Lab Report Plant Nutrition

LabReport: Plant Nutrition

Abstract

Plantsare one of the major food items consumed by man. There are so manyscholars who encourage the consumption of plant parts and products asopposed to animal products. The main food substance obtained inplants is the carbohydrates. Carbohydrates are stored in plants inthe form of starch, a complex of many glucose units joined byglycosidic linkages. Amylase is the enzyme responsible for breakingdown starch into glucose. The paper demonstrates the varyingdifference in composition of glucose and starch in different parts ofthe plant. There are two experiments described in the paper, theexperiment on the glucose level and the experiment on the starchlevel. There is a debate on whether the fruits of the plants havemore nutritional value as opposed to other parts like the Leafs. Thepaper tries to relate whether the nutritional value of the plantparts is what pushes consumers to consume more of these parts asopposed to other parts.

Theearth is made up of flora and fauna. However, plants are the mostabundant sources of food on earth. The plants can give the body therequired nutrients that are necessary for the functioning of the body(Stokstad,2010).For instance, of all the thirteen essential vitamins, eleven arefound abundantly in plants. The body requires an abundant amount ofenergy to function normally. The primary source of this energy in thebody is carbohydrates. The plants can readily manufacture thesecarbohydrates by use of sunlight through photosynthesis. Thecarbohydrates are stored in the plants in complex forms known asstarch (Zeeman,Kossmann, &amp Smith, 2010).Human beings can, therefore, obtain starch by eating these plants.Since the human body cannot use starch in its complex form, enzymeamylase is used to convert the complex starch to simple glucosecompounds that can be absorbed by the body (Zeeman,Kossmann, &amp Smith, 2010).

Asalready mentioned, Glucose is a simple form of starch. In otherwords, starch is formed by joining of several units of glucosethrough glycosidic linkages. It is these linkages that are cut offby amylase when breaking down starch into glucose (Zeeman,Kossmann, &amp Smith, 2010).The enzyme is readily found in the saliva. This experiment seeks todemonstrate how the varying composition of starch in the plant partsaffect the choice of the parts we eat.

Hypothesis

Therewere two hypotheses in this experiment:

  • The leaves, the vegetative parts of plants will contain the most glucose compared to roots, stems, and fruits. This is because leaves are the site of photosynthesis, of which one of the major products is glucose.

  • The reproductive part, particularly of the fruit will have the most starch in comparison to roots, stems, and leaves. This rationale is because starch is needed for nourishment and energy of the seeds located inside of fruits.

Materialsand Methods

Experiment1: Starch – 1c: Starch Content in Foods

Materials:test tubes, test tube holders, motor and pestle, Samples (parsnip,apple, celery, and bamboo), slightly boiling water, source of heat,tap water, Lugol’s iodine solution, graduated cylinder, ), Amylase(on ice), 1% Starch solution, tape for labeling

Procedure

First,the test tubes were rinsed with water and 5ml of each sample added toseparate test tubes. 2gms chunk of separate food plant samples wasobtained for use in further testing of the individual hypotheses. Thefood substance was put into the mortar and 10ml pf tap water added.The contents were then ground and mashed. %ml of the solution wasdrawn and put into a clean test tube and labeled. The mortar wasrinsed and the experiment repeated for other food plant samples. Thetest samples were then heated in boiling water for 45 seconds. Afterheating the samples were retrieved using the test tube holder andcooled in running tap water. After cooling, five drops of Lugol’siodine solution was added to each sample and the results recorded.The color changes were observed and recorded on a table for use infurther analysis.

Experiment2: Glucose – 2c: Glucose Content in Foods

Materials:test tubes, test tube holders, plant food samples (bamboo, parsnip,apple, celery), Source of heat, Beaker, Benedict’s solution,stopwatch, tape for labeling, graduated cylinder, 10% Glucosesolution.

Procedure

First,all the test tubes were rinsed with water. 5ml of each premixedsample was added into separate test tubes and labeled appropriately.2gms chunk of plant food substances chosen was obtained for furthertests of the individual hypothesis. The first food plant substancewas placed into the mortar and 10ml of tap water added. The contentswere then ground and mashed. 5ml was then extracted into a test tubeand labeled. The mortar and pestle were rinsed, and the experimentwas repeated for other food plant substances and labeled. All theextracted samples w were heated in boiling water for 45 seconds. Theheating was followed by addition of 20 drops of Benedict`s solution.After addition of benedict solution, the test tubes were placed backthe boiling water again for five minutes. The test tubes were thenretrieved using a test tube holder. The expected color changes werethen observed and recorded.

Results

Experiment1

Food Substance Color after adding Lugol`s Indicator

Parsnip

Blue/Black

5

Bamboo

Brown(green and purple)

3-4

Celery

Orange

1

Apple

Amber

0

Orange

Orange

1

Onion

Orange

1

Thetable above was constructed by comparing the colors with those of thecrayon to obtain the starch indicator values. The indicator valueswere then used to construct a graph showing the starch indicatorvalues against the various plant food substances. The graph is asshown below.

Experiment2

Food Substance Color change on heating with Benedict’s reagent Color (crayon) Indicator

Parsnip

Yellow

5

Bamboo

Green

7

Celery

Orange

3

Apple

Dark Orange

4

Orange

Pale Orange

2

Onion

Dark Green

8

Thetable above was constructed by comparing the colors with those of thecrayon to obtain the glucose indicator values. The indicator valueswere then used to construct a graph showing the glucose indicatorvalues against the various plant food substances. The graph is asshown below.

Discussion

Fromthe results, it is evident that different plant parts have differentcompositions of glucose/starch (Buchanan,Gruissem, &amp Jones, 2015).The results showed that the plants recorded different colorsdepending on the intensity of the compounds in these plants. In thefirst experiment, parsnip tap root recorded the highest value forstarch (5) while apple fruit showed the lowest value (0). In thesecond experiment, onion leaf showed the highest value (7) forglucose while orange fruit showed the lowest value for glucose.

Thefirst hypothesis was refuted by the results of the experiment becauseaccording to our hypothesis, the fruit would contain the most starch.Based on the graph the parsnip tap root had the highest starchindicator value in comparison to the orange and apple which were theonly two fruits in the group tested. The roots and the stem were thetwo parts that contained the most. This could be because roots areresponsible for the uptake of water and nutrients in plants, whichalso include starch.

Thesecond hypothesis was refuted by the results of the experimentbecause results for this experiment were inconclusive and therefore adefinitive conclusion about our hypothesis could not be reached. Wepredicted that the leaves would receive the highest glucose valuewhen using Benedict’s test. However, the celery received anindicator value of 3 which would reject our hypothesis. The resultsconflicted for our two leaf groups which made it inconclusive. Thesecond highest value is bamboo, a stem, which might have been due tostems being a general way to transmit nutrients including glucose.

Theobservation that the expectations were refuted may have been as aresult of possible avenues for errors. The differing results wereprobably caused by human error during measurements or during theaddition of the indicator drops. Also, there may have been errors ofjudgment when deciding the final colors of these tests. In general,the discrepancies may have arisen because the experiment was notoptimized. Additionally, there is a need for more sampling of data sothat the averages could be used in determining the actual results ofthese experiments.

Theobservation that the glucose level in apple fruit is higher than thatin orange fruit may be a deciding factor for a consumer (Stokstad,2010).The consumer may choose to consume more of apples as opposed toglucose. Similarly, the observation that parsnip tap root had a highconcentration of starch as opposed to bamboo stem may push a consumerto consume more of parsnip tap root. These observations explain whycertain consumers choose to consume a specific part of a plant asopposed to other parts. For instance, most people consume orangefruits or apple fruits, but not leafs. The fruits have not only sweetflavors but also have other nutritional values that are helpful toman. People may still take in starch as it can be converted toabsorbable glucose by enzyme amylase found in the saliva (Zeeman,Kossmann, &amp Smith, 2010).

Reference

Buchanan,B. B., Gruissem, W., &amp Jones, R. L. (Eds.). (2015). Biochemistryand molecular biology of plants.John Wiley &amp Sons.

Stokstad,E. (2010). Could less meat mean more food?. Science,327(5967),810-811.

Zeeman,S. C., Kossmann, J., &amp Smith, A. M. (2010). Starch: itsmetabolism, evolution, and biotechnological modification in plants.Annualreview of plant biology,61,209-234.