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Photosynthesis

Light from the sun lets plants carry out photosynthesis.

{ adapted from    http://www.biology4kids.com/files/plants_photosynthesis.html }

Light carries energy. When that energy gets to a green plant, chemical reactions take place, which store energy in sugar molecules.

Not all the energy from the Sun is used by plants.
Plants mostly absorb red and blue wavelengths.
When you see the green color of a leaf, green is the color that the leaf does NOT absorb.
Green plants do not absorb green light – rather, they reflect it.
Here is the simple version:

Here is a more complete version:

Image below from http://missionscience.nasa.gov/ems/08_nearinfraredwaves.html

Plant abosrb Red Blue reflects Green spectra
http://pinklightaeroponics.net/science-pink-light-aeroponics/science-of-futuristic-aeroponic-indoor-gardening-with-pink-led-grow-lights-photosynthesis-light-spectrum-optimization/

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Plants are autotrophs – they make their own energy (from sunlight)

Animals are heterotrophs – get their energy from multiple sources (plants and other animals)

Plant cells contain organelles called chloroplasts

Chloroplasts contain a pigment (colored molecule) called chlorophyll.

Chlorophyll captures light, and traps that energy in sugar molecules.

II. The chloroplast

Plant cells contain organelles called chloroplasts

Chloroplasts contain a pigment (colored molecule) called chlorophyll.

Chlorophyll captures light, and traps that energy in sugar molecules.

 

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1. nucleus    2. nucleolus    3. lipid bilayer (cell membrane)    4. cytoplasm
5. cell wall    6. vacuole      7. chloroplast
Structure of a chloroplast

Chloroplast structure Thylakoid Granum

III: THE MOLECULES

Water H2O Carbon dioxide gas CO2

Oxygen gas O2 Glucose (a sugar) – C6H12O6
Glucose is a sugar, used by every creature on the planet.
Animal and plant cells require oxygen to survive.

Chemistry Photosynthesis

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photosynthesis and respiration color diagram

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  1. What is photosynthesis? P.195

 

  1. The process by which organisms take energy from the Sun, and use it to combine CO2

and H2O  to make sugars.

 

 

  1. What kinds of life utilize photosynthesis?

 

  1. It occurs in all plants

 

  1. Occurs in some Protista

 

III. Where does photosynthesis take place?   P.195

  1. Plants have leaves. Each leaf is made up of millions of cells.

 

  1. Each cell has many greenish organelles that look like a stack of pancakes.
  2. Each little “pancake” is called a thylakoid.
  3. A stack of them is called the granum.

 

  1. How does photosynthesis work?
  2. How do plants get material to build more plant?
  3. How can plants get energy?
  4. They take energy from the sun, and use it to build sugar,
  5. Light energy + water + carbon dioxide  =>  glucose + oxygen

 

  1. Problem – Sun is only shining a part of the day. How do we store energy for use at night?
  2. Light dependent reaction: this part only happens in light

 

Thylakoids take in water (H2O) and light

 

It uses the energy from light to break apart the water molecule   H2O  =>  H   O   O

 

Some of the O goes off to form O-O    O2   oxygen gas       (This is what we breathe)

 

The H atoms are used to “power up” two types of battery molecules

 

NADP+                                    +          H           =>       NADPH

 

Low power form of battery                                          High power form of battery

 

 

Energy from the light is also used to add a phosphorous atom (P) to ADP

 

ADP                                         +          P          =>        ATP

 

Low power form of battery                                          High power form of battery

 

  1. Light independent reaction – Uses the battery molecules.

 

  1. Can occur anytime, even in the dark.

 

  1. Occurs in the fluid outside the thylakoids – the stroma

 

  1. Energy from NADPH and ATP is used to break apart CO2, and build C6H12O6 (sugar)

 

NADPH loses energy and H, turns back into NADP+    (low power form)

 

ATP loses energy P, turns back into ADP   (low power form)

 

  1. ADP and NADP+ get recycled during the light cycle (they are rechargeable batteries)

 

Learning Standards

Massachusetts Curriculum Frameworks: Biology

HS-LS1-5. Use a model to illustrate how photosynthesis uses light energy to transform water and carbon dioxide into oxygen and chemical energy stored in the bonds of sugars and other carbohydrates.

Clarification Statements: Emphasis is on illustrating inputs and outputs of matter and the transfer and transformation of energy in photosynthesis by plants and other photosynthesizing organisms.

State Assessment Boundary: Specific biochemical steps of light reactions or the Calvin Cycle, or chemical structures of molecules are not expected in state assessment.

 

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