Writing in Biology

Sieve tube elements and sieve plates are two completely different elements in a plant, despite the similar names. Sieve tube elements are components that form end to end to create sieve tubes, while sieve plates form between the sieve tubes. The sieve plate has micropores in it that connect the adjacent sieve tubes, allowing for material exchange between each tube. Normally this would pose a risk to the plant because one damaged sieve tube would cause the whole plant to “bleed out” as all of the water and nutrients it was transporting would be lost. To combat this, the plant can detect when the sieve tube is damaged and secrete callose, which can seal the pores in the sieve plate to stop nutrient and water transfer in that tube. This process acts much like coagulation in the human body.

There are three main phases of the Calvin cycle: carbon fixation, reduction, and regeneration. During carbon fixation, a CO2 molecule combines with a RuBP molecule. This forms 3-PGA, which is catalyzed by rubisco. Reduction is the second stage in which ATP and NADPH are used to convert the 3-PGA into G3P. This is because the NADPH donates electrons to the 3-PGA to reduce it to G3P. Finally, during regeneration, some of the G3P molecules are used to make glucose, while the others are recycled to regenerate the RuBP acceptor. This process requires ATP and involves a complex network of reactions. This allows the cycle to start over again and continue on. 

Global warming is a major concern for modern day society. As global temperatures rise, the glacial caps melt and species of plants and animals adapted to a specific climate are put at risk of extinction. A major contributing factor to this global warming is a process called the greenhouse effect. As human activity increases, so does the global CO2 levels. CO2 is a heavy gas, meaning that it will pass visible light, while reflecting infrared light. This causes the CO2 in the atmosphere to build and retain heat. The rapid increase in CO2 levels is one of the major causes of the increase in the global temperature.

Plants exhibit both primary growth, as well as secondary growth. For primary growth the plant elongates, growing out of the soil and towards the sun. This type of growth is fairly rapid in order to maximize photosynthetic output. Secondary growth is when the plant widens. In order to do this, the plant requires a layer of tissue called the vascular cambium. The vascular cambium is between the interior xylem and exterior phloem. This growth forms layers of secondary vascular tissue that keep the phloem and xylem in the correct place. These rings can be counted to determine the age of the plant. 

Plants transfer water and nutrients in the plant through the phloem, which is composed of sieve tube elements and sieve plates. If the sieve tube element is damaged the plant is at risk of losing all of the nutrients and water flowing through this. To combat this the plant secretes callose, which blocks the pores in the sieve plate and stops flow through the damaged sieve tube. This has made studying the phloem of a plant particularly difficult. Interestingly enough, and insect breed called aphids have evolved to be able to penetrate the sieve tube without triggering the secretion of callose. By blasting the aphid from the plant while leaving its extractor in place, we have been able to study the phloem of the plant in more depth than ever before. 

Sieve tube elements and sieve plates are two completely different elements in a plant, despite the similar names. Sieve tube elements are components that form end to end to create sieve tubes, while sieve plates form between the sieve tubes. The sieve plate has micropores in it that connect the adjacent sieve tubes, allowing for material exchange between each tube. Normally this would pose a risk to the plant because one damaged sieve tube would cause the whole plant to “bleed out” as all of the water and nutrients it was transporting would be lost. To combat this, the plant can detect when the sieve tube is damaged and secrete callose, which can seal the pores in the sieve plate to stop nutrient and water transfer in that tube. This process acts much like coagulation in the human body.

 Leaves usually display a uniform color across the whole leaf. The pigmentation of the leaf is caused by the chlorophyll. The chlorophyll is what absorbs the light energy for photosynthesis. As can be seen by the leaf, the pigmentation is found throughout the leaf, covering as much area as possible. This is due to the sieve effect. The higher the concentration of pigmentation, the more light that is absorbed. However, if the leaf concentrates more pigment into one area, it lowers pigmentation in another area. By lowering pigmentation elsewhere, the leaf actually absorbs less light than if it had a uniform concentration throughout. This is why leaves are a consistent color across the whole leaf. 

Differences in vesicle movement across treatment and control groups in LLC-Pk1 cells can be explained by nocodazole’s depolymerizing effect on tubulin structure. In the control group, the integrity of the microtubule structure remained intact, enabling vesicles to bind their receptors to microtubule tracks. This then allowed for motor proteins to hydrolyze ATP, producing movement across the microtubule. Though much of this movement is similar in displacement, the data indicates an outlier. This outlier however was still chosen to be presented to exemplify the jerky nature of endosome saltation movement across microtubules, due to occasional detachments of endosome to microtubule. Nocodazole treated cells exhibited low average displacement of vesicles due to the depolymerization of tubulin, which did not allow receptors on the vesicle surface to bind and travel across tubulin structures. Because of this, endosomes remained suspended in the luminal space of the cell, slowly migrating to lysosomes in the interior to be degraded.

Conversely, another article titled, “Effects of trampling and vegetation removal on species diversity and micro‐environment under different shade conditions” provides some insight about plant variation in areas with contrasting light and foot traffic. In the abstract, they write how areas where there was no stress had little variation. Likewise, when there was a lot of stress, the lack of water from excess sunlight and trampling resulted in one stress tolerant species dominating the other plants. However, in a shady area, the availability of water allowed for multiple species to coexist and variation was higher.

There are resources online involving studies that have used some of the variables that we are proposing. One example of these resources is, “Stability in the plant communities of the Park Grass Experiment: the relationships between species richness, soil pH and biomass variability.” In this paper, they found that variation in an area had a negative relationship with biomass. They did not explain exactly why this was the case, but they proposed that time and soil pH may have also had an effect on the variation. In the abstract, they describe how areas with low acidity have more variation because that causes a stress on the species that are rooted in the soil.