Light Absorption

• Sun gives off visible (white) light• White light is actually a mixture of ROY G BIV

– Red, Orange, Yellow, Green, Blue, Indigo, Violet

White lightHow do we know this?

Prism

Moisture in the air can act like a prism and create a RAINBOW

Light Absorption

• Sun gives off visible (white) light• White light is actually a mixture of ROY G BIV

– Red, Orange, Yellow, Green, Blue, Indigo, Violet

• These colors are either reflected or absorbed by objects

• We see reflected light– Green leaves = reflect green light

Which color(s) reflects?Yellow

Which color(s) absorb?All the others

I see yellow bananas.

Example

Which color(s) reflects?Blue

Which color(s) absorb?All the others

I see a blue balloon.

I see white snow.

Which color(s) reflects?All

Which color(s) absorb?None

I see a black car (although I’m really

seeing nothing).

Which color(s) reflects?None

Which color(s) absorb?All

The Full Spectrum of Energy from the Sun

Our eyes can only sense this small area called “visible light”

• Most plants have green leaves, which means they:– Reflect green light– Absorb other colors

• Energy in red and blue light most stimulates photosynthesis

Light & Photosynthesis

• Defined: process that converts solar energy into glucose• Who: Autotrophs (Plants, algae, some bacteria & protists)• What: Endothermic chemical reaction

– Requires energy & MORE energy absorbed• End Result:

1. Sugar (glucose) stored in plant2. Oxygen as a waste product

reactants products

Photosynthesis

O2

• Where: Thylakoid membranes of chloroplast• What happens?

1) Sunlight & enzymes bond ADP with P to make… ATP

2) Water (H2O) broken apart

• Hydrogen kept for later use; Oxygen is released as a waste• End result: ATP, H2, Oxygen

Stage 1: Light Dependent (Light Reactions)

H2O

H2O H2O

H2O

Stroma

enzymesenzymes

ADP

P

ADP

P

ATPATP

Thylakoids

60 seconds: Discuss with your neighbor

1) Are the products of photosynthesis on the left or right of the arrow?

2) Which reactant(s) are used during the light dependent stage?

3) Which product(s) are created during the light dependent stage?

reactants products

#2 #3

Stroma

• Where: Stroma (fluid interior) of chloroplast• What happens?

A) CO2 taken in

B) ATP & enzymes break apart CO2 + H2

C) C’s, O’s, and H’s recombine into C6H12O6 (Glucose)

Stage 2: Light Independent (Dark Reactions)

H2

H2

H2

H2

ATP

ATP

CO2

CO2

CO2

CO2

CO2

CO2 H2

H2

COOCOO

COO

COO

COO

COOenzymes

enzymes

HH

HHHH

HH

HH

HH

What’s the formula for glucose?

C6H12O6

60 seconds: Discuss with your neighbor

1) Which reactant(s) are used during the light independent stage?

2) Which product(s) are created during the light independent stage?

reactants products

#1 #2

Connection between photosynthesis & respiration

• Plants– Create glucose through photosynthesis– Glucose is used to make ATP through cellular

respiration

Plant Cell

glucose

glucosechloroplast

chloroplast ATP

ATP

mitochondrion

mitochondrion

Connection between photosynthesis & respiration

• Animals– Plants create glucose through photosynthesis– Animals eat the plants – Glucose is used to make ATP through cellular

respiration

Glucose

mitochondrionATP

Glucose(from food)

Review1) Which color(s) is/are absorbed by a typical red

apple?2) Which color(s) is/are reflected by a typical red

apple?3) Which color light produces the highest rates of

photosynthesis?4) What is used during the light dependent

reactions?5) What is created during the light dependent

reactions?6) What is used during the light independent

reactions?7) What is created during the light independent

reactions?8) True or False: Plants are the only

photosynthetic organisms.

1) Which color(s) is/are absorbed by a typical red apple?• All the colors except red

2) Which color(s) is/are reflected by a typical red apple?• Red

3) Which color light produces the highest rates of photosynthesis?• Blue

4) What is used during the light dependent reactions?• *H2O | Light Energy | Enzymes | ADP | P

5) What is created during the light dependent reactions?• *O2 | H2 | ATP (the O2 and H2 are created when the water splits)

6) What is used during the light independent reactions?• *CO2 | H2 | ATP | Enzymes

7) What is created during the light independent reactions?• *C6H12O6

8) True or False: Plants are the only photosynthetic organisms. False

Answers to Review

#9