11/13

• Turn in ATP lab

• Go over ATP HW

• Photosynthesis Notes

• Photo. Vocab (due by end of class)

• Quick review (What's not done is HW)

Bio NOTES: PhotosynthesisWe know from previous lessons that all living things needenergy in order to survive, and that food provides the sourceof energy. But…where does the food come from?

Food is made by producers, such as plants and algae.

Photosynthesis = process where plants use energy from the sun to make their own food

Plants are also known as autotrophs because they maketheir own food by the process of photosynthesis.

Producers capture energy from sunlight to make their own source of chemical energy!

Chemical Equation

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

In plants, chlorophyll is found inorganelles called chloroplasts.

Plants contain pigments that absorb sunlight and trap energy.The most common pigment is chlorophyll, which givesplants their green color.

Plants also contain red and orangepigments such as carotene thatabsorb light in other regions of thespectrum.

The spectrum of visible light

Energy from the sun travels to Earth in the form oflight. Sunlight is a mixture of differentwavelengths of light – many of these are visibleto your eyes.

• Plants absorb red and blue light from the sun to make food during photosynthesis

• Plants don’t need green light to make food, so it is reflected – which is why plants are green!

So…the best wavelengths of light for plant growth are red and blue while the worst wavelength of light for plant growth is green.

http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS12/LS12.html

Inside the chloroplast

Photosynthesis occurs in chloroplasts.There are two major parts of a chloroplast: - grana (thylakoids) - stroma

● grana (thylakoids) - saclike membranes arranged in stacks - contains pigments - first part of photosynthesis occurs here

● stroma - region outside the thylakoid membranes - second part of photosynthesis occurs here

Light-Dependent ReactionsThe light-dependent reactions capture energy from sunlight. - takes place in thylakoids - water and sunlight are needed. -Water is absorbed through the roots - chlorophyll absorbs light energy - energy (ATP) is transferred along thylakoid membrane then to light-independent reactions - oxygen is released

Light-Independent Reactions

The light-independent reactions make sugar. - takes place in the stroma - needs carbon dioxide from atmosphere - uses energy (ATP) from light-dependent reaction to build a sugar in a cycle of chemical reactions

* Also called the Calvin cycle

C6H12O6

granum (stack of thylakoids)

thylakoid

sunlight

1 six-carbon sugar

6H2O

6CO2

6O2

chloroplastchloroplast1

2

43

energy

stroma (fluid outside the thylakoids)

6CO2 + 6H2O + sunlight C6H12O6 + 6O2

The equation for the overall process is:

Factors affecting Photosynthesis

● Water - shortage can slow or even stop photosynthesis - plants living in dry areas have a waxy coating to prevent water loss

● Temperature - enzymes used in photosynthesis function best between 0°C and 35°C - high or low temps slow down or stop photosynthesis

● Intensity of light - increasing light intensity increases the rate of photosynthesis - plants eventually reach their maximum rate of photosynthesis

Summary of Photosynthesis

Light Reactions

• Inputs:

Light

Water• Outputs:

ATP

Oxygen (O2)

OCCURS IN THYLOKOID

Dark reactions (Calvin cycle)

• Inputs:

◦ ATP

◦ CO2• Outputs:

◦ Glucose

OCCURS IN THE STROMA

Summary• Light reactions Calvin Cycle

Thylakoid StromaStroma

Glucose

Let’s review…

Light-d

ep

end

ent

reactio

ns

Lig

ht-

ind

ep

end

ent

react

ions

What materials come into the chloroplast that are used in the

light-dependent reactions?

What material comes into the chloroplast that is used by the

Calvin Cycle?

What material moves out of the chloroplast from the light-

dependent reactions?

What materials move out of the chloroplast from the Calvin Cycle?

What materials move from the light-dependent reactions to the Calvin

Cycle?

What materials move from the Calvin Cycle back to the light-

dependent reactions?

11/13

• Turn in ATP lab

• Go over ATP HW

• Photosynthesis Notes

• Photo. Vocab (due by end of class)

• Quick review (What's not done is HW)