Photosynthesis

Light Absorption Sun gives off visible (white) light How do we know this? Sun gives off visible (white) light White light is actually a mixture of ROY G BIV Red, Orange, Yellow, Green, Blue, Indigo, Violet

Prism White light

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

Example Which color(s) reflects? Yellow Which color(s) absorb? All the others I see yellow bananas. Objects have pigments that absorb certain wavelengths of light and reflect others

Which color(s) reflects? Blue Which color(s) absorb? All the others I see a blue balloon.

Which color(s) reflects? All Which color(s) absorb? None I see white snow.

I see a black car (although I’m really seeing nothing). Which color(s) reflects? None Which color(s) absorb? All I see a black car (although I’m really seeing nothing).

The Full Spectrum of Energy from the Sun Our eyes can only sense this small area called “visible light”

Light & Photosynthesis Most plants have green leaves, which means they: Reflect green light (CHLOROPHYLL IS THE PIGMENT) Absorb other colors Energy in red and blue light most stimulates photosynthesis

Photosynthesis O2 CO2 reactants products Defined: process that converts solar energy into glucose Who: Autotrophs (Plants, algae, some bacteria & protists) What: Endothermic chemical reaction Requires energy & MORE energy absorbed & CO2 & H2O End Result: Sugar (glucose) stored in plant Oxygen as a waste product

PHOTSYNTHESIS Occurs in 2 stages 1. light dependent reactions 2. light independent reactions Calvin Cycle

Stage 1: Light Dependent (Light Reactions) Stroma H2 O ADP H2 O ADP ATP enzymes enzymes ATP H2 O P P H2 O Thylakoids Where: In the grana (thylakoid membranes) What happens? Water (H2O) broken apart Hydrogen ions; electrons; Oxygen is released as a waste 2) Sunlight & enzymes bond ADP with P to make… ATP and NADPH End result: ATP, H2, Oxygen

60 seconds: Discuss with your neighbor #3 #2 reactants products Are the products of photosynthesis on the left or right of the arrow? Which reactant(s) are used during the light dependent stage? Which product(s) are created during the light dependent stage?

Stage 2: Light Independent (Calvin Cycle) Stroma H2 H H ATP CO2 C O O CO2 C O O H2 H H H H2 H C6 H12 O6 enzymes enzymes CO2 C O O C CO2 O O CO2 C O O H H H2 ATP H H2 H H2 H H C CO2 O O What’s the formula for glucose? Where: Stroma (fluid interior) of chloroplast What happens? CO2 taken in and ATP and NADPH from step 1 are used ATP & enzymes break apart CO2 + H2 C’s, O’s, and H’s recombine into C6H12O6 (Glucose)

60 seconds: Discuss with your neighbor #2 #1 reactants products Which reactant(s) are used during the light independent stage? Which product(s) are created during the light independent stage?

Connection between photosynthesis & respiration Plant Cell chloroplast mitochondria glucose ATP chloroplast mitochondria glucose ATP Plants Create glucose through photosynthesis Glucose is used to make ATP through cellular respiration

Connection between photosynthesis & respiration Glucose (from food) mitochondria ATP Glucose Animals Plants create glucose through photosynthesis Animals eat the plants Glucose is used to make ATP through cellular respiration

Review Which color(s) is/are absorbed by a typical red apple? Which color(s) is/are reflected by a typical red apple? Which color light produces the highest rates of photosynthesis? What is used during the light dependent reactions? What created during the light dependent reactions? What is used during the light independent reactions? What created during the light independent reactions? True or False: Plants are the only photosynthetic organisms.