Download Photosynthesis

Photosynthesis
Learning Target:
I can explain how
photosynthesis
produces cell energy
(ATP)
How much do you already know?
• What does autotroph and heterotroph mean?
• What is photosynthesis (be specific)?
• Where in the plant does photosynthesis
typically take place?
Background info:
• Autotrophs- make their own food
• Heterotrophs- obtain food by eating other
organisms (plant or animals)
What is Photosynthesis?
• the process where autotrophs (plants and other
organisms) use energy from the sunlight to
convert carbon dioxide and water into sugar
(glucose) and oxygen (by-product).
Takes place in the chloroplast of
leaves
How much do you already know?
• What are the different structures of a plant
(related to photosynthesis) and what are their
functions?
• What are the raw materials needed for
photosynthesis and how does the
plant get them?
Other Plant Structures:
Leaf- where PS occurs
Stem- holds the plant upright, carries
water and food throughout the plant
Xylem- carries the water UP to the leaf
Phloem- carries the “food” (sugars)
down to the roots
Roots- anchors the plant into the ground
for support; absorbs water
Raw Materials needed:
• Water
• CO2
• (Sunlight)
How much do you already know?
• What happens in the first stage of
photosynthesis?
Stage 1: Capturing the Sun’s Energy
The sun’s energy is absorbed by
chlorophyll in the chloroplast and used
to make energy molecules called ATP
and NADPH
How much do you already know?
• What happens in the second stage of
photosynthesis?
• What are stomata and where do you typically
find them?
• What happens to the glucose
once it is made?
Stage 2: Producing Sugars
• CO2 enters the bottom side of the leaves
through openings called stomata
• Water is absorbed through the roots and moves
up the xylem to the leaf.
• Inside Chloroplast, the CO2 and water are
chemically rearranged to form sugar (glucose to
store/use) and oxygen (release back out the
stomata).
Stomata
(means opening)
• Typically found on the bottom side of leaf.
• Controls the rate of evaporation for plants
with the help of “guard cells”.
• When the stomata are open, carbon dioxide
can enter and water vapor can leave
(transpiration).
How it works!
• Guard cells change
shape using osmosis.
• To open stomata:
guard cells “swell”
(water enters)
• To close stomata:
guard cells "deflate“
(water leaves)
• How? Active transport pumps potassium ions either in or
out of the guard cells to/from the surrounding cells. Water
will follow where the potassium is pumped because it
changes the concentration gradient due to the higher
concentration of dissolved solutes (potassium in solution).
Storage and growth
• Glucose can either be used for plant growth
and development of the plant or stored.
Review Questions
1. Where does photosynthesis take
place?
2. What do plants need to make food?
3. Where does it (plants) get these raw
materials?
4. What does the plant produce from
these materials?
5. Where do these products go?
6. What is the difference between an
autotroph and a heterotroph?
7. What does the xylem and phloem do
for the plant?
8. Why do you think stomata are typically
found on the underside of leaves?
9. How do stomata regulate evaporation
rates?