1Factors that affect the rate of photosynthesis write



Factors that affect the rate of photosynthesis write-up rubric /100 lab pts.

Format: (20 pts)

12 pt font (1): ______

Double spaced (1): ______

1 inch margins (1): _____

Typed (1): ______

Name at top (1): ______

Bold title (1): _______

Informative title (1) _______

Bold title for introduction (1) : ______

Procedures (5)

A numbered list (1) ____

Includes the essential steps of the experiment (2)


Does not include unnecessary details (e.g. collected materials, wrote down results.) (1) ___

Inclusion of details that impacted your results (e.g. distance from light, how variables were controlled)

(1) ____

Bold title for Hypothesis (1) : ______

Bold title for Materials (1) : ______

Bold title for Procedures (1) : ______

Results as graph (1) ____

Bold title for conclusion (1): ____

All titles spelled out (1): _____

All lab papers stapled to the back (3) ___

Clearly written with concise statement (2): ___

No excessive spacing between heading and title

Results: correctly determine how many lines are needed on graph

Graph: (7)

Correct graph bar/ line (2): ________

Axis labeled (1): ______

Informative title (1): ______

Y axis units: tabs/min (1): _______

X axis independent variable (1): ______


Hypothesis (3)

States as an if… then statement(1) ___

“then” a change in rate of tab movement(1): ___

Testable by experiment(1): ____

Scaled appropriately (1) ____

(if your experiment did not produce results graph the results of the pre-lab)

Introduction (30)

Light is needed for photosynthesis (2): ___

That water and CO


are reactants (2): ____

Oxygen gas is a product (2): ____


How photosynthesis relates to the design of the experiment (3): ___

Conclusion (30):

This will vary depending upon the variable/ factor you chose to test. The key is that you show you understand the principles behind the experiment and the logic of your conclusion is clearly outlined.


If your experiment worked:

Results are clearly explained in terms of the

The production of O


makes the spinach taps less dense so they rise to the surface (3): ___

Results are measured by how many taps float to the top per min. (2): ____

The dependent variable is the rate (2): ____

The independent variables are light intensity, temperature of water, color of light, and concentration of CO


(3): _____

The factor tested in experiment (3): ___


. How your experimental design relates to your hypothesis (3): ____


Any concepts that relate to the variable you manipulated (e.g. pigments, light, reaction rates)


Materials (5)


Bullet pointed list of essential materials. __ concepts covered in the introduction.

Explanation refers to the variables your group tested

(25). ______

Discussion of possible experimental error(5) __


If your experiment did not work:

Discussion of possible experimental error.

(10) ____

Explanation of what you think went wrong and what you would change if you could do the experiment over again. (20) ____






Students designed experiment to test the affect of one of the following on the rate of photosynthesis: the level of CO

2 in solution, the intensity of light, the color of light (visible colors & UV), and temperature.

Students were graded on their demonstration of knowledge of both photosynthesis and the scientific method.

Clearly explains how the variable they manipulated relates to the process of photosynthesis i.e. “light is the energy that plants use to run the reaction of photosynthesis, thus changing light levels should impact the rate of photosynthesis.”

Ex: Our hypothesis was that if blue and red light were block from reaching the plant then the taps would rise more slowly to the top of the solution. We tested this by placing both blue and red film over the cups containing the solution with the spinach tabs.

This will vary based upon the factor tested. The test of CO


levels should have mentioned that CO


and water are both reactants and that by increasing the reactants in a chemical equation should speed the reaction up to a point. That the increase in rate will be limited by the plant’s enzyme; plants use enzymes for reactions and that if the number of reactants exceeds the capacity of the enzymes then the reaction can not be accelerated. The test of temperature should mention that as molecules are heated they move faster, thus increasing the rate of chemical reactions, however in enzymes are heated too much they will denature and become non-functional. The test of color should mention that plants use pigments to absorb light and that each pigment only absorbs light of certain wavelengths. The most common pigment being chlorophyll A which absorber mostly blue and some red light. Finally, light intensity, light is the energy source that plants use to run the reaction, so the more light more energy.

The conclusion must discuss possible experimental error even if the students thought the lab ran perfectly. They also needed to EXPLAIN their results, not just relate them. Why did the rates increase or decrease, how does that fit with what we know about photosynthesis. Was the hypothesis accepted or rejected. What could have been done differently to insure the results were due to the factor tested? For example, student found that the samples closest to the light reacted slower than the ones farther away.

Many surmised that this was due to the heat of the incandescent light. A way to test this would be to use

LED light that do not produce as much heat but do produce light to distinguish the affect of light intensity from heat.