Photosynthesis

Lock and Key of Earth

Topic #2015Matt Jakubik

Why Learn About Photosynthesis?

• Photosynthesis is the most important chemical reaction on earth.

What is it?

• Process plants use to convert carbon dioxide and water into sugar and oxygen

Picture taken from Life: The Science of Biology, 4th edition, by Sinauer Associates and WH Freeman

Plants as Autotrophs

• Autotrophs: Make their own energy

• Heterotrophs: Get energy from other living organisms

Light• How do plants make their energy?

• Is all light the same?

• The more the better?

• What properties does light have?

Wavelength

is the

symbol for wavelength

• Energy of light is inversely related to the wave length

Picture taken from Life: The Science of Biology, 4th edition, by Sinauer Associates and WH Freeman

Light quality• Spectrums

• Visible light

• Plants mainly use Red and Blue

• Why are plants green?

Picture taken from Life: The Science of Biology, 4th edition, by Sinauer Associates and WH Freeman

Light Quantity

• Measured in micromoles/m²

• Light quantity is the amount of light that hits a surface

• What variables can you think of that would affect light quantity?

Duration• Generally referred to as daylength in

the field.• Affects flowering, bulbset, tuberset,

germination, budset… etc.

• What are some benefits of greenhouse lighting? (think back to what we discussed in the last slide)

Two Types of Photosynthesis

C3-has 3 carbon chainsC4-has 4 carbon chains

C3 Plants

Cannot increase increase rate of photosynthesis when light intensity is greater than 1/3-1/2 full sunlight

Examples-soybeans, cotton, potatoes, alfalfa, sugarbeets, cool season grasses

C4 Plants

Can continue to increase their rate of photosynthesis past full sunlight

Examples-corn, sorghum, sugarcane, and warm season grasses

So Where Does the Light Go to Do It’s Thing?

Plant Cell Structure• The following are

important to know• Xylem• Phloem• Guard cell• Stoma• Chloroplasts

Picture taken from Life: The Science of Biology, 4th edition, by Sinauer Associates and WH Freeman

Plant Organelle Function

• Xylem• Phloem• Guard Cell• Stomata

Stomata

Picture taken from Life: The Science of Biology, 4th edition, by Sinauer Associates and WH Freeman

The All Important Chloroplast

• What is the chloroplast?

• What is chlorophyll?

• Thylakoids?

Picture taken from Life: The Science of Biology, 4th edition, by Sinauer Associates and WH Freeman

Formula for photosynthesis

6H2O + 6CO2 ----------> C6H12O6+ 6O2

In English terms.Where does light fit in?

Factors affecting photosynthesis

• CO2 concentration• Temperature• Available water• Light