Photosynthesis

1. Photosynthesis

2. Photosynthesis

3. The Photosynthesis Equation
6 CO
2
+ 6 H
2
O + sunlight C
6
H
12
O
6
+ 6 O
2
Carbon Dioxide + Water + Light Energy sugar + oxygen
What is it?
•Plants use energy from the sun to convert carbon dioxide and water into
oxygen and sugars.
•Plants use some of the sugar for food. The cells break down the sugar
molecules to release the energy they contain.
Where does it happen?
•In chloroplasts: Some sugar molecules are converted into other
compounds like cellulose. Other sugar molecules may be stored for later
use.
•When you eat food made by plants, like carrots or potatoes, you are
eating the plant's stored energy.
Which organisms use it?
•Plants (land or water) and phytoplankton
What do we call organisms that make their own food?
•Producers or “autotrophs”

4. The Two Stages of Photosynthesis
Stage 1: Capturing the Sun's Energy
What happens in stage 1?
•Chloroplasts are green organelles inside plant
cells.
•The green color comes from pigments, colored
chemical compounds that absorb light.
•The main photosynthetic pigment in chloroplasts
is chlorophyll.
•Chlorophyll captures light energy and uses it to
power the second stage of photosynthesis.

5. The Two Stages of Photosynthesis
Stage 2: Using Energy to Make Food
What happens in stage 2?
•Roots absorb the water and stomata absorbs the carbon dioxide.
•Stomata are small openings in the underside of leaves.
•water and carbon dioxide in the leaves moves into the chloroplasts.
•Chloroplasts use the water and carbon dioxide and with the energy
from the 1st stage, undergo a series of chemical reactions.
•The reactions produce products:
–sugar that has 6 carbon atoms. Sugars are a type of carbohydrate.
Cells can use the energy in sugar to carry out important cell functions.
–oxygen, which leaves the leaf through the stomata.
•Almost all the oxygen in the Earth's atmosphere is produced
through photosynthesis.

6. Cellular Respiration

7. Cellular Respiration
C
6
H
12
O
6
+ 6 O
2
6 CO
2
+ 6 H
2
O + Energy (ATP)
sugar + oxygen Carbon Dioxide + Water + Chemical
Energy
What is it?
•cells use oxygen to release energy stored in
sugars, like glucose
Where does it happen?
•in organelles called mitochondria
Which organisms use it?
•Plant AND animal cells both have mitochondria

8. Two Stages of Cellular Respiration
Stage 1: Happens where? in the Cytoplasm
What happens in stage 1?
•Glucose in the cytoplasm is broken down into
smaller molecules, releasing energy
•Smaller molecules move into the mitochondria

9. Two Stages of Cellular Respiration
Stage 2: Happens where? in the Mitochondria
What happens in stage 2?
•Smaller molecules (glucose break-down products) move into the
mitochondria.
•Oxygen enters the cell & goes into the mitochondria.
•As the smaller molecules are broken down even further, hydrogen is
released in a way that allows cells to capture energy in a usable
form. The hydrogen combines with oxygen to make water.
•Products: energy, carbon dioxide, and water.
•Some of the energy is transferred to other molecules, which carry
the energy where it is needed for the activities of the cell.
•Remaining energy is released as heat.
•Carbon dioxide formed during cellular respiration is released by the
cell.