Ap Bio Research Paper

Stomata are tiny pores found on the epidermis of the leaf, surrounded by guard cells. [1] Their main function is gas exchange [1] for photosynthesis and respiration. The development of stomata on the leaves of a plant is determined by interaction between different genes and environmental factors. A few studies have been conducted in order to establish a relationship between stomatal densities and given environmental factors. Research has shown that stomatal densities are controlled by environmental conditions during leaf development, but are fixed after the leaf matures. [2]

The article "The influence of light on stomatal density of a tomato" by A. P. Gay and R. G. Hurd describes their findings that plants grown under high light intensity
The second aim of the investigation was to find out whether the initial height of the plant influences its stomatal density. Cuttings were taken from lavender plants to ensure that all the plants were genetically identical and that the only changes occurring in the stomatal density would be due to environmental conditions. Four cuttings were short (3 cm initial height) and four were tall (6 cm initial height). The cuttings were put under compact fluorescent light bulbs with four different power ratings (8, 11, 14, and 20 W). One short and one tall cutting were put under each of the four light bulbs for 28 days in order to grow them. Both the short and the tall plants showed a positive correlation between their stomatal densities and the light intensity. The correlation was statistically significant at a 0.025 significance level according to the Pearson product-moment correlation test. The short and the tall plants grown under the same light intensity did not show any statistically significant difference between their stomatal
Photosynthesis is the process by which plants synthesize glucose from carbon dioxide and water. The energy of the reaction is supplied by the sunlight. However, there are two main stages in photosynthesis - light-dependent and light-independent stages. [11] The light-dependent stage depends on the light because the energy from the light is used to split water in the process of photolysis and excite electrons in the chlorophyll. [11] The products from the light-dependent stage are ATP and the electron acceptor - reduced NADP. [11] The products from the light-dependent stage are fed into the light-independent stage of photosynthesis, the Calvin cycle. [11] Carbon dioxide is fixed in the light-independent stage and converted to glucose; in the Calvin cycle, the products of the light-dependent stage are needed. So, more ATP and reduced NADP will result in an increased rate of carbon fixation. If the rate of carbon fixation increases, the rate at which carbon dioxide diffuses in and out of the leaf will increase.

The light intensity is simply the energy per second per unit area carried by the incident light and it is proportional to the number of photons per second carried by the incident light. [12] Higher light intensity means more photons per second resulting in more electrons per second that would be excited during the light-dependent stage of photosynthesis, and more ATP and reduced NADP are produced.