8.1 and 8.2

Energy The ability to do work. Different forms Mechanical Thermal Chemical light

Thermodynamics Study of the flow of transfer of energy in the universe. 2 laws Energy cannot be created or destroyed When energy is converted to different forms, there is a loss of usable energy. “Entropy Increases”

Autotrophs and Heterotrophs Autotrophs make their own food. Heterotrophs get food from autotrophs or other heterotrophs.

How do organisms obtain energy? Process of Metabolism -> all the chemical reactions in the cell = cell’s metabolism Photosynthesis -> light energy to chemical energy Cellular respiration-> molecules broken down to release energy

2 Metabolic Pathways Anabolic -> use energy to build larger molecules from smaller molecules. Catabolic-> Releases energy through breakdown of molecules

Adenosine Triphosphate Most important biologic molecule that provides energy. Energy is stored between 2nd and 3rd phosphate bond. When that bond is broken energy is released.

Basic Anatomy of a Plant

LEAVES Usually contain chlorophyll and other pigments Other pigments: xanthnophyll, carotene Flat (collects sunlight better) Several layers Cuticle Mesophyll (spongy and palisade) Epidermis

Stomata CO2 enters and O2 Leaves

Photosynthesis Know this! It will be on your test

Photosynthesis Occurs in 2 Phases Phase One: Light -Dependent Reaction Phase Two: Light- Independent Reaction or Calvin Cycle

Chloroplast captures light energy.

The Process Light energy excites electrons in photosystem II and also causes a water molecule to split, releasing an electron into the electron transport system, H+ into the thylakoid space, and O2 as a waste product

The Process The excited electrons move from photosystem II to an electron-acceptor molecule in the thylakoid. The electron-acceptor molecule transfers the electrons along a series of electron-carriers to photosystem I

The Process Photosystem I transfers the electrons to a protein called ferrodoxin. Ferrodoxin transfers the electrons to the electron carrier NADP+, forming the energy-storing molecule NADPH.

Chemiosmosis ATP is produced by the flow of electrons down the concentration gradient. H+ that is released when H2O is split helps drive chemiosmosis. H+ diffuses through ion channels and ATP is formed.

Phase 2: The Calvin Cycle or light- independent reactions.

Calvin Cycle Energy is stored in organic molecules like glucose

Six CO2 molecules combine with six 5-carbon compounds to form twelve 3-carbon molecules called 3-PGA. The chemical energy stored in ATP and NADPH is transferred to the 3-PGA molecules to form high-energy molecules called G3P.

Two G3P molecules leave the cycle to be used for the production of glucose and other organic compounds. An enzyme called rubisco converts the remaining ten G3P molecules into 5-carbon molecules called RuBP These molecules combine with new carbon dioxide molecules to continue the cycle.

Alternative Pathways C4 Plants- Corn and Sugarcane Fix CO2 in to 4- carbon molecules instead of 3- carbon molecules during Calvin Cycle. Close stomata prevent water loss -> 4- carbon molecule used during day so plant has plenty of CO2

Alternative Pathways CAM plants- crassulacean acid metabolism Plants in desert and salt marshes. Ex: cacti, orchids, and pineapples Take in and Fix CO2 at night