Part One: Biological Experiment Design
Photosynthesis refers to the process in which green plants utilize the sun’s light energy to form usable chemical energy. The excess of this chemical energy is stored in plant tissue as starch. The presence of starch in plant leaves is an evidence of photosynthesis in plants. This is based on the fact that starch is formed through photosynthesis.
This experiment seeks to determine the presence of starch in plants. This paper hypothesizes that plants carry out photosynthesis in their leaves. Further, it is conjectured that plants need light energy to carry out photosynthesis. To investigate these hypotheses, the experiment relies on the use of Iodine solution to determine the presence of starch in two plants from same species exposed in different environments. The first plant is kept in a dark room while the other in sunny environment. The plant in the dark room acts as the control for the experiment. Starch is a polysaccharide made up of multiple units of glucose joined together by glycosidic bonds. During condensation reaction, linear chains containing amylose and branched chains containing Amylopectin are formed. According to Nikkanen and Rintamäki (2019), natural starches are made up of a mixture of amylopectin (75-90%) and amylose (10-25%) The helical amylose structure is responsible for the reaction between iodine and starch. The penta-iodide and tri-iodide ions are linear in structure and slide into the helix of the amylose molecules.
Iodine is made up of a small insoluble non-polar molecules. However, Potassium triiodide solution is used as a reagent in the experiment. In particular, Potassium iodide dissociates, leaving the iodine ions to reversibly react with iodine to form the triiodide ion. Further reactions between iodine molecules and triiodide ions yields pentaiodide ions.
The starch and iodide composition is formed as a result of transfer of charged recall electrons between triiodide and starch ions or the later particles with pentaiodide ions. This starch-iodide charge transfer results in the change of spacing between the orbitals. The resultant starch-iodide complex absorbs light at different wavelength resulting into blue-black coloration. It is against this background that iodine is used to test for presence or absence of starch in natural substances. This experiment therefore includes application of iodine on two different plant leaves to determine the presence or absence of starch and draw a verdict of whether or not plants carry out photosynthesis.
Experiment: Test for Starch in plants
Apparatus
2 port plants
1 beaker
Heat source
Iodine solution
Tweezers
Ethyl alcohol
Saucepan
2 shallow dishes
Procedure
- Place the first plant in a dark room away from the sun for 24 hours; and the other in an open sunny place.
- After 24 hours, fill the beaker with ethyl alcohol
- Fill the saucepan with water and place it on heat
- Place the beaker in the saucepan and heat until the alcohol boils
- Remove the beaker from the heat and a leaf from each of the two plants in the hot water for 1 minute using tweezers
- Immerse the leaves in the beaker of alcohol for two minutes
- Place the leaves in separate shallow dishes
- Cover the leaves with iodine solution and record the observations
Observation
Upon application of Iodine solution, the leaf from the plant in the sunny place turns color to blue-black while the leaf from the dark room does not
Discussion
Hot water destroys the leaf, exposing the leaf’s chlorophyll to alcohol which removes the green matter from the leaf. When iodine is put on the leaves, the leaf from the plant in the sunny place turns blue-black indicating the presence of starch while the other leaf does not show any change in its color.
Conclusion
Plants do carry out photosynthesis in the leaves.
Plants require light to perform photosynthesis
Part Two: Discover and Experimental science
Prevention of aging through manipulation of mitochondrial DNA in human body cell could be termed as a typical example of discovery science. This is purely because the study does not have any hypothesis attached to it; rather, it seeks to unravel new knowledge. Discovery science and experimental science although having a number of similarities, have a number of discerning aspects that differentiate the two (Shiffrin, 2019). First, while discovery science mostly concerns itself with describing nature and its mysteries, hypothesis-driven science attempts to explain nature and why some things happen the way they do. According to Shiffrin (2019), discovery science searches for new knowledge while experimental science tests the new knowledge, deducts and conducts investigations
One question that is ever dangling in the minds of scientists is whether or not SI methodologies can be applied in discovery science. Oldfield (2018) argues that although discovery science can help discover new ideas or things that were previously unknown without necessarily needing a hypothesis to test for it, it can find new information in the discovered knowledge. It is against this background that this paper hold that it is possible to apply SI techniques in Discovery science, however they may not be relied on purposely for discovery but to explain, thus in the event that new knowledge is acquired, then the two methods would share the credit . In addition, SI techniques are critical in providing cues to overlooked or forgotten concepts in the discovered phenomenon, thus a valuable source of exceptions in theorems (Oldfied, 2018).
References
Nikkanen, L., & Rintamäki, E. (2019). Chloroplast thioredoxin systems dynamically regulate photosynthesis in plants. Biochemical Journal, 476(7), 1159-1172.
Oldfield, T. (2018, November 18). Hypothesis Based vs. Discovery Driven Analytics. Retrieved August 25, 2020, from https://www.dotmatics.com/blog/hypothesis-based-vs-discovery-driven-analytics
Shiffrin, R. (2019, January 21). Complexity of science v. #PSprereg? Retrieved August 25, 2020, from https://featuredcontent.psychonomic.org/complexity-of-science-v-psprereg/