Follow the directions given in this lab description Actions and use this Lab Report Template file Actions to record data and answer questions. You will also need this Excel file for

Lab #5: Photosynthesis – Lab Report Template

Name:

Use this form to complete this week’s lab report assignment as directed in the BIOL 100L Lab5 Photosynthesis file. Once complete, the file should be saved as a pdf with the file name that follows this format:

Your full name_BIOL100_Lab5

Part 1: Developing a photosynthesis measurement system

Temperatures (C):	Beginning:	End:	Results and notes: record what factors were changed and any relevant observations
Trial 1:
Trial 2:
Trial 3:

Table 1. Data collected for the development of an effective photosynthesis system for Part 1.

Summary Notes:

Table 2. Summary of your successful photosynthesis system; note specific leaf source, light system, things that you will be carefully monitoring during the actual experimental trials of Part 2, etc.

Part 2: Evaluating carbon as a limiting factor in photosynthesis

Question A: If carbon dioxide concentration is low, would expect the plant cells to not photosynthesize at all or would you expect the rate of photosynthesis to simply slow down? Explain your reasoning.

Question B: In light of your answer to Question A, write an hypothesis that specifically states what you expect to see in plant response (i.e., floating leaf disk rate) to varying levels of added carbon dioxide. Remember that hypotheses are not questions, but rather are declarative statements that are testable and falsifiable.
Trial:	Beginning Temp. (C):	Ending Temp. (C):	Time (min. and sec.) when first leaf disk rises:	Notes: record anything that might be a factor affecting floatation of the disks that were different between trials.
Cup A
Cup B
Cup C
Cup D
Cup E
Cup F

Table 3. Temperature record for photosynthesis trials of Part 2.

Trial:	0 min.	5 min.	7 min.	9 min.	11 min.	13 min.	15 min.	30 min.
Cup A
Cup B
Cup C
Cup D
Cup E
Cup F

Table 4. Number of leaf disk counts at specific times for the photosynthesis trials of Part 2. The leaf counts for time 0 minutes should be 0 if all the leaf disks were properly sunk at the beginning of the trial for that cup.

Photo of Cup “A” at beginning of the trial:

Photo of Cup “A” at end of the trial:

Table 5. Photos of your lab activities.

Table 6. Graph of the leaf count data.

Question C: Is there a correlation between the independent variable and dependent variables? Describe the pattern and interpret its possible meaning.

Question D: Does the data support your hypothesis? Describe what conclusions can be logically made regarding the effect of carbon dioxide concentration on leaf disk photosynthesis.

Question E: How might the experiment be done better with a view to testing your hypothesis? For example, describe some of the controlled variables that could have been kept more constant between trials.

Part 3: Evidence of respiration

Time intervals:	0 min.	3 min.	5 min.	10 min.	20 min.	30 min.
Number of sunk leaf disks:

Table 7. Number of non-buoyant leaf disks at given time intervals for Part 3.

Time when the first leaf disk rises to the surface: _______________
	0 min.	5 min.	7 min.	9 min.	11 min.	13 min.	15 min.	30 min.
Cup F

Table 8. Time of first leaf disk at surface and number of leaf disk counts at specific times for the photosynthesis trials of Part 3. The leaf counts for time 0 minutes should be 0 if all the leaf disks were properly sunk at the beginning of the trial.

Question F: Is the experiment where Cup A is put into a dark chamber (steps 1 and 2) a convincing demonstration of respiration? Review Module 26 of the OLI curriculum and describe what the plant cells are doing with the oxygen molecules that had been trapped in the plant tissues and were causing the leaf disks to float.

Question G: Do a quick internet search to find out what the % concentration is for carbon dioxide in the air and in exhaled breath. Report those numbers and explain why we would expect the leaf disks to float in Cup F after blowing into the cup and putting it under the light even though it didn’t have leaf disks floating previously when put under the light.

Question H: In light of your observations of this part of the lab and the chemical reactions explained in Module 26 of the OLI curriculum, describe how photosynthesis and respiration are tied together.