Biology Lab Abstract, Introduction, discussion, and references.
Abstract: The Musa x basjoo trees are located around Northern Kentucky University campus where it exhibits two variations of leaves – shredded and intact. We found it perplexing that instead of the damaged leaves being replaced they remained on the tree. This led to our question on whether or not the rate of the two metabolic processes (photosynthesis and cellular respiration) were happening at a lower, constant, or higher pace in the damaged leaves compared to the healthy, intact ones. In order to determine the rate of photosynthesis for both leaf variations, we needed to test them each under a lamp to obtain Net primary productivity and in the dark for only cellular respiration. By doing so we would be able to calculate the Gross primary productivity and in turn figure out which leaf variation was effectively capturing the sun’s light. We also tested for light intensity for eight out of twelve of the samples. The results for the rate of photosynthesis and the light sensitivity, showed that the intact leaves had a higher rate for both categories compared to the shredded leaves. To conclude our experiment, we incorporated a statistical paired T test in which resulted in our team failing to reject the null hypothesis due to our p value being greater than 0.05. This means there was no credible difference in photosynthetic rates between the two leaf variations.
Introduction:
Around NKU campus there are Musa X basjoo (banana) trees that had completely intact and damaged/shredded leaves. The underlying causes of these observed variations are caused by the plants having very limited or no protection from environmental factors such as strong winds. Even though the leaves were damaged, they remained on the tree which we found perplexing and unusual. We wondered if this was an adaptation of the plant’s leaves to continue photosynthesizing at some capacity in order to survive.
Photosynthesis is a biochemical process for building carbohydrates using energy from sunlight and carbon dioxide (CO2) taken from the air. These carbohydrates are used both as starting points for the synthesis of other molecules and as a means of storying energy that can be converted into ATP through cellular respiration. (How life works, pg. 154) During cellular respiration, fuel molecules such as glucose, fatty acids, and proteins are catabolized into smaller units, releasing the energy stored in their chemical bonds to power the work of the cell (How life works, pg 132). Photosynthesis and cellular respiration happen at the same time during the day which represents net primary productivity which provides an estimate of how much energy is being harvested from the sun through photosynthesis when both metabolic processes occurring (Lab manual, pg. 47). The total amount of energy captured by the plant through photosynthesis alone is gross primary productivity(Lab manual, pg 47). In order to calculate the gross primary productivity, you must subtract cellular respiration from Net primary productivity.
The name of scientific name of our banana tree is Musa X basjoo and it is native to the Ryuku Islands near Japan. Due to the Musa x basjoo being winter hardy, it is recommended that the plant be moved indoors when temperature drops below around 40 degrees Fahrenheit. It is best grown at a site that is protected from environmental elements, moist soils with good drainage, and in full sunlight. The plant produces large paddle-shaped leaves that can grow from 2’ wide to 6’ long. Even though this plant produces fruit, gardeners tend to purchase and grow these plants for their ornamental foliage or for the plant’s fiber to be used for fabrics. The plant uses carbon to grow and releases oxygen as a bi-product thereby reducing the concentration of CO2 and decreasing the greenhouse effect. The plant continues to do so until the plant burns, dies, and/or breaks down. I believe figuring out if the damaged leaves can photosynthesize at some capacity than the leaves that are not damaged those results could give us insight into why the banana tree plant doesn’t shed them and how we can utilize this to reduce global warming.
Discussion:
The goal of this experiment was to figure out if there was a difference in photosynthetic rates between two variations of leaves. We predicted that there would be no difference in respiratory rates between the two leaf variations, that shredded leaves would have lower rates for gross primary productivity and net primary productivity than the intact leaves. We have two graphs that support our hypothesis that intact leaves have higher photosynthetic rates than shredded leaves. The average rate of gross primary productivity data shown in graph A support our hypothesis by showing that intact leaves have a higher rate of photosynthesis than shredded leaves. The average light intensity rate between the leaf variations in graph B, supports our hypothesis because it shows that no matter the position the leaves were before extraction the rate of light intensity was lower for shredded than intact leaves. What did not support our hypothesis was the statistical paired sample test. Our p value was 0.283589, and our t value was 2.015048. Due to the p value being greater than 0.05, we failed to reject the null hypothesis. This means there is no credible difference between the means of the shredded and intact leaves. If the p value was less than 0.05, we could have rejected the null hypothesis and assume that there was a difference between photosynthetic rates between the two leaf variations. (Lab manual pg. 36)
I’m speculating that the results from the statistical paired t-test could support that the banana tree does in fact have leaf adaptations in order to survive its environment, reproduce, and maintain the health of the plant. I believe that there’s no difference in photosynthetic rates because the leaves were meant to shred in order to prevent the plant from being uprooted during harsh storms. We did encounter some troubles with our experiment such as the extracting samples without the proper equipment to reach the height that the samples were located, we weren’t able to collect all of our samples before the cold temperatures forced staff to move them into a greenhouse and using one lamp with the same type of lightbulb. Due to the plant being moved into a greenhouse, we weren’t able to acquire the light intensity rates for 3 of the samples, the 3 leaf samples came from the same tree, and we aren’t sure how long the plant had been cut laying there. How we could have addressed these problems was to collect all 12 samples on the first day of our lab after we initially collected the data for our eight samples collected. As well as, measuring light sensitivity.