Photosynthesis UnitPhotosynthesis Unit

Energy Flow through an EcosystemEnergy Flow through an Ecosystem

PhotosynthesisPhotosynthesis

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

PhotosynthesisPhotosynthesis (cont) (cont)

- plants absorb visible light for - plants absorb visible light for photosynthesisphotosynthesis

- appears white but is made of a - appears white but is made of a variety of colors (ROYGBIV) = variety of colors (ROYGBIV) = visible spectrumvisible spectrum

PhotosynthesisPhotosynthesis (cont) (cont)

- pigment = a compound that - pigment = a compound that absorbs lightabsorbs light

- different colors absorb different - different colors absorb different colors of lightcolors of light

PhotosynthesisPhotosynthesis (cont) (cont)- chlorophyll = a molecule in chloroplasts that - chlorophyll = a molecule in chloroplasts that

absorbs visible lightabsorbs visible light

- two types: - two types: chlorophyll a (primary chlorophyll a (primary pigment)pigment)

chlorophyll b (accessory chlorophyll b (accessory pigment)pigment)

- absorb mostly red and blue light- absorb mostly red and blue light

- neither a nor b absorbs green light - neither a nor b absorbs green light (this (this is why plants appear green – color is why plants appear green – color is is reflected)reflected)

Structure of Chlorophyll a and Structure of Chlorophyll a and Chlorophyll bChlorophyll b

PhotosynthesisPhotosynthesis (cont) (cont)- carotenoids (accessory pigments) – - carotenoids (accessory pigments) –

contain yellow, orange, red, brown contain yellow, orange, red, brown pigmentspigments

- in plants, chlorophylls are much more - in plants, chlorophylls are much more abundant than other pigmentsabundant than other pigments

- in fall, plants lose their chlorophylls - in fall, plants lose their chlorophylls (carotenoids then become visible)(carotenoids then become visible)

1) Chloroplast1) Chloroplast

2) Sunlight2) Sunlight

3) Water (H3) Water (H220) 0)

4) Thylakoid4) Thylakoid

contains: chlorophyllcontains: chlorophyll

5) Oxygen5) Oxygen

6) Energy transferred to 6) Energy transferred to Dark ReactionsDark Reactions

7) Carbon Dioxide (CO7) Carbon Dioxide (CO22))

8) Dark Reactions (Calvin 8) Dark Reactions (Calvin Cycle)Cycle)

9) Glucose (C9) Glucose (C66HH1212OO66) )

Light ReactionsLight Reactions

- capture energy in sunlight and transfer it- capture energy in sunlight and transfer it

- take place in thylakoid membrane of a - take place in thylakoid membrane of a chloroplastchloroplast

- chlorophyll absorbs energy from sunlight- chlorophyll absorbs energy from sunlight

- water is broken down (into H+ ions, - water is broken down (into H+ ions, electrons, and oxygen)electrons, and oxygen)

Light ReactionsLight Reactions (cont) (cont)

- oxygen is released as a waste product- oxygen is released as a waste product

- NADPH is formed (functions like ATP = - NADPH is formed (functions like ATP = energy) when electrons are added to energy) when electrons are added to NADP+NADP+

- energy is transferred to make ATP (when - energy is transferred to make ATP (when H+ ions diffuse)H+ ions diffuse)

- overall, - overall, oxygen is given off as a waste oxygen is given off as a waste product, NADPH and ATP are formedproduct, NADPH and ATP are formed

Light ReactionsLight Reactions

Light Reaction of PhotosynthesisLight Reaction of Photosynthesis

Dark Reactions (Calvin Cycle)Dark Reactions (Calvin Cycle)

- energy (NADPH and ATP) - energy (NADPH and ATP) from light reactions make from light reactions make sugarssugars

- occurs in stroma of chloroplast- occurs in stroma of chloroplast

- does not need sunlight- does not need sunlight

Dark Reactions (Calvin Cycle)Dark Reactions (Calvin Cycle) (cont) (cont)

- carbon dioxide is needed- carbon dioxide is needed

- a simple sugar, glucose, is - a simple sugar, glucose, is formed from carbon dioxide formed from carbon dioxide and energy from ATP and and energy from ATP and NADPHNADPH

Dark Reactions (Calvin Cycle)Dark Reactions (Calvin Cycle) (cont) (cont)

- overall, glucose, NADP+, and - overall, glucose, NADP+, and ADP are created. ADP are created.

NADP+ and ADP go back to NADP+ and ADP go back to the light dependent reactionsthe light dependent reactions

Dark Reactions (Calvin Cycle)Dark Reactions (Calvin Cycle)

Dark Reactions (Calvin Cycle)Dark Reactions (Calvin Cycle)

Equation of PhotosynthesisEquation of Photosynthesis

Functions of PhotosynthesisFunctions of Photosynthesis

- ultimately produces food for - ultimately produces food for all organismsall organisms

Energy Flow through an EcosystemEnergy Flow through an Ecosystem

Functions of PhotosynthesisFunctions of Photosynthesis (cont) (cont)

- provides materials for plant - provides materials for plant growth/developmentgrowth/development

- simple sugars become - simple sugars become starch and cellulose (found starch and cellulose (found in cell walls)in cell walls)

Plant Growth/DevelopmentPlant Growth/Development

Functions of PhotosynthesisFunctions of Photosynthesis (cont) (cont)

- helps regulate Earth’s - helps regulate Earth’s environment environment

- removes CO- removes CO22 from from

atmosphereatmosphere

Carbon CycleCarbon Cycle

Factors that Affect PhotosynthesisFactors that Affect Photosynthesis

1) Light Intensity – as light 1) Light Intensity – as light intensity increases, intensity increases, photosynthesis increases to photosynthesis increases to a pointa point

Factors that Affect PhotosynthesisFactors that Affect Photosynthesis (cont) (cont)

2) CO2) CO22 Concentration – as Concentration – as

COCO22 concentration , concentration ,

photosynthesis increases to photosynthesis increases to a pointa point

Factors that Affect PhotosynthesisFactors that Affect Photosynthesis (cont) (cont)

3) Temperature – as temperature 3) Temperature – as temperature increases, photosynthesis will increases, photosynthesis will increase to a point, then a increase to a point, then a decrease will occur if decrease will occur if temperatures continue to temperatures continue to increaseincrease