LO

1
(No Transcript)
2

• LOs
• Explain why photosynthesis is so important to
  energy and material flow for life on earth
• Know why plants tend to be green in appearance
• Understand that photosynthesis is a two fold
  process composed of the light-dependent reactions
  (i.e., light reactions) and the light independent
  reactions

3
Basic questions??

• What do plants eat?
• Why do plants need light?
• Why do plants need water?
• Why are plants green?

4
Photosynthesis

• Process that captures energy from the sun
• Energy stored in carbohydrates
• Oxygen is byproduct

5
Photosynthesis

• Almost all plants are photosynthetic autotrophs,
  as are some bacteria and protists

• Autotrophs generate their own organic matter
  through photosynthesis
• Sunlight energy is transformed to energy stored
  in the form of chemical bonds

6
AN OVERVIEW OF PHOTOSYNTHESIS

• Photosynthesis is the process by which
  autotrophic organisms use light energy to make
  sugar and oxygen gas from carbon dioxide and
  water

Carbondioxide
Water
Glucose
Oxygengas
PHOTOSYNTHESIS
7
CO2 and water are waste products of cellular
respiration
Oxygen used for cellular respiration
8
WHY ARE PLANTS GREEN?
Plant Cells have Green Chloroplasts
The thylakoid membrane of the chloroplast is
impregnated with photosynthetic pigments (i.e.,
chlorophylls, carotenoids).
9
Sunlight

• Electromagnetic energy (radiation)
• Packets of energy (photons)
• Range of wavelengths

10
Plant Pigments

• Found in chloroplasts
• Absorb some visible wavelengths

11
Plant Pigments

• Carotenoids absorb photons of green,
• blue violet wavelengths
• Chlorophylls absorb photons of red
• violet-blue wavelengths

12
The feathers of male cardinals are loaded with
carotenoid pigments. These pigments absorb some
wavelengths of light and reflect others.
Reflected light
Sunlight minus absorbed wavelengths or colors
equals the apparent color of an object.
13
Why are plants green?
Reflected light
Transmitted light
14
Energy needs of life All life needs a constant
input of energy 1. Heterotrophs (Animals) Get
energy from eating others Make energy through
respiration

• 2. Autotrophs self-feeder (Plants)
• Produce their own energy
• Convert energy of suclight -- chemical energy
• Make energy and synthesise sugars through
  PHOTOSYNTESIS

15
Photosynthetic Autotrophs

• Solar energy powers glucose synthesis
• Uses
• Carbon dioxide
• Water
• Captured energy
• Produces
• Glucose
• Oxygen

16
(No Transcript)
17
Heterotrophs

• Consume other organisms
• Cannot produce their own food
• Food ultimately comes from autotrophs

18

• Photosynthesis looks and sounds like a complex
  process
• Two stages of Photosynthesis
• Light reaction ( with a solar energy captured and
  transformed into chemical energy
• Calvin cycle the chemical energy is used to
  make organic molecules

19

• The location and structure of chloroplasts

Chloroplast
LEAF CROSS SECTION
MESOPHYLL CELL
LEAF
Mesophyll
Intermembrane space
CHLOROPLAST
Outer membrane
Granum
Innermembrane
Stroma
Grana
Thylakoidcompartment
Stroma
Thylakoid
20
Photosynthesis occurs in chloroplast
21
(No Transcript)
22
(No Transcript)
23

• LIGHT ENERGY WATER
• Light energy is used to split water molecules
  known as Photolysis chemical is broken down by
  photons
• ATP is produced during photolysis
• ATP and H ions will be used to fix CO2 to make
  organic molecules
• Photosynthesis relies on water and sunlight
  for its initial reaction

24
(No Transcript)
25
AN OVERVIEW OF PHOTOSYNTHESIS

• The light reactions convert solar energy to
  chemical energy
• Produce ATP NADPH

Light
Chloroplast
NADP?
ADP P
Calvin cycle

• The Calvin cycle makes sugar from carbon dioxide
• ATP generated by the light reactions provides the
  energy for sugar synthesis
• The NADPH produced by the light reactions
  provides the electrons for the reduction of
  carbon dioxide to glucose

Light reactions
26
Plants and animals need each other to survive.