+

Photosynthesis: Converting sunlight into chemical

energy

Students who demonstrate understanding can:

HS-LS1-5: Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.

+Where does the oxygen (O2) we

breathe come from?

O2 is produced by different

kinds of bacteria, algae, and

plants (including trees)

during photosynthesis.

About 25% of O2 comes from

land plants.

Most of Earth’s O2 comes

from the ocean.

Released from tiny ocean plants

called, phytoplankton.

+Autotrophs and Photosynthesis

Called “self feeders” or

”producers”.

Organisms that can produce their

own food using light, water,

carbon dioxide, or other

chemicals.

Examples of autotrophs: green

plants, some algae, few bacteria.

Most autotrophs use

photosynthesis to make their

food.

+Overview of Photosynthesis

Light energy gets converted into chemical energy.

Chemical energy is stored in the form of glucose (sugar).

Carbon dioxide, water, and sunlight are used to produce carbohydrates and oxygen.

Occurs in two stages:

Light Dependent Reactions

Light Independent Reactions

https://www.youtube.com/wa

tch?v=1XilneV3cJI

+Where Does Photosynthesis Take Place

in the Cell?

+Chloroplast Anatomy:

+Closer Look at Chloroplast

Structures

Chlorophyll:

Allows plants to absorb energy from light

Gives leaves their green color

Membrane Envelope:

Inner and outer membranes

Protects and keep chloroplast structures enclosed.

Thylakoid membrane:

Internal membrane system

Flattened sac-like membrane structures called thylakoids

Serve as the sites of conversion of light energy to chemical energy.

Granum

Dense layered stacks of

thylakoid sacs

Sites of conversion of light

energy to chemical energy.

Stroma

Dense fluid within the chloroplast

Lies inside the envelope but

outside the thylakoid membrane

Site of conversion of carbon

dioxide to carbohydrates

+

Two Processes of Photosynthesis

Location: Thylakoid Membrane

Reactants: Sunlight and water

(H2O)

End Products: ATP, NADPH,

and O2

Also called “Calvin Cycle” or

Dark Reactions

Location: Stroma

Reactants: ATP, NADPH, and

O2

End Products: Glucose

Light Dependent Reactions Light Independent Reactions

Remember:

Cells use ATP for energy

NADPH is a cofactor in reactions that acts as a reducing agent

+How Does It All Work?

+Photosynthetic Equation

Photosynthesis can be represented using a balanced chemical

equation:

+Why is photosynthesis essential to life

on Earth?

Well..

Life can be sustained in plants.

Plants provide oxygen for

humans.

We BREATHE oxygen!

Without oxygen we cannot

survive!