Photosynthesis Unit

Energy Flow through an Ecosystem

Photosynthesis = a process that captures energy from sunlight to make sugars that store chemical energy

Photosynthesis (cont) - plants absorb visible light for photosynthesis - appears white but is made of a variety of colors (ROYGBIV) = visible spectrum

Photosynthesis (cont) - pigment = a compound that absorbs light - different colors absorb different colors of light

Photosynthesis (cont) - chlorophyll = a molecule in chloroplasts that absorbs visible light - two types: chlorophyll a (primary pigment) chlorophyll b (accessory pigment) - absorb mostly red and blue light - neither a nor b absorbs green light (this is why plants appear green – color is reflected)

Structure of Chlorophyll a and Chlorophyll b

Photosynthesis (cont) - carotenoids (accessory pigments) – contain yellow, orange, red, brown pigments - in plants, chlorophylls are much more abundant than other pigments - in fall, plants lose their chlorophylls (carotenoids then become visible)

1) Chloroplast 2) Sunlight 3) Water (H 2 0) 4) Thylakoid contains: chlorophyll contains: chlorophyll 5) Oxygen 6) Energy transferred to Dark Reactions 7) Carbon Dioxide (CO 2 ) 8) Dark Reactions (Calvin Cycle) 9) Glucose (C 6 H 12 O 6 )

Light Reactions - capture energy in sunlight and transfer it - take place in thylakoid membrane of a chloroplast - chlorophyll absorbs energy from sunlight - water is broken down (into H+ ions, electrons, and oxygen)

Light Reactions (cont) - oxygen is released as a waste product - NADPH is formed (functions like ATP = energy) when electrons are added to NADP+ - energy is transferred to make ATP (when H+ ions diffuse) - overall, oxygen is given off as a waste product, NADPH and ATP are formed

Light Reactions

Light Reaction of Photosynthesis

Dark Reactions (Calvin Cycle) - energy (NADPH and ATP) from light reactions make sugars - occurs in stroma of chloroplast - does not need sunlight

Dark Reactions (Calvin Cycle) (cont) - carbon dioxide is needed - a simple sugar, glucose, is formed from carbon dioxide and energy from ATP and NADPH

Dark Reactions (Calvin Cycle) (cont) - overall, glucose, NADP+, and ADP are created. NADP+ and ADP go back to the light dependent reactions NADP+ and ADP go back to the light dependent reactions

Dark Reactions (Calvin Cycle)

Equation of Photosynthesis

Functions of Photosynthesis - ultimately produces food for all organisms

Energy Flow through an Ecosystem

Functions of Photosynthesis (cont) - provides materials for plant growth/development - simple sugars become starch and cellulose (found in cell walls)

Plant Growth/Development

Functions of Photosynthesis (cont) - helps regulate Earth’s environment - removes CO 2 from atmosphere

Carbon Cycle

Factors that Affect Photosynthesis 1) Light Intensity – as light intensity increases, photosynthesis increases to a point

Factors that Affect Photosynthesis (cont) 2) CO 2 Concentration – as CO 2 concentration, photosynthesis increases to a point

Factors that Affect Photosynthesis (cont) 3) Temperature – as temperature increases, photosynthesis will increase to a point, then a decrease will occur if temperatures continue to increase