesis is a process where plants use solar energy to convert carbon dioxide and water into sugar and other organic molecules and as a result releases oxygen gas.
To be an autotroph means that you can make your own food. Plants are autotrophs but are more specifically called photoautotrophs because plants use energy of light.
Controversially, to be a heterotroph means that you cannot create your own food. Therefore, in order to survive you must consume plants and/or animals.
Where and how does photosynthesis occur?
It occurs in the chloroplasts in plant cells. Chlorophyll is important in converting solar energy into chemical energy. (It is also the reason why leaves are green). Mesophyll is where the chloroplasts are concentrated in the cells. The way that CO2 enters and O2 exits is through tiny pores called stromata. In the chloroplast, a thick liquid called stroma holds together two membranous sacs called the thylakoids.
In photosynthesis, ATP and carbon dioxide goes is and NADPH and oxygen goes out.
Photosynthesis occurs in two stages linked by ATP and NADPH
1) Light Reaction: Occurs in the thylakoids. Converts light energy to chemical energy. This energy is used to drive the transfer of electrons and H+ to NADP+ (the electron acceptor). This results in NADP+ converting into NADPH.
2) Calvin Cycle: Occurs in the stroma. It assembles sugar molecules. The incorporation of carbon from CO2 into organic compounds is called carbon fixation.
The Calvin Cycle: Reducing
Carbon Dioxide to Sugar
C3 plants are plants where carbon fixation occurs and the first stable product of carbon fixation is a three-carbon intermediate compound.
Photorespiration occurs in the light (photo) and consumes O2 and releases CO2 (respiration).
C4 plants are plants where they first fix CO2 into a four-carbon compund.
CAM plants are adapted to very dry climates. They conserve water and only release CO2 at night.
The Global Significance of Photosynthesis
The greenhouse effect operates on a global scale. It is when solar radiation passes through the atmosphere and warms Earth's surface. Heat radiating from warmed planet is absorbed by greenhouse gases.
Climate change is a long-term change of the global climate that lasts for three decades or more.