Investigating the Behavior of Leaf Discs, Lab Report Example

Introduction

The photosensitivity of the spinach leaves (Spinachia), had been reviewed with regards to the creation of oxygen as a byproduct. The studies have demonstrated that the creation of oxygen by the plant leaves only requires between one millisecond and five milliseconds. The fast oxygen emission correlates with the composition of the leaf. The thermal qualities of the environment had been demonstrated to have an effect on the oxygen emission index. Oxygen has been demonstrated to be one of the primary gases that are emitted from plants.

The oxygen emission occurs in a variety of plant species that have no correlation with one another. The oxygen emissions appear to occur the most in the tree species that produce wood. Research has monitored the daily tendencies of plants regarding oxygen emissions regarding the correlated contribution of the plant species to the chemical processes in the atmosphere.  There have also been studies connected to the emission of oxygen and the pathways of photosynthesis and photorespiration. The production of oxygen has been correlated with the plant production of glycol ate which is reliant on the characteristics of temperature and light.

Notwithstanding, the majority of the studies that have taken place have applied leaf tissues that have been excised in order to research inhibitor studies of the correlations between photorespiration and oxygen emission. These studies have been restricted in correlating the index of oxygen emission to the component procedures of photosynthesis and photorespiration due to the unknown specificity of the inhibitors. Studies have also applied individual plant leaves in order to review the correlation between CO₂ and light dependence. It had been reviewed that mitochondrial respiration is incorporated in the production of oxygen and that certain qualities of oxygen development are associated with the transport system of the photosynthetic electrons in plants.

Background Information

When luminescence is absorbed by the leaf discs that include chlorophyll a or chlorophyll b, the electrons that are contained within each of the systems of photosynthesis are elevated to the subsequent energy level. The leaves develop ATP which is applied in order to decompose NADP to NADPH. In addition, the leaf discs use the carbon dioxide molecules to convert the carbon into organic molecules. This is delineated as organic fixation. As the leaf discs are placed in the solution and experience the reaction that is reliant on the intensity of the luminescence, oxygen is developed and liberated into the inside of the syringe. The effect causes the leaf discs to rise. Notwithstanding, cellular respiration is also taking place, which causes a consumption of the oxygen that is developed during photosynthesis. The leaves have the requisite of a carbon source in order to perpetuate the processes of photosynthesis. The quantity of light that is received by each leaf disc in addition to the quantity of carbon dioxide that is available will affect the indexes at which the photosynthesis takes place. The goal of the experiment   is to assess the influence of the light intensity and the accessibility of carbon including the influences on the index of photosynthesis.

Hypothesis

In the event that the leaf reacts to the higher intensity light with the availability of a carbon source, it should require less time for the leaf discs to rise to the surface of the syringe as an outcome of the increased index of oxygen development by means of photosynthesis.

Variables

In the independent variable, the intensity of the luminescence is assessed  in each of the trials with the distance from the syringe evaluated using a metric ruler ranging in distances from 10 ± 0.05 cm to 20  ± 0.05 cm,. In the dependent variable a chronometer is applied in order to assess the time required for the discs to float with a margin of error of ± 0.1 seconds.

Materials

1. Syringe
2. Spinach leaf Discs
3. Straw (1.3 cm diameter).
4. Baking Soda
5. Water
6. 125 W Clamp on light.
7. Ruler
8. Stopwatch

Procedure

A baking soda solution was made with 6 g of baking soda to 300 ml of water. A syringe was adapted and the leaf discs and the baking soda were placed into the syringe. The volume of the syringe was 5 ml. The light was originally maintained 10 cm, 12 cm, 14 cm, 16 cm, 18 cm, 19 cm and 20 cm from the syringe. The amount of time required for all of the leaf discs to rise had been recorded. Ten leaf discs were cut with each straw and blown into the syringe for each of the trials at 10, 12, 14, 16, 18, 19 and 20 cm from the light source.

Fig. 1: Number of Leaf Discs that Ascended to the Top of the Syringe (Trial 1 = 10 cm and Trial 7 = 20 cm).

In order to classify the circumstances where the gaseous emissions were maximized, the leaves had been previously exposed to the presence of carbon dioxide or left in the absence of carbon dioxide. The oxygen gas had only been created when there had been high levels of carbon dioxide. This had been the case when the leaf discs had been blown out of the straw. The oxygen had been sent out almost at close to maximal indices in the absence of the carbon assimilation that is caused by photosynthesis.

Notwithstanding, the deficiency of the requisite for net photosynthetic assimilation of carbon dioxide as a motivator of the oxygen emission, the dependency on the qualities of light had been equivalent during the processes of photosynthesis. The index of oxygen formation that had been made by the leaf discs had been determined to be less than 13 nano moles C/m²s in areas where there had been no light. The amount of the quantity yielded for carbon dioxide uptake had been 0.05 mole carbon dioxide and the oxygen value was 0.0003 mole of oxygen C/mol.

There had only been 0.6% of the index for the carbon dioxide uptake. After the review of the gas exchange qualities of the leaf discs under the environmental conditions, there had been a positive relationship that was established between the index of photosynthetic carbon dioxide emission and the emissions of oxygen. Consequently, although the index of the creation of oxygen is not reliant on the spontaneous index of photosynthesis, the leaves that have the highest potential for the assimilation of carbon dioxide also demonstrate the carbon assimilation that is manifested as oxygen at an environmental temperature of twenty-five degrees centigrade. As manifested per unit of dry weight of the 1.3 cm leaf discs, the emissions of oxygen maintained an average of 76 ?g.

The leaf ascending experiments had been performed in order to ascertain in a decline in the concentration of oxygen was correlated with a change in the index of light emissions. In the case of some of the trials of the leaf discs, the index of photosynthesis and oxygen appeared to increase together. This is what caused the leaf discs to rise to the top of the syringe. The interval of time that had been manifested between the distinct varieties of leaves demonstrated that the distance maintained by the chloroplasts influences the lag time required for the leaf discs to ascend to the top of the syringe. This is in alignment with the morphology of the leaves.

The causal attribute of the rapid growth of the leaves, the gas transfer must take place rapidly and this is manifested by the number of bubbles that were demonstrated on the leaf discs. The amount of bubbles demonstrated on the leaf discs can be applied as a tracer for the carbon dioxide diffusion. Consequently, in addition to the maximization of the area of the leaf discs for light absorption in the chloroplasts and to provide for the nutrition and refrigeration of the leaf by means of transpiration, the formation of the leaf asks had s the outcome of maximizing the exchange of gases. A complication that can be realistically perceived is that not all of the thylakoids are equidistant from the gas space, there is a greater distribution of distances needed in the syringe model. The increase distances required for the leaves to ascend would be contributors to the distinctions in the lag time and the ascent time of the gaseous accumulation signal. In addition, the ascent paths of the leaves contain the sink matrices for the oxygen which are found in the mitochondria of the leaves.

The modifications in the changes of pressure within the syringe are restricted by the transfer of gas. These assessments and their paradigms are an effective manner of manifesting the formations within each of the leaves. A leaf that has a spongy and loose quality will have a brief lag interval and ascent interval while leaves that are thicker and more inviscid will manifest a longer lag interval and a leisurely time of ascent.

Discussion

In the laboratory report it can be assumed that the stomata of the plant leaves are open. In the application of the mean dimensions of ten microns and the density of air of the stomata 10⁴/cm², it could be assessed that the pressure calibration interval between the atmosphere and the inner gas leaf spaces would be approximately one half second. In the event that the stomata of the leaves are closed, there would be an effect similar to a drum due to the structure of the leaf being elastic. There have been studies that indicate the effect of the formation of gas bubbles on the leaves can be perceived.

The need for light regarding the emissions of oxygen and the similar qualities in the responses involving photosynthesis and the emission of oxygen are in alignment with the inclusion of the photo synthetics transport matrix in the provision of reductant with ATP for the production of oxygen. The creation of hydrocarbon oxygen from the products that are photosynthetic have the requisites of distinct amounts of reductant, notably NADPH. Presently, it is not known the manner by which this type of reductant responds of ATP responds with the chloroplast, mitochondrial or cytoplasmic processes.

The gas exchange index for leaves with teeth is higher than the gas exchange for leaves not demonstrating teeth. The surface features of the leaves are correlated with robust gradients especially where the relationship between volume and surface area is the most extensive. It can be assumed that there is a homogenous distribution of stomata on the leaf, the transpiration rates should be the most elevated in leaves that have teeth. Young leaves have been demonstrated to have a disproportionate quantity of teeth.

There have been a variety of studies that have seen the influence of the changes in the environmental carbon dioxide concentrations regarding the indexes of oxygen emission. A few of the studies have manifested that the oxygen production is at its most elevated point when the carbon dioxide indexes are minimal. An observation has been applied in order to establish a connection between photorespiration and oxygen production. This is attributed to the dec4esased indices of carbon dioxide having the outcome of elevated photorespiration indices. Additional work is required regarding the influence of the minimal carbon dioxide amounts on the production of oxygen.

The oxygen emission rates had been consistent for the leaf discs in the sample in comparison to the distance of the light source. The elevated influence of the carbon dioxide is not attributed to the closure of the stomata. The enhanced carbon dioxide partial pressures could deter the biosynthesis of oxygen by creating disequilibrium between the phosphate balances of the cytoplasm and the chloroplast, as has been recommended for some of the carbon three species of plants. It could also be that the elevated levels of photosynthesis that are the outcomes of the increased substrate carbon dioxide accessibility could deter the biosynthesis of oxygen by vying for the reductant.

There have been a number of studies that have interpreted the stomatal aperture and the oxygen production in distinct manners. In the experiment, the elevated levels of oxygen notwithstanding the minimal stomatal conductance’s, infers that the oxygen is readily diffused through the cuticle tissues of the leaf disc samples. It has also been observed that the declines in the environmental humidity have had the outcome of declines regarding stomatal conductance in addition to the deceased index of oxygen production. The direct relationship in the decreases of the two variables may be a coincidence. The decreased environmental humidifies have been demonstrated to have the outcome of decreased conductance through the plant cuticles due to the diffusion of water vapor.

The induction of the decreased conductance of the cuticles regarding oxygen diffusion by the decreased conditions of humidity in the environment may be the causal attribute of the decreased oxygen emission indexes that had been documented at the elevated levels of humidity. Considering the previous research that has been conducted with entire plant canopies, the temperature of the leaf and the production of oxygen has been shown to have a high correlation. Studies have demonstrated that the temperatures that had been found between thirty-five and forty-two and a half degrees centigrade are representative of a small amount of the production of the photosynthetic carbon dioxide. Consequently, during the days during the summer which are warmer, there could be a substantial carbon costs to some of the plant species in producing oxygen.

Conclusion

The causal attributes that are the foundation which demonstrate the oxygen production and evolution in certain plants have yet to be ascertained. The outcomes of the experiment show that under specific conditions, the production of oxygen is representative of a substantial sacrifice to the plants. The production of oxygen is correlated with the carbon gain ability of the leaves. Presently, there are no advantages to oxygen emission. It could be that the oxygen production is simply representative of the seepage of the precursors for the diverse isoprenoids.

The manifestation of a probable association between the emission index of the oxygen and the reactions of electron transport during photosynthesis may have effective outcomes for the future modeling endeavors. The majority of the present models of the oxygen changes from vegetation to the atmosphere are reliant on algorithms that are empirically derived from a restricted amount of plant species. Considering the metabolic association to the processes of photosynthesis, there can be effective progress made toward the production of the fundamental mechanistic paradigms that delineate the oxygen emission in the context of the photosynthetic production. These paradigms are required to have applicability regarding a more expansive population of spinach and plant species.