Photosynthesis Dry Lab

Photosynthesis Dry Lab

In this “dry lab” you will be working backwards from what you would normally do in a lab situation. In this case, you will be given a set of observations that were made in a lab and you will be asked to reconstruct the procedure that could have generated this data. You will also be given a set of facts that you will use to explain this set of observations in the analysis and conclusions section of your lab write-up. As you create the procedure for this lab, please remember all the rules that you have been learning about good experimental design.

Your lab report begins below. Fill in the missing sections of the lab report using the observations and facts given. You may assume that you have access to as many test tubes, snails, Elodea plants, light sources, dark places, and as much pond water and BTB as you need.

Make your own copy of this Google Doc and edit the lab report that begins here:

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My Most Awesomest Photosynthesis Lab Report

by

Kelsey Nolte

Purpose: To understand the ways of photosynthesis.

Background Facts:

• Carbon dioxide in water produces carbonic acid.
• Bromothymol Blue (BTB) is a blue-green liquid which changes to a yellow color in acid and back to blue-green when returned to a neutral pH.
• Carbon dioxide plus water yields sugar and oxygen when chlorophyll and sunlight are present.
• Animals respire.
• Green plants photosynthesize in the light and respire all the time.
• Sugar plus oxygen yields carbon dioxide plus water and energy.

Hypothesis:
My hypothesis is that if i was to put a snail into BTB the water will turn yellow because the snail is respiring. Also if we were to put  Elodea into BTB the water will still be blue-green because there is no mix of of carbon dioxide to made carbonic acid.

Materials:
Test tubes, Snails, Elodea plants, Light sources, A dark place, Abundance of pond water and BTB



Procedure:

1. Fill the 5 test tubes with 100 mL of water then add 5 mL of BTB
2. Label the first test tube 1, the sencond 2, the third 3, and the forth 4, and the fith 5
3. Leave test tube 1 untouched
4. Observe and record what happenes
5. Place a snail in test tube 2
6. Oberve and record what happens
7. Place a Elodea plant into testtube 3 and observe what happens
8. In testtube 4 place a snail and the Elodea plant in the dark for 3 hours
9. Observe and record what happenes
10. In test tube 5 place a snail an the Elodea plant in the light for 3 hours
11. Observe and record what happenes
    
    Observations:
    
12. Water plus bromothymol blue is blue-green.
13. Water plus bromothymol blue plus an aquarium snail turns yellow.
14. Water plus bromothymol blue plus Elodea (an aquarium plant) is blue-green in light.
15. Water plus bromothymol blue plus a snail plus Elodea is blue-green in light and yellow when left in the dark for three hours.

Analysis and Conclusions:

1. Water plus bromothymol blue is blue-green because...

This is because the BTB diffused into the water turning it blue-green.

2. Water plus bromothymol blue plus an aquarium snail turns yellow because...

There is oxygen or the snail is respiring (CO2) which turn into carbonic acid when mixed with water. Which changes the pH of the BTB causing the water to turn yellow.

3. Water plus bromothymol blue plus Elodea (an aquarium plant) is blue-green in light because...

This only gives off oxygen and sugar and it is not changing the BTB color because there is no CO2 given off.

4. Water plus bromothymol blue plus a snail plus Elodea is blue-green in light and yellow when left in the dark for three hours...

This is because when the plant in the dark the plant is not photosynthesizing. When there is no sun the plant will not get energy and will give off CO2 (carbon) and there will be carbonic acid to change the pH that changes  the water yellow. So the plant can have the process of photosynthesis if there is sunlight that will cause the water to change color.