Photosynthesis

6CO2 + 6H20 C6H1206 + 6O2

Reactants yield Products

Photosynthesis Involves concepts from

BiologyPhysicsChemistry

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)

ORcompounds 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.  

2H2O + Heat ENERGY 2H2 + O2

 Energy can be stored for later use.

Chemical Reaction-Formation of Water

+

Forms

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PhysicsWhite 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*

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 colorWhat is the color of a sweater that absorbs blue,

green and yellow light?

What colors are absorbed by

Green Plants?

Green PlantsReflect green light

Absorb all other colors of light

Green Plants

BiologyOrganisms make their own food and are called

autotrophs

Or Organisms EAT plants or animals and are called

__________________________________ heterotrophs

BiologyAutotrophs 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 EnglandJoseph 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 ConclusionGreen plants only produce oxygen in the

presence of _______________.Sunlight

PhotosynthesisBy the mid-1800’s, it was understood that plants

produce glucose (carbohydrates) and oxygen using light energy and carbon dioxide and water.  

Photosynthesis Reaction: 6CO2 + 6H2O + C6H12O6 + 6O2

PhotosynthesisCO2 enters

plants through stomata in leaves and stem.

O2 and water exit the stomata

Carbon Dioxide

WaterH2O 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.

PhotosynthesisComplete 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!H2O enters chloroplast through veins

Chemical bonds holding H2O together are broken apart by light energy

6H2O

HHHHHHHHHHHHOOOOOO

Light Dependent ReactionThe 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 Cycle1. Takes place in light OR dark

Light Independent Reaction or Calvin Cycle2. CO2 enters chloroplasts through stomata.

3. Energy stored in ATP is used to convert the CO2 + the H+ (from water) into glucose.

Light Independent Reaction or Calvin Cycle

Chemical Energy in ATP

H+ + CO2 Glucose HIGH ENERGY

BONDS

Photosynthesis Equation!

6CO2 + 6H20 C6H1206 + 6O2

Reactants Products

Factors affecting Photosynthesis

1. Light - Absence of light no photosynthesis

2. 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?

3. Water - Absence of water slows or stops the process

Factors affecting Photosynthesis

4. 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 CO2 to be a problem for plant growth on earth? Why or why

not?

Photosynthesis – Putting it all together

H+