Photosynthesis 6CO 2 + 6H 2 0  C 6 H O 2 Reactants yield Products

Photosynthesis Involves concepts from Biology PhysicsChemistry

Organisms exist because of chemical reactions occurring within cells. Chemical reactions occur in all cells, tissues, organs, and organ systems. Digestive System

What is a chemical reaction? Atoms or ions are joined together by chemical bonds (forming a compound) OR compounds are broken apart All chemical reactions involve a rearrangement of atoms or ions AND

Energy

Law of Conservation of Energy Energy cannot be created or destroyed, however it can change forms. Energy must be added to water to break it down. This added energy ends up stored in chemical bonds of hydrogen and oxygen molecules. 2H 2 O + Heat ENERGY  2H 2 + O 2 Energy can be stored for later use.

Chemical Reaction-Formation of Water +

Forms +

Physics White light is made up of a spectrum of colors.

Physics The spectrum is seen when the white light is broken up into its components by prisms or raindrops*raindrops*

Light When all colors within white light are reflected back to our eyes  we see WHITE! When all colors within white light are absorbed by an object  we see BLACK! A surface appears a particular color because it contains a "pigment" that reflects that particular color and absorbs all other colors. Pigment = light absorbing colored molecule

Name the color What is the color of a sweater that absorbs blue, green and yellow light?

What colors are absorbed by Green Plants?

Green Plants Reflect green light Absorb all other colors of light

Green Plants

Biology Organisms make their own food and are called autotrophs

Or Organisms EAT plants or animals and are called __________________________________ heterotrophs

Biology Autotrophs use light energy from the sun (or chemical energy) to produce energy rich sugars/carbohydrates. Examples of autotrophs: _____________________,________________, ____________________________ some protistagreen plants some bacteria Energy in most ecosystems on earth comes from

Early Scientific Research on Photosynthesis 1643 – Belgium Jan van Helmont With the class: analyze van Helmont’s experiment

Conclusions from van Helmont’s experiment “…164 pounds of wood, bark, and roots had arisen from water alone.” The mass of the tree did NOT come from the soil. Was van Helmont correct? _____________________ Partially correct The mass of a plant comes in part from water…NOT from soil (except for a tiny fraction) Plants are made of carbohydrates. The term “hydrate” = water.

Late 1700’s England Joseph Priestley Joseph Priestley discovered oxygen in 1774 He continued to experiment with gases, plants and animals. With the class analyze Priestley’s experiment!

Priestley’s Photosynthesis Experiment Priestley concluded green plants produce the substance “oxygen” necessary for a fire to burn and for animal’s to breathe.

Late 1700’s Jan Ingenhousz’s Jan Ingenhousz was born in 1730 in the Netherlands. He trained as a medical doctor. In 1779, Ingenhousz took a position in the same laboratory as Joseph Priestley. Ingenhousz carried out research on photosynthesis.

Ingenhousz’s Photosynthesis Experiment Ingenhousz placed a pond plant in a jar filled with water He placed the jar in bright sunlight and observed bubbles produced by the plant He placed the jar in low light conditions and observed no bubbles produced by the plant

Ingenhousz’s Conclusion Green plants only produce oxygen in the presence of _______________. Sunlight

Photosynthesis By the mid-1800’s, it was understood that plants produce glucose (carbohydrates) and oxygen using light energy and carbon dioxide and water. Photosynthesis Reaction: 6CO 2 + 6H 2 O +  C 6 H 12 O 6 + 6O 2

Photosynthesis CO 2 enters plants through stomata in leaves and stem. O 2 and water exit the stomata

Carbon Dioxide

Water H 2 O enters plants through roots and is carried by the veins to leaves Water travels through the plant’s veins from the roots to the leaves

Products of Photosynthesis Glucose and Oxygen Glucose is carried in veins from the leaves of the plant to the parts of the plant where photosynthesis does not occur. Glucose is stored in fruits Oxygen is released from stomata.

Photosynthesis Complete worksheet on Green Plants!

What else is needed for Photosynthesis? Photosynthesis occurs in the chloroplasts of plant cells.

Chloroplast

If plants contain chlorophyll why do they turn color in the fall?

Processes of Photosynthesis Two Stage process: Light DEPENDENT reaction and Light INDEPENDENT reaction or CALVIN CYCLE

LIGHT DEPENDENT REACTION Occurs only in light! H 2 O enters chloroplast through veins C hemical bonds holding H 2 O together are broken apart by light energy 6H 2 O HHHHHHHHHHHHOOOOOO

Light Dependent Reaction The energy from the water molecules is stored in high energy molecules called ATP. O2 is released through stomata. It is a “waste” product of photosynthesis. This is the oxygen we breathe. H is saved for making glucose!

Fact Check – Light Dependent Reaction 1. What is the “waste product” of the light dependent reaction? 2. How does this waste product exit the plant cells? 3. Which part of the water molecule is saved to make a molecule of glucose? 4. What is the role of sunlight in the process of photosynthesis?

Light Independent Reaction or Calvin Cycle 1. Takes place in light OR dark

Light Independent Reaction or Calvin Cycle 2. CO 2 enters chloroplasts through stomata. 3. Energy stored in ATP is used to convert the CO 2 + the H + (from water) into glucose.

Light Independent Reaction or Calvin Cycle Chemical Energy in ATP H + + CO 2  Glucose HIGH ENERGY BONDS

Photosynthesis Equation! 6CO 2 + 6H 2 0  C 6 H O 2 Reactants Products

Factors affecting Photosynthesis  Light - Absence of light  no photosynthesis  Increase in light intensity increases rate of reaction (up to a point—this point is dependent on the particular species of plant) Which stage of the photosynthetic process would be affected? Which reactant would be affected? Which other molecules would be affected?

 Water - Absence of water slows or stops the process Factors affecting Photosynthesis

 Temperature – Occurs at 0°C  35°C (32°F – 95°F) Which state of matter is water in when temperatures are below 0°C? What happens to enzymes when temperatures increase? What happens to the rate of transpiration when temperatures increase? Factors affecting Photosynthesis Would you expect a shortage of CO 2 to be a problem for plant growth on earth? Why or why not?

Photosynthesis – Putting it all together H+H+