Do Now

• Photosynthesis provides most of the energy for life processes. Is energy transfer up a food chain very efficient? Explain.

Ch 8

Photosynthesis Overview, Reactions and Leaf Structure

https://www.youtube.com/watch?v=lqEDz2vfhpQ

Early Discoveries

• Jan Bapiste Van Helmont (1600s)– Wanted to find out if

plants grew by taking material from the soil

– Created experiment to test this and found out most of plant growth was due to water, not the soil

– Helmont concluded that water was important for plant growth

Early Discoveries

• Joseph Priestley– 100 years later in

England– Created experiment

observing a flame under a glass jar

• added mint under the jar and it kept the flame burning

• Realized oxygen produced by the plant kept the flame burning

• https://www.youtube.com/watch?v=pdgkuT12e14

Question of Knowing

• What did Joseph Priestley discover about photosynthesis?

Answer

• He discovered that plants produce oxygen

Early Discoveries

• Jan Ingenhousz– Dutch Biologist/Chemist– Realized plants produced

oxygen only when exposed to light

• Together these discoveries led scientists to understand the process of photosynthesis

I. Photosynthesis

A. Photo = light Synthesis = putting together

B. Plants use light to convert CO2 and H2O into high energy glucose and release O2 as waste.

http://www.youtube.com/watch?v=LgYPeeABoUs

http://www.youtube.com/watch?v=_IV-E68rh18

• Photosynthesis song

• I need a little lightSo I can store energyI need a little lightSo I can make ATPI need a little lightIm gonna make some foodIts outta sightAnd I need a little light

Been sittin here in this chloroplast, feeling green the whole day throughYeah, Im a little thylakoid, waitin for something to doIm gonna move some electrons through a chainThats gonna pump some hydrogen inBut its been dark all night and you can see the state Im in

CHORUS

When the electrons leave the chain theyre gonna join NADP (plus)And that high conconcentration of hydrogens gonna want outside of meGonna go through a special protein thats gonna kick some ATP outThats what movin these electrons is really all about

CHORUS

The ATP and NADPH are gonna make a cycle go roundAt the end of the calvin cycle glucose can be foundYou gotta put in 6 pieces of CO2 to make that precious foodAnd use up the products of the thylakoid, darn this systems good

CHORUS

The chlorophyl that lost the electrons is gonna have to get some moreSo an enzymes gonna break apart water (using 6 no less no more)Its gonna produce 6 molecules of fresh O2, though the plant just thinks its wasteIts amazing to think that this photosynthesis is happening all over the place

Balancelight

C. CO2 + H2O C6H12O6 + O2

Equation

light

C. 6CO2 + 6H2O C6H12O6 + 6O2

Equation

Wavelengths of light

ROY G BIVRed

Orange

Yellow

Green

Blue

Indigo

Violet

D. Chlorophyll in plants absorb all wavelengths EXCEPT green1. Chloro = green

2. green bounces off = leaves appear green

3. plants

would die

if only exposed

to green light

http://scienceunderground.org/science/how-leaves-change-color/

Do Now

• Take out 8.1 homework

• If a plant is exposed to ONLY green wavelengths of light, what will happen to the plant? Explain your reasoning.

E. Parts of a ChloroplastRemember, chloroplasts are found in plant cells!

F. Underside of leaf covered in stomata or guard cells

Stoma control transpiration (water loss) and gas exchange

Exit Card

• If stoma didn’t exist on leaves, how would photosynthesis be affected? What process involving the evaporation of water would also be affected?

Exit Card

• Plant cells contain chloroplasts, which help create glucose. Mitochondria carry out respiration and help break down glucose with the help of oxygen into ATP. Do plant cells need mitochondria too and does this mean they also carry out respiration? Explain.

• https://www.youtube.com/watch?v=eo5XndJaz-Y

III. 2 reactions of photosynthesis

A. Light Dependent Reaction - requires light

1. Thylakoid structures (photosystems) absorb/trap light energy and chlorophyll becomes “energized”

2. Some light energy converted to ATP in chloroplasts (thylakoid)

3. The rest of the light energy is used to split water molecules into H+ and O2 molecules

4. O2 is released as waste

5. H+ are trapped by NADP+ molecule (a carrier molecule) and saved as NADPH

6. Stored ATP and H+ ions in NADPH are saved for the next step

B. Light independent Reaction – light not required (also called Calvin Cycle)

NADPH drops off H+ ions

CO2 molecules are obtained from the atmosphere

ATP energy saved from the light dependent reaction is used to join these together

C6H12O6

molecules created

IV. C6H12O6 importance:

A. Stored and used by plants for energy

B. Eaten by heterotrophs for energy

http://www.youtube.com/watch?v=pE82qtKSSH4

Crash course - http://www.youtube.com/watch?v=sQK3Yr4Sc_k

Photosynthesis rap• Chorus

Photosynthesis, let’s get into thisDiscussion of sunlight, and transfer of energy.Photosynthesis, let’s get into thisProcess of chemical reactions and synergy.

Verse IPlants take water, sun, and CO2,to make glucose: the sugar that they use for foodThey also put oxygen into the airSo we can share, because oxygen is everywhereThe energy transforms from solar to chemicalAll the time, everywhere, the process is identicalIn every plant, and every treeEnabling all living things to be

Chorus

Verse IILet’s take a look at the light reactionMaking chemical energy when light is capturedelectrons flow through the photo systemsFlowing so fast you might have missed ‘emWithin the chloroplast lies the actionThe thylakoid membrane is where it happensATP and NADPHAre products of light, water, air, and space

Chorus

Verse IIIThe Calvin cycle, or dark reactionDoesn’t need direct sunlight for it to run right.CO2 from the air enters the chloroplastMixing with organic molecules for the last timeWith the help of the enzyme RubiscoCarbon Fixation—I thought you knew this yo!It forms a carbohydrate known as G3PIt’s created, recreated, and recycled you see

Chorus

BridgeLeaves on trees and even weeds meet needsMaking oxygen we need to breatheYou want to learn it with ease? You want to master the keys?It’s photosynthesis, listen to this please

Chorus•

V. Factors affecting photosynthesis

A. Water availability

B. Temperature

C. Light intensity (higher the better)

Do Now

• Where do the light dependent reactions occur in the chloroplasts?

• What is the major product of the light independent reactions?