| Explore | From experiences outside of school we know that in order for plants to survive they need water and sunlight. We also know that plants use photosynthesis to make their own food, which means they are autotrophs. However we have discovered many new things about plants in class. For example, we found out that the process of cellular respiration is just as important for plants as photosynthesis. This is because during the process of cellular respiration in plants, the cells use oxygen and glucose to make energy so that they can funciton. Whereas in photosynthesis plants make food, such as sugars, to use as fuel. We have also discovered that during photosynthesis plants release oxygen and during cellular respiration plants release carbon dioxide. Some reasearch question about plants that interest us include "How much food (Sugars) do plants make or need on a daily basis?", "How much oxygen or CO2 do plants release into the atmosphere?", and "What would happen if plants only got sunlight?". These are some of the questions we have about plants and what we have learned in class. |
|---|---|
| Research Question | The research question that we want to study is "What effect(s) do light and dark have on plants?". The reaserch question was developed becuase we wanted to find how plants react in the light or in the dark. This question fits what we know about the topic because we know that in the light photosynthesis takes place, whereas in the dark cellular respiration takes place. So we wanted to see what difference light and dark make on the plants. |
| Predictions | According to my group we all have the same predictions based on the variables we are working with. Since we are working with plants placed in the dark and plant placed in the light, we think that the plants in the light will preform photosynthesis, and plants in the dark will not becuase they will perform cellular respiration. These are our predictions because when photosynthesis happens, oxygen is released and when the plants are placed in the dark, no oxygen is released. This is our explanation for our predictions about our study. |
| Experimental Design | [Procedure- 1.Prepare the solutions for the two cups 1a.Label the 2 cups - one of them "Light" and the other "Dark" 1b.Add distilled water to each cup about halfway (make sure to have the same amount) 1c.To each cup add about a pinch of baking soda and one drop of soap, then stir the mixture(make sure to not stir too much that it creates soap bubbles) 1d.Set the cups to the side and continue with the setup 2. Make the leaf disks 2a.Use the hole puncher to make about 20-25 leaf disks from the spinach leaves 3.Remove the gasses inside the leaf disks and infiltrate them with the solutions prepared in step one 3a.First, remove plunger from the syringe and pour 10 leaf disks into the syringe 3b.Tap the syringe so the leaf disks fall to the narrow end where the needle would go 3c.Carefully push the plunger back into the syringe, make sure to not damage any disks and push almost all the way down 3d.Then place syringe into the solution of the cup labeled "Light", and pull up some of the solution until the syringe is about 5 cm full 3e.Then hold the syringe upwards where the needle side is facing up, and try to push the excess air out-CAREFULLY 3f.Cover the tip of the syringe with your finger and pull the plunger, you will feel a vacuum pulling on your finger tip 3g.Do this a few times until all the leaf disks sink to the bottom of the syringe 3h.Once all the leaf disks sink, take out the plunger and hold the syringe sideways with your finger still covering the tip, and pour the solution back into the cup labeled "Light" 3i.The leaf disks should fall into the cup with the solution, if they don't then pull up some more of the solution and pour it back out so the disks fall into the cup. 4.Repeat the infiltration process (Steps 3a-3i) for the other cup labeled "Dark" 5.Prepare a data table in google sheets like the one attached to this project 6.At the same time place the cup labeled "Light" under the light source(5-10 cm between the cup and light) and the cup labeled "Dark" in a dark cabinet 7.As soon as you put both cups in their spots, start the time for 25 minutes 8. Then record data for both cups on how many leaf disks are floating and how many are not floating in the data table(prepared in step 5) at one-minute intervals 9.After 25 minutes stop collecting data] [Explain Variables-The variables that we will be testing include the Spinach leaf disks and how they react to different settings during the 25 minute time period. The dependent variables that we are measuring and observing are the leaf disks in the solutions. This is because we want to measure the difference between floating disks and not floating disks between the dark and the light. The Variables that we are going to keep constant are the solutions for the two different cups and the time period for both cups in which we will collect the data. For example both cups have a mixture of the same solution, which includes distilled water, baking soda, and a drop of dish soap. Also, the time period for measuring data for each cup will be the same, so for each cup we will measure the same amount of time (25 minutes). The independent variable for this experiment is the setting the cups are placed in. The point of this experiment is to figure out how light and dark affects the leaf disks, so the cup labeled “Light” will be placed under a light source and the cup labeled “Dark” will be placed in a dark cabinet. These are some of the variables that we will be testing in this experiment.] |
| Conclusion | The claim we can make from our experiment is that in the dark photosynthesis doesn't occur, while in the light photosynthesis does occur. The possible explanations for this is that the gas produced during photosynthesis, which is oxygen, helped the leaf disk under the light float, whereas in the dark no photosynthesis occured and oxygen was not produced. So, the leaf disks did not float. The results we collected help explain our reasoning because during the 25-minute period, by the end, all 10 leaf disks under the light had floated, whereas in the dark no leaf disks floated. For example by the 11-minute mark, already all leaf disks had appeared to float that were placed under the light, and the leaf disks in the dark had no change during the 25-minute period. This is because leaf disks placed under the light produce oxygen faster during the process of photosynthesis, which is why the disks floated so quickly. Disks in the dark did not produce oxygen at all becuase they didn't have the vital source for photosynthesis, which is light. So, no leaf disks floated. The future experiment we came up with is placing 1 cup with 10 leaf disks into the light for half of 25 minutes, then placing it in the dark for the rest of the time, this is to find out if there would be any changes if it alternated between the 2 settings. This is our conclusion for our experiment on how light and dark effects plants. |
| Investigation Theme | POS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| Teacher Name | Bill Welch |
| School Name | Campus High School |
| Session | Fall 2023 |
| About this Project | This group did a wonderful job with their experiments. They had excellent descriptions of setup and very strong explanations of results and conclusions. They always answered mentor questions and responded to all communication. -- Mindy Findlater, Liaison |
