Download Photosynthesis - Lemon Bay High School

Photosynthesis
Chapter 8 Lesson 2
Learning Goals
Students will explain the role of light and pigments in
photosynthesis and state the overall equation for
photosynthesis.
Energy production
• Plants use energy of
sunlight to convert water
and carbon dioxide into high
energy sugars and oxygen
(Test question)
Light & Pigments
• In addition to water and carbon dioxide,
photosynthesis requires light and chlorophyll, a
molecule in the chloroplasts.
• Plants gather sun’s energy with light absorbing
molecules called pigments. (test question)
• The plant’s principal pigment is chlorophyll
• 2 types: chlorophyll A and chlorophyll B
Light & Pigments
• Many different types of pigments
• Chlorophyll – reflects green/green yellow
• No. 1 pigment in plants
• Carotenoids – reflects reds, oranges, yellows
• Gives carrots and tomatoes their colors
• Anthocyanins – reflects reds, violets, blues
• Causes leaves to change colors in the fall
• Photosynthesis requires light and chlorophyll
• Chlorophyll absorbs light in the blue-violet and red
regions of the visible spectrum.
• Chlorophyll does not absorb light in the green
region of the spectrum.
This is why plants look
green, they do not absorb, but
reflect green wave length light
(test question)
Chloroplast Structure & Function
• Photosynthesis takes
place in chloroplasts
• Specifically the
thylakoids and stroma
• A stack of thylakoids
are called a granum
Electron Carrier Molecules
• When chlorophyll absorbs light, much of
the energy is transferred directly to
electrons in the chlorophyll molecule,
raising the energy levels of these
electrons.
• These high-energy electrons make
photosynthesis work.
Light Dependent Reactions
• Energy from sunlight is absorbed by chlorophyll
• Takes place in the thylakoids
• Inputs are Sunlight and H20, outputs are O2.
• Converts energy into chemical energy in the form
of electron carrier molecules like ATP & NADPH
Light Independent Reactions
• Light Independent Reactions are known as the
Calvin Cycle (named after a scientist)
• Takes place in the stroma (liquid part of the
chloroplast)
• CO2 + ATP + electrons from NADPH =
Carbohydrate molecules (sugars)
• ATP converts back into ADP & NADPH turns back
into NADP+
Photosynthesis takes place in two steps:
light dependent & light independent reactions
Product of Calvin
cycle is high
energy sugars!!!!
(test question)
Assignment/Exit Slip
What factors affect photosynthesis?
• Read page 240 and answer question 3.a
– Include temperature ranges & what they affect,
how too much light or too little light might damage
a plant, and how too much or not enough water
would affect a plant’s ability to photosynthesize.