NAME:_________________________DATE:_____________________PERIOD:_____
The Relationship Between Photosynthesis and Respiration
Plants are autotrophs or producers. During photosynthesis, carbon dioxide, water and
sunlight are converted into glucose and oxygen. The glucose and oxygen is used by
consumers, or heterotrophs, for respiration. Glucose and oxygen are turned into
carbon dioxide, water and energy. The products of respiration are again used by
autotrophs for photosynthesis. This cycle is continuous, so plants and animals are
dependent on each other.
You will show the dependence of producers and consumers upon each other, by
creating a freshwater ecosystem and observing it over seven days. The presence of
carbon dioxide will be shown with bromothymol blue. It turns from blue to yellow in
the presence of carbon dioxide.
Materials:
Goggles
gloves
3 small covered beakers or jars
pond water
2 freshwater snails
4 Elodea cuttings
lamp
4 drops of bromothymol blue per beaker
Procedures:
1. You must wear goggles and gloves. Bromothymol blue is toxic and will stain
skin and clothing!
2. Add four drops of bromothymol blue to each beaker or jar.
3. Jar 1 gets 2 water plants and 1 snail.
4. Jar 2 gets 1 snail.
5. Jar 3 gets 2 water plants.
6. Seal the containers.
7. Place them the same distance from a lamp.
8. Fill in the Day 1 row on the data sheet.
9. Answer Questions 1 and 2.
Day
1
2
3
4
5
6
7
Jar 1
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Jar 2
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Jar 3
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Color:
What is alive?
What is dead?
Question:
1. What do you predict the color of each jar to be after 24 hours? Why?
(Bromothymol blue stays blue when there is no carbon dioxide present. It
turns yellow when carbon dioxide is present.)
2. What does the lamp represent?
Conclusion:
1. What did you notice about Jar 1 after 7 days?
2. Why did this happen?
3. What did you notice about Jar 2 after 7 days?
4. Why did this happen?
5. What did you notice about Jar 3 after 7 days?
6. Why did this happen?
7. What would have happened if the jars had been in the dark for 7 days?
Why?
8. Could plants exist without animals? Could animals exist without plants?
Why or why not?