1. Snails + Water Weeds

2. Snails Ivory and blue mystery bulb snails Apple Snails
Family Ampullariidae
Genus Pomacea
These Ampullariidae have both a gill and a lung

3. Snails use photosynthesis or respiration?

4. Water Weeds - Wisteria Hygrophila difformis Aquarium plant
Uses photosynthesis

5. Lab Setup 8 airtight containers 4 under a light 4 in the dark Bottle #
Contents
1, 5
Sprig of Hygrophila difformis
2, 6
Snail
3, 7
& Snail
4, 8
Nothing – Control

6. Water + Bromothymol Blue

7. WDYT? What do you think? What is going on in each container?
Why are we putting 4 containers in the dark and 4 in the light?
Why bromothymol blue?
What does this do?
Why should we have a control?

8. Initial Observation What color is the water?
Will there be a change in what the liquid looks like after a couple of hours?
What gas exchange is occurring?

9. Get into your groups
Discuss your initial observations
Designate a speaker to talk about your group’s initial observations

10. Info that may change your mind…
Carbon dioxide dissolves in (and reacts with) water, forming carbonic acid, H2CO3
CO2(g) + H2O(l) ←→ H2CO3 ←→ H+(aq) + HCO3–(aq)
The free hydrogen ions (H+) lower the pH of the solution, making it more acidic.
As CO2 dissolves in water, the pH of the solution will continue to decrease (becoming acidic). If CO2 is removed from the solution, the pH will increase (becoming more basic)

11. Bromothymol blue
A pH indicator such as BTB can therefore indicate the relative amount of CO2 dissolved in water based on the color of the solution.
Higher pH: Blue, basic
Lower pH: Yellow, acidic

12. Photosynthesis is Occurring
6CO2 + 12H2O 𝐿𝑖𝑔ℎ𝑡 C6H12O6 + 6H2O + 6O2
Plant exposed to light
Removes CO2 form the solution
Raises the pH (more basic)

13. Cellular Respiration is Occurring
C6H12O6 + 6H2O + 6O2⎯⎯⎯→ 6CO2 + 12H2O + energy
Snail respires with or without light
Do plants have mitochondria? Can they respire? Look at Bottle 5.

14. Do plants have mitochondria? Can they respire? Look at Bottle 5.
Yellow  Indicating acidic solution
CO2(g) + H2O(l) ←→ H2CO3 ←→ H+(aq) + HCO3–(aq)
Where did the CO2 come from?

15. Where did the CO2 come from in Bottle 5?
The CO2 was produced as a result of cellular respiration by the plant.
Both cellular respiration and photosynthesis occur in green plants when light is available.
In Bottle 1, photosynthesis is the dominant process over respiration, resulting in a net decrease in CO2
HOWEVER, in the absence of light, the plant cannot photosynthesize; it can only respire
THEREFORE, there is a net increase in CO2 concentration and the pH drops as the CO2 dissolves, producing carbonic acid.

17. Bottle
Contents P CR 1
Plant 5 2
P & S 6 3
Snail 7 4
Control 8

18. Revised Observation w/Light BTB color What happened? w/o light 1 Plant
Contents
BTB color
What happened?
w/o light 1
Plant 5 2
P & S 6 3
Snail 7 4
Control 8

19. WDYT - now
Write a paragraph explaining what has occurred in the containers.
Include information about the addition of hydrogen ions or the removal of CO2
What is an ecosystem?
What is sustainability