Topic :
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The Introduction of Biology
Defining of life
Basic chemistry, the chemistry of organic molecules
Classification of living things
History of cells and Cells structures and functions
• Photosynthesis and cellular respirations
• Darwin evolutions
• Ecosystem and human interferences
LO’s
1. Explain why photosynthesis is so important to energy and
material flow for life on earth
2. Understand that photosynthesis is a two fold process
composed of the light-dependent reactions (i.e., light
reactions) and the light independent reactions
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
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
Carbon
dioxide
Water
Glucose
PHOTOSYNTHESIS
Oxygen
gas
WHY ARE PLANTS GREEN?
Plant Cells
have Green
Chloroplasts
The thylakoid
membrane of the
chloroplast is
impregnated with
photosynthetic
pigments (i.e.,
chlorophylls,
carotenoids).
Sunlight
• Electromagnetic energy (radiation)
• Packets of energy (photons)
• Range of wavelengths
The feathers of male cardinals are
loaded with carotenoid pigments.
These pigments absorb some
wavelengths of light and reflect
others.
Sunlight minus absorbed
wavelengths or colors equals
the apparent color of an
object.
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
Heterotrophs
• Consume other organisms
• Cannot produce their own food
• Food ultimately comes from autotrophs
Photosynthesis occurs in chloroplast
Two stages of Photosynthesis :
1. Light reaction ( with a solar energy captured and transformed
into chemical energy
2. Calvin cycle – the chemical energy is used to make organic
molecules
AN OVERVIEW OF PHOTOSYNTHESIS
• The light reactions
convert solar energy
to chemical energy
Light
Chloroplast
– Produce ATP & NADPH
• 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
NADP
ADP
+P
Light
reactions
Calvin
cycle
CO2 and water are
waste products of
cellular respiration
Oxygen – used for cellular
respiration