Photosynthesis

  • Uncategorized

PHOTOSYNTHESIS

Living organismsneed free energy and matter in order to maintain order, grow, andreproduce. The availability of energy is not only important to oneorganism, but they cause disruption at the population and ecosystemlevel when it is absent (Jones, Fosbery, Gregory &amp Taylor, 2014).Autotrophic organisms harness free energy from their surroundingthrough photosynthesis and chemosynthesis while heterotrophs obtainfree energy from other organisms. Multicellular plants havechloroplasts where photosynthesis occurs within their cells. Theprocess takes place in a series of enzyme-catalyzed reactions thatcapture light energy to make energy-rich carbohydrates (Peter, Paul &ampBeverly, 2013). Essential raw materials in photosynthesis are carbon(IV) oxide and water. There are factors that affect the rate ofphotosynthesis and consequently, the amount of carbohydrates andoxygen produced. They include light intensity and wavelength,temperature, enzymes, and the amount of carbohydrate. This paperreports the experiment conducted to study photosynthesis and factorsaffecting it using floating disk assay.

Hypothesis

Leaf disks do notrise to the surface of water when they are exposed to a source oflight.

Materials

Baking soda

A healthy fresh picked leaf

Several small clear glasses

A bright light (100 watt)

An optional hand lens

Hole punch or stout plastic straw

1 Plastic syringe

Dish soap

Procedure

Floating Disk Assay

Bicarbonate solution was prepared by dissolving an eighth of ateaspoon of sodium bicarbonate in 300 ml of water. About 1 ml ofdilute soap was mixed with Na2CO3 solution. Atleast ten uniform leaf disks were cut for each trial usingsingle-hole punches. The piston of the syringe was removed to allowplacing of leaf disks into the barrel. The piston was replacedcarefully without damaging the disks. The piston was pushed to ensurethat at most 10% of the volume is occupied by air. A small portion ofNa2CO3 solution was sucked into the syringe tosuspend the disks. The disks and solution were transferred to a clearglass. Bicarbonate solution was added to a height of 3 cm. A controlsetup was prepared. Disks were infiltrated with water only with asmall amount of soap. The two cups were placed under the lightsource.

Variables Affecting

The variableexamined in this part was light intensity. The floating disk assayprocedure was used to produce two preparations. One was exposed toambient light while the other was placed in a dark place. The numberfloating disks were recorded with time for the two preparations. Theresults were compared with the outcomes of the floating disk assayexperiment.

Results

Table 1: Floating Disk Assay

Minutes

No. of Floating Disks in Bicarbonate

No. of Floating Disks without Bicarbonate

1

0

0

2

0

0

3

0

0

4

1

0

5

1

0

6

2

0

7

3

0

8

4

0

9

5

0

10

5

0

11

6

0

12

8

0

13

8

0

14

9

0

15

10

1

16

10

2

17

10

2

18

10

2

19

10

3

20

10

3

Table 2: The effect of variables on rate of photosynthesis

Minutes

No. of Floating Disks in ambient light

No. of Floating Disks in the dark

1

0

0

2

0

0

3

0

0

4

0

0

5

0

0

6

1

0

7

1

0

8

1

0

9

2

0

10

2

0

11

2

0

12

3

0

13

3

0

14

4

0

15

5

0

16

5

0

17

5

0

18

6

0

19

7

0

20

7

0

The graph below shows the effect of exposing a plant light, ambientlight, and darkness to the rate of photosynthesis.

Figure 1: Effect of light variables on photosynthesis

Discussion

Question 1: According to Perry, Morton &amp Joy (2012), Thebicarbonate acted as a source of carbon for the process. The overalldensity of the leaf disks increased when the air spaces were filledwith the solution and result in their sinking.

Question 2: releases oxygen into the interior of the leaf disks(Recce et al., 2015). This process results in changes in thebuoyancy of the disks making them rise to the surface of thebicarbonate solution. The equation below summarizes the process ofphotosynthesis.

2 H2O + CO2+ Light → C6H12O6+ 6 O2

Question 3: The changes I would have made to improve the experimentinclude increasing the temperature and light intensity. I wouldincrease the temperature to 300C to enhance the reactionscatalyzed by enzymes (Perry, Morton &amp Joy, 2012).

Question 4: I used a control in part 2. It involved placing thepreparation in a dark place.

Question 5: Quantitative method was used in both Part 1 and Part 2 ofthe experiment. The investigation of photosynthesis involved themeasurement of numerical data such as time and number of floatingdisks (Devorshak, 2012).

Conclusion

is the process by which multicellular plants withchloroplasts manufacture food substances using carbon (IV) oxide andwater in the present of light energy. Oxygen is released during theprocess. The production of oxygen makes the leaf disks buoyant andcauses them to rise. The experiment used quantitative methods becauseit involved the measurement of numerical values.

References

Devorshak, C. (2012).&nbspPlant pest risk analysis: Concepts andapplication. Wallingford, Oxfordshire, UK: CABI.

Jones M., Fosbery R., Gregory J. &amp Taylor D. (2014), CambridgeInternational AS and A Level Biology Coursebook with CD-ROM,Cambridge University Press

Perry J., Morton D. &amp Joy P. (2012), Laboratory Manual forNon-Majors Biology, Cengage Learning.

Reece B., Meyers N., Urry L., Cain M., Wasserman S. &amp Minorsky P.(2015), Campbell Biology Australian and New Zealand Edition,Pearson Higher Education AU

Russell, Peter J., Hertz, Paul E., &amp McMillan, Beverly.(2013).&nbspBiology: The Dynamic Science (Units 1 &amp 2).Brooks/Cole Pub Co.