EBIO 4140 Plant Ecology - Assignment

Running head: PLANT ECOLOGY 1
EBIO 4140
Name of the Student
Name of the University
Author Note

PLANT ECOLOGY 2
Part 1
A biome can be classified as a community with large ecological areas on a global
scale. They are defined by abiotic factors such as vegetation, soils, geology, relief, climate
and temperature. The major types of biomes are forest, desert, aquatic and grasslands. Land-
based biomes are known as terrestrial biomes and water-based biomes are known as aquatic
biomes. Biomes contain several ecosystems within the same ecological area distribution.
Biomes are distributed globally based on the average annual precipitation and average annual
temperature. Trends of temperature are determined by the proximity of the ecological area to
the equator, greater the distance, lower will be the temperature. Areas with more precipitation
tend to have greater vegetation. The biome that receives the lowest precipitation is the desert
biome, a terrestrial biome. The primary characteristics of the desert biome are extreme
temperatures, low humidity, low precipitation, aridity, and drought. Few of the threats
associated with this biome are intense solar radiation, highest potential evaporation, absence
of biological soil, and the soil is sandy, loose and devoid of nitrogen and organic carbon.
Photosynthesis is a critical process that helps the plant to produce organic molecules
and support the functioning of its system. It is defined by the process by which the plants
harness the solar energy from the sun and utilize it to turn into chemical energy, which can be
later exploited by the plant systems for their own activities. The electromagnetic radiation
emitted by the sun is absorbed by the pigments, of which, chlorophyll a and chlorophyll b are
the primary absorbing pigments. Pigment molecules grouped with proteins form a
photosystem, which then absorbs one photon. This photon reaches a single molecule of
chlorophyll a in the reaction center, which gets excited to donate an electron to a primary
electron acceptor. To replace this electron, water molecules get broken to form hydrogen ions
[H+] and oxygen molecule (O2). The donated electron from chlorophyll participates in the
electron chain transport system and increasing concentration of hydrogen ions are allowed to

PLANT ECOLOGY 3
pass through ATP synthase, a protein complex embedded in the thylakoid. ATP is formed
with the process of photophosphorylation. NADPH energy-carrier molecule is generated and
stored in energy carriers and this stored chemical energy will further used in the Calvin cycle
for assembly of sugar molecules. The carbon fixation process during the Calvin cycle is
started with hydrolyzing of unstable 6 carbon molecule to 3-phosphoglycerate. The reaction
is catalyzed by the enzyme RuBisCO.
The carbon fixation process in the Calvin cycle is followed by reduction and
regeneration to form the final product of glyceraldehyde-3-phosphate (G3P). Glyceraldehyde-
3-phosphate is a three-carbon molecule, which is synthesized into organic molecules, starch
and sugar after leaving the Calvin Cycle. The synthesis of the G3P is important for cellular
metabolism. However, an important thing to note that is only one molecule of G3P is
generated per three turns of the Calvin cycle. According to Kirschbaum (2011), an increase of
30 per cent in the net photosynthetic rate has reported showing an increase of only 10 per
cent of the overall plant growth, thus underlying the insignificant correlation of the net
photosynthetic rate and plant growth rate. According to the authors, the realized efficiency of
the photosynthetic process in converting available solar energy into chemical energy is 2 to
4%, which indicates significant inefficiency of the process. Water and nutrient limitation can
be the primary background cause of these statistics.
Water in the plants acts as a medium for the biochemical reactants to dissolve and is
crucial for plant’s metabolism and growth. During the photosynthetic process, water along
with carbon dioxide helps in the synthesis of carbohydrates. More importantly, it acts as a
transport medium for the nutrient movement in the plant. Through the process of
transpiration, passive transportation of water absorbed from roots takes place in the xylem,
which is then released into the air from leaf surfaces by diffusion through stomata (Huang, Li
& Li, 2018). Transpiration can be deemed as a process of evaporation of water in plants. The