Autotrophic Nutrition

•What 3 things do plants need to survive?
•Think of plants growing in a backyard with big trees.
•What grows under the largest trees? Why?
•Why do plants need sunlight to grow?
•Where does all the water go that a plant absorbs?
•Why don’t plants die at night when the sun goes down?
•Why are plants called autotrophs, or producers?
•What is the process that a plant uses to make food?
•How does this food making process occur?
• is the most common form of
autotrophic nutrition
• is making glucose (food) using light…
• in other words, converting light energy
into the chemical energy of food
• Photosynthesis is very important for 2
reasons. It provides
1. Most of the food for everything on Earth.
2. Most of the O2 for everything on Earth.
• Plants and algae perform photosynthesis to
make food for themselves, NOT FOR US!
• The oxygen they release is bonus!
How Its Done
• Photosynthesis takes place in chloroplasts, which are
cell organelles found in algae and plant cells.
• Inside the chloroplasts are special pigments called
chlorophyll which absorb light for photosynthesis.
• Chlorophyll is green.
• Chlorophyll absorbs wavelengths (colors) of red and
blue most effectively.
On your diagram, do the following:
• Color the chloroplasts green.
• Label “w” as chloroplasts.
• Show green arrows bouncing off chloroplasts toward a human
• Show blue and red arrows being absorbed by chloroplasts.
House Construction Analogy
• Raw materials for building a house include lumber
and nails and shingles.
• The energy comes from the carpenter and electricity.
• The final product is the house.
• The waste products are sawdust and scrap wood.
• Sawdust and scrap wood may be recycled or used
for some other purpose.
• Now compare photosynthesis to the
house construction analogy…
• Ingredients for photosynthesis include:
1. sunlight
2. carbon dioxide (an inorganic cmpnd)
3. water (an inorganic cmpnd)
• Mix the 3 ingredients in the chloroplasts and
you get…
1. glucose (C6H12O6) which is a simple
sugar. This is food.
2. oxygen (O2)
Chemical Equation for Photosynthesis
6 CO2 + 12 H2O
C6H12O6 + 6 H2O + 6 O2
Word Equation
carbon dioxide + water = glucose + water + oxygen
The atoms of carbon, hydrogen, and oxygen are
rearranged to form glucose and oxygen. This
rearrangement requires POWER in the form of light
What Happens to the Glucose
1. It is broken down further by cellular
respiration to obtain ATP (Yes – plants
need ATP, every living thing does!)
2. It is synthesized into other molecules like
starch (storage).
Chunk Time!
Define autotrophic nutrition.
Name two types of autotrophs.
Where does photosynthesis occur?
What 2 things does photosynthesis provide to life forms on
Why do plants carry out photosynthesis?
What is the pigment in the chloroplasts, and what color is it?
What colors are best absorbed by chlorophyll?
Name 3 ingredients for photosynthesis.
Name 3 products of photosynthesis.
What is the chemical equation, and the word equation?
What are 2 things that can happen to the glucose produced?
Just for Fun!
• Explain the biology behind these cartoons.
Weird but True!
Perhaps you think
you've seen it all but
have you seen the
plant that can
actually walk? The
walking palm is a
palm tree native to
the rainforests of
central and South
America. Its stilt like
roots enable it to
walk, towards the
sun at a rate of 1
meter per year.
Image Sources
Flow chart -
Absorption spectrum -
Cell diagram -
Cartoons -
Walking plant -

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