Annotated Bibliography

Phototropism is the growth of a plant in the direction of its light source. Phototropism occurs due to a hormone called auxin which is produced at shoot tips. Auxin influences cell division, if there is light on one side then the dark side will receive more auxin and therefore more cell division will occur on that side, which will force the plant to bend towards the light therefore affecting the height of the

The leaves of a plant are the main photosynthetic organs and are involved in gas exchange and water transportation throughout a plant (Evans et al, 17). A leaf typically consists of an upper and lower epidermis, the mesophyll cells, veins, guard cells and stomata. The mesophyll cells contains spongey cells which have large gaps between each cell to allow oxygen and carbon dioxide circulation. The mesophyll cells contain palisade cells, which are located beneath the upper epidermis. The palisade cells contain many chloroplasts, which are green organelles. Located in the internal layers of chloroplasts is the pigment chlorophyll which is involved in trapping the light energy in photosynthesis (Evans et al, 17).

An example phototropism are the Narneys’ leaves. Similar to sunflowers their leaves move with the sun. Following the sunlight allows them to capture the maximum amount of light energy.

To understand pigments and their part in the essential process of photosynthesis, we constructed an experiment to discover first-hand the effectiveness of specific pigments found in pimento leaves. These two exercises would specifically focus on the difference in polarities and the different wavelengths at which each pigment absorbs light. The ultimate source of energy for most organisms is sunlight. This research expresses the importance in understanding the driving force behind crucial photosynthetic organisms that are responsible for converting solar energy into chemical energy and ultimately the fixation of carbon dioxide. The polarity of three of the specific pigments studied, chlorophyll a, chlorophyll b, and xanthophylls, was determined by separating the plant pigments by paper chromatography and calculating their Rf values. Once the pigments separated along the paper chromatography strip, we cut the different pigments bands and eluted them from the paper into a beaker filled with acetone. We were then able to analyze the wavelengths of light absorbed by the pigments through the use of a spectrophotometer. We predicted the wavelengths for chlorophyll a, chlorophyll b, anthocyanidins, xanthophylls, and carotenoids. From the first experiment we were able to determine that xanthophylls, which traveled the farthest of the three, was

A bar graph representing how much photosynthesis three separate Elodea plants were able to perform under three different light treatments, normal, red and green light. The light treatments enhanced certain wavelengths of light which, due to the absorption spectrum of chlorophylls a and b and carotenoid pigments, altered the amount of photosynthesis a plant was able to perform in a certain amount of time. Each Elodea plant was subjected to a different light treatment, one to normal light, another to red and the third to green light while in a test tube of water for a total of two hours. Photosynthetic processes were observed by means of water displacement in the pipette attached to the test tube and were measured in millilitres. The mass of

Plant growth is dependent on environment factors and the activities of the meristematic tissues after germination (Dunlop et al, 2010). Some environmental factors that will affect plant growth are soil pH and external stimulus. Most plants can only grow well within a narrow range of pH values; 6-8 (Dunlop et al, 2010). Any soil that is more acidic or basic will result in poor or no plant growth. Phototropism is the growth response of a plant to light due to an unequal distribution of auxin (Dunlop et al, 2010; Tucker, 2006). This causes the plant to grow towards the light source and the cells on the side opposite to the light elongate. Dunlop & Tucker state that this results in the stem curving towards the direction of the light.The meristematic

Plants rely upon photosynthesis to acquire their energy and make food. To determine exactly how important light energy is in the process of photosynthesis, we decided to conduct an experiment in which an Elodea plant was exposed to different light intensities. One Elodea plant was placed inside CO2 saturated water and under full light exposure while the other was covered with mesh clothing. The solutions to this plants were then neutralized and compared to a control group beaker which had no Elodea to see the

Plant Hormones are small chemical messengers that act as internal signals within a plant. (Campbell et. at., 2011) Plant hormones are also known as Phytochromes. Plants, unlike animals, lack glands that produce and secrete hormones. Instead, each cell is capable of producing hormones (2). For over two millennia, people have observed that one part of

The Vigna Radiata L, more commonly known as Mung bean, is a plant that demonstrates the general aspects of physiological and morphological growth and development (Xiya Huang, 2013) Photomorphogenic responses, frequency controlled, demonstrates how photosynthesis occurs and how light induces movement (Raven, 2011) The outcome to this is that these responses control a large amount of a plants lifetime development including, seed germination, shade avoidance and flowering (Ying Li, 2011) Photomorphogenisis is therefore the way in which plants develop as well as respond to the environment in which they are thriving (Ying Li, 2011). An investigation was undertaken in order to indentify phototrophic, the growth of organisms in response to blue light (Raven, 2011)and the relocation

5. We observed that corn plants and pea plants (Pisum sativum) grown under the same conditions grew differently: under conditions that were often dry, the corn managed to maintain a larger percentage of green leaf area relative to brown/dry leaf area. Investigate the photosynthetic systems used by corn vs. that used by peas. Compare and contrast these two photosynthetic systems, especially with respect to water availability and usage.

leaves, there are other studies that suggest there should have been a significant difference. For instance, the plant Abutilon theophrasti was shown to have significantly thicker leaves when exposed to high light versus low light conditions (Yun and Taylor, 1986). The study found that there was a positive correlation between leaf thickness and mesophyll surface area and volume Yun and Taylor, 1986). In fact, thicker leaves were shown to exhibit higher net photosynthesis than thinner leaves at high light (Yun and Taylor, 1986). As the light conditions changed, the leaves of the plant had different adaptations in order to maximize photosynthetic productivity. Phenotypic plasticity reflected in an organism’s traits is favored by natural selection because having multiple phenotypes would allow the organism to experience higher fitness in different environments (Ricklefs and Relyea, 2014). Variations in thickness, weight, and surface area allow plants to have higher fitness whether in high or low light conditions. Despite accepting the null hypothesis in this experiment, it is still important to understand how plants, and organisms in general, respond to their environment through phenotypic

from the University of California, and Allen G. Marr studied the effect of light intensity on the formation of intracytoplasmic membrane in Rhodospirillum rubrum. Cells of Rhodospirillum rubrum that were grown at low light intensity were found to contain much more internal membrane than cells grown at high light intensity. These highly purified membranes, known as chromatophores, grow at low to moderate light intensity and had a constant content of chlorophyll. The regulation of the chlorophyll content in the cell depends upon the formation of greater or lesser amounts of membrane which has a constant concentration of chlorophyll (HOLT SC,

In this lab, varying wavelengths were used to test how light affects photosynthesis and respiration as a whole. The absorbance of lights from 380 nm to 720 nm of chlorophyll pigment from the Elodea sample

A plant is any of the boundless number of living beings within the biological kingdom Plantae, these species are considered of low motility since this species generally generate their own food by sunlight. They incorporate a large group of commonplace life forms including trees, forbs, bushes, grasses, vines, plants, and greeneries. In this task we are experimenting the relationship between light and plant growth by growing plants in three different lights which are red light, blue light and white light. As I stated above that plants generate their own food by sunlight. Sunlight can be broken up by a prism into respective colors of red, blue, orange, yellow, green, indigo, violet and white. All this lights have specific

Plant shoots (a newly growing shoot is referred to as a coleoptile) grow toward light. This is positive phototropism.