PhotosynthesisChapter 8

PhotosynthesisChapter 8

Objectives:3.0 Identify reactants and products associated with

photosynthesis and cellular respiration and the purposes of these two processes.

AOD B.3.1 Identify the function of photosynthesis and cellular respiration.

AOD B.3.2 Describe photosynthesis and cellular respiration, including their reactants and products.

AOD B.3.3 Recognize the relationship between reactants and products associated with photosynthesis and cellular

respiration. AOD B.3.4 Recognize a given formula as either

photosynthesis or cellular respiration.

Objectives:3.0 Identify reactants and products associated with

photosynthesis and cellular respiration and the purposes of these two processes.

AOD B.3.1 Identify the function of photosynthesis and cellular respiration.

AOD B.3.2 Describe photosynthesis and cellular respiration, including their reactants and products.

AOD B.3.3 Recognize the relationship between reactants and products associated with photosynthesis and cellular

respiration. AOD B.3.4 Recognize a given formula as either

photosynthesis or cellular respiration.

What Do You Know?

Complete “Before Reading” portion of Photosynthesis Anticipation/Reaction Guide.

Section 8-1

• Are plants autotrophs, chemotrophs, or heterotrophs?

• Energy can be found in many forms: light, heat, electricity, chemical bonds.….

• Which form(s) is(are) used by plants?

• ATP (adenosine triphosphate) – composed of adenine, ribose, and 3 phosphate groups:

• ATP is converted to ___, ____, and ____.

Source: http://faculty.ccbcmd.edu/biotutorials/energy/adpan.html

• Cells only store enough ATP for a few seconds of activity: active transport, synthesis of proteins or nucleic acids, movements within the cell, etc..

• ATP is great for transferring energy, but not storing it.

• Glucose can store 90 times more chemical energy than ATP.

Section 8-2• What do plants need to carry

out photosynthesis? Water (H2O), carbon dioxide

(CO2) , and sunlight --- These are called reactants.

• What do plants produce in photosynthesis?

Glucose (C6H12O6) and oxygen (O2) --- These are the products.

Important Historical Discoveries

• Jan van Helmont (1643):– Common belief: plants took

material out of the soil to grow.– Van Helmont grew a tree for 5

years. By comparing the mass of the dry soil and seedling to the mass of the soil and small tree, he concluded that most of the gain in mass came from water.

• Joseph Priestly (1771):– Put a lit candle under a bell jar. What

do you think happened?– Determined the air in the jar was

“injured”.– Wanting to see the effects of “injured

air” on living material, he placed a mint sprig under the jar for a few days.

– When it remained green, he relit the candle, and it remained lit for a while.

– He concluded the plant “cured” the injured air.

– What actually occurred?

• Jan Ingenhousz (1779):– Repeated Priestley’s experiments

using aquatic plants– Found the plants only produced

gas bubbles when the plant was exposed to sunlight

– http://www.reading.ac.uk/virtualexperiments/ves/preloader-photosynthesis-full.html

• Melvin Calvin (1948): – Traced the path taken by carbon

to form glucose in plants.

Photosynthesis Equation

6CO2 + 6H2O C6H12O6 + 6O2

Entrance Slip: Which scientist is responsible for the discovery of the different parts of this equation?

sunlight

Water Weed Lab – Virtual Photosynthesis Inquiry

• http://www.cbsd.org/sites/teachers/hs/mgleicher/Class%20Documents/Labs/Lab%20-%20Water%20Weed.pdf

• Complete lab write-up in your lab notebook.

• See if your results match up with the information found on p.207 of your textbook.

Lab Review• What color of light will NOT

produce photosynthesis in plants?

• WHY?????• Green light is not ABSORBED

by plants. WHY NOT???• Why are leaves green?• Why do leaves turn red,

yellow, and orange in the fall?

Spinach Chromatography

Source: http://www.chemistryland.com/CHM130FieldLab/Lab5/Lab5.html

Section 8-3

• Photosynthesis Overview handout• Photosynthesis – Biology in a Few

Minutes: http://www.youtube.com/watch?v=BeUmj8d6Mag&feature=related&continue_action=afvxnCArL3KfYDYfH0vIq5jDaERLtzjb5GDbVUH6nVH6tBB8lP3QfqliBotcIa747RJlWQzLFT4nhJ_U2URLglOUUOSynR1CEMIXwl7BHPA=

• Photosynthesis (BozemanScience): http://www.youtube.com/watch?v=g78utcLQrJ4&feature=relmfu

Inside a Chloroplast

• Thylakoids: – saclike photosynthetic

membranes– Arranged in stacks called grana

• Photosystems:– Clusters of chlorophyll and other

pigments – The light-collecting units of the

chloroplasts

2 Photosystems• “Light-dependent reactions”:

– Take place in the thylakoid membranes

– Requires: light and H2O

• Photosystem II:– Light activates/energizes

electrons, which then enter the electron transport chain.

– Electrons are replaced by H2O, as it breaks down into 2 e-’s, 2 H+’s, and 1 oxygen atom.

Electron Transport Chain

• Light hitting chlorophyll excites electrons, causing them to gain energy.

• Electron carriers take these electrons from the chlorophyll to other molecules in…….

• Photosystem I:– Light energy reenergizes the

electrons– e-’s cause more H+ to be pumped

into the thylakoid lumen, making it positive, and stroma negative.

– NADP+ can hold 2 e-’s and H+, and become NADPH, storing energy.

– H+ is transported back outside the membrane, in an effort to reestablish equilibrium, by a protein called ATP synthase, converting ADP to ATP.

Photosystems I and II

http://nathanielzhu.hubpages.com/hub/Understanding-Light-Dependant-Photosynthesis

Electron Transport Chain• http://www.mhhe.com/biosci/

genbio/biolink/j_explorations/ch09expl.htm

• Recap: – Light-dependent reactions use

____, ___, _____, ____, and _____.– They produce high energy ____

and ______, and release ______ as a waste product.

Calvin Cycle

• Light-independent (AKA, Calvin cycle)

– Take place in the chloroplast stroma – fluid-filled space outside the thylakoid membranes

– Requires CO2

– Uses the high-energy products of the light-dependent reactions! (?????)

• CO2 from the air combines with 5-carbon sugars to form 3-carbon sugars.

• ATP and NADPH convert these sugars to higher energy sugars.

• 2 of these sugars form the 6-carbon glucose molecule and other compounds needed for plant metabolism and growth.

• Other 3-carbon sugars are converted back to 5-carbon to repeat the cycle.

Calvin Cycle Review• If ATP’s energy is used, what

does the ATP become?• NADPH is converted back to

_____.• Is light used in the Calvin cycle?• What atmospheric gas is used

in the Calvin cycle?• What are the end products?