Photosynthesis Worksheet - Completely Virtual Spring 2021-1 PDF

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Leaf structure and function and photosynthesis experiments BIOL 2140L General Biology Lab

Learning objectives 1) Review the process of photosynthesis 2) Review leaf structure and function 3) Design experiments to study the process of photosynthesis

Activity 1: Structure and function of stomata 1. Using online resources, in your own words describe the structure and function of stomata (4 pts):

Please watch this video that describes how you could measure stomata on a leaf. https://www.youtube.com/watch?v=XcLhuLONQZg (2 pts each blank) 2. This procedure was used on one leaf to produce the three images below. Count the number of stomata in each field of view. Then calculate the average number of stomata. Record all numbers on this worksheet:

Activity 2: How does light intensity affect photosynthesis? Before completing the online activity, answer the questions below. 1. Plants perform both photosynthesis and cellular respiration. For this lab we will look at aquatic plants a) How will photosynthesis occurring in aquatic plants affect oxygen levels in the water? Explain what part of photosynthesis (Calvin cycle or the light dependent reactions) is involved in this change in oxygen levels. (4 pts)

b) How will cellular respiration occurring in aquatic plants affect oxygen levels in the water? (4 pts)

Experimental Question: How does light intensity affect oxygen production? Procedure: 1. Write your prediction based on the experimental question above: (4 pts)

2. Go to: https://www.biologysimulations.com/cell-energy-sim. Set the fish number to 0 and the plant number to 5. Leave the other variables at the default values (25 degrees, white light). 3. Set the light intensity to 100%. 4. Record the starting and ending oxygen values. 5. Repeat steps 3 and 4 for 80%, 60%, 40%, and 20%. 6. Calculate and record the DO difference, in the complete data table. COMPLETE DATA TABLE (6 pts) Light Intensity (%)

DO Start (mg/L)

DO end (mg/L)

DO Difference (mg/L)

100

7

9

2

80

7

8

1

60

7

7

0

40

7

6

-1

20

7

6

-1

7. Make a graph (scatterplot) displaying how light intensity affects changes in DO (DO difference). Correctly label the axes, including units, and provide a figure caption. As a reminder your dependent variable should be in the y-axis and your independent variable should be in the x-axis. Make sure you think about the experimental design and determine what your dependent and independent variables are. You can use excel, google sheets, or hand draw your graph. To receive full credit: 1) all data of DO difference should be included on the graph 4pts, 2) your axes must be labeled correctly and must include appropriate units 4pts and 3) you must provide a figure legend/caption that provides enough information so that someone who hasn’t completed this lab can understand the data 4pts. For details on how to write a good legend look HERE.

8. Write a 3-4 sentence paragraph explaining your conclusion in terms of the process of photosynthesis. Explain how your findings relate to BOTH the light-dependent and light-independent reactions of photosynthesis. (6 pts)

Activity 3: Create your own experiment You will be examining photosynthesis in an aquatic plant using dissolved oxygen. Go back to the simuation and set the fish number to 0 and the plant number to 5. The simulation can test the following variables: light color or temperature. Select one of these as your independent variable. Note: you do not have to look at every option possible. For example, you could just compare two different groups if you wanted. 1. State your hypothesis and one prediction you will test below. Not sure of the difference between a hypothesis and prediction? Check out this website here. (9 pts):

2. Write your procedure below describing how you will test your selected variable (4 pts). What is your dependent variable? (4 pts)

Perform your experiment using the simulator and input your data below. Label the first column, and add more rows if needed. Note, if you are only comparing two treatments, you should consider increasing your sample size (i.e., running the simulation more than one time for each treatment). (6 pts) DATA TABLE Light Color(10-60 minutes)

DO Start (mg/L)

DO end (mg/L)

DO Difference (mg/L)

White

7

9

2

Violet

7

7.5

0.5

Blue

7

7.5

0.5

Green

7

6

-1

Yellow

7

6

-1

Orange

7

7

0

Red

7

7.3

0.3

3. Make a graph displaying your results. Correctly label the axes, including units, and provide a figure caption. As a reminder your dependent variable should be in the y-axis and your independent variable should be in the x-axis. Make sure you think about the experimental design and determine what your dependent and independent variables are. You can use excel, google sheets, or hand draw your graph. To receive full credit: 1) all data points must be present 4pts, 2) your axes must be labeled correctly and must include appropriate units 4pts and 3) you must provide a figure legend/caption that provides enough information so that someone who hasn’t completed this lab can understand the data 4pts. For details on how to write a good legend look HERE.

4. Explain what happened in the experiment and explain why it happened. Did your results support your hypothesis, why or why not? (4 pts)

5. Below, write a sentence or two that describes your results in the format of what you would see in a results section of a scientific paper. Make sure you use the appropriate format to reference your figure (Help here). (4 pts)

Part 4: Thought question. Run the simulation below.

# Fish = 0 # Plants = 5 Light Intensity 20 Temperature 25 Light Color = White 1. Explain what happened to the dissolved oxygen over the course of 60 minutes. Why did this happen? In other words, what process caused the change that you see in DO? (4 pts)

Part 5: Real World Application. Let’s say you have just been hired by a biotechnology company that develops herbicides that are used to kill invasive plants. Before you start, you must research current herbicides and determine how exactly they kill the plants. 1. Choose an herbicide from the list and describe how it kills the plants it is used on. Each of the herbicides disrupt photosynthesis, explain which part of photosynthesis the herbicide disrupts and how it does so. Herbicides to choose from: Atrazine, Clomazone, Paraquat. (5 pts)...