Photosynthesis

Ch. 9

Kansas Science Standards

The sun is the primary source of energy for life through the process of photosynthesis.-plants and other photosynthetic organisms use energy from the sun to make glucose.- photosynthesis is a series of chemical reactions that takes place in a chloroplast.

Energy for Life; all living things need energy!

Without energy, things tend to get messy.

ex: your room, death

Entropy: natural tendency toward disorder.

Autotrophs:

get energy from the sun (or chemicals) to make own

food.

Heterotrophs:

obtain energy from food it eats.

Energy is stored in the bonds between atoms and molecules (food) = chemical energy

Plants change light energy into chemical energy which is stored in the bonds of glucose molecules.

sun

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

Carbon water oxygen glucose

dioxide

Photosynthesis

Glucose = C6H12O6

The carbon in glucose comes from carbon dioxide (CO2)

The hydrogen comes from water (H2O)

The oxygen comes from CO2.

The sun energy is stored in the bonds that hold the molecule together.

Plants take in carbon dioxide

Pore on bottom of leaf called stoma (stomata pl.).

Let CO2 into leaf.

Let water vapor out.

Plants get water through roots

Water is absorbed from soil through the roots.

Photosynthesis

Photosynthesis happens in the chloroplast of a plant cell.

Chloroplast

Thylakoids - membrane bound disks

Granum - stack of thylakoids.

Stroma - juicy inside.

Double membrane around outside.

Plants gather sun energyPigments: molecules that absorb certain wavelengths of light energy.

Chlorophyll: pigments that absorb mostly blue and red wavelengths and reflect green.

Products of photosynthesis:

Makes glucose to store energy.

Also stores energy short term in the molecule ATP.

ATP: adenosine triphosphate

Small molecule that stores small amounts of energy for a cell.

Like pennies of energy compared to the $20 bill of glucose.

Energy in ATP can be used anywhere in the organism.

ATP

Energy is stored in the bond of the last phosphate group.

Like a rechargeable battery.

Absolutely necessary for life processes!

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

Factors affecting Photosynthesis

Water

Temperature

Intensity of light

Concentration of CO2

Overview of Photosynthesis

Two Parts:

Light-dependent reactions

Light-independent reactions

Light-dependent reactions

Happens within thylakoid membrane.

Chlorophyll energized by sunlight. (needs light)

Sun energy moves to ATP and NADPH. (energy carriers)

Oxygen produced.

NADPH

Another energy carrying molecule like ATP.

Like a rechargeable battery.

Light-independent reactions

Happens in the stroma of chloroplast.

Uses energy from light-dependent reactions (ATP and NADPH) to make glucose from CO2.

Does not need light to work.