Photosynthesis - Lab Report Example

Yoo Jin Choi Biology 1108 2/4/14 Photosynthesis Lab assignment Introduction Photosynthesis is a process by which light energy is converted into chemical energy. It involves uptake of carbon (IV) oxide and release of oxygen. Being an enzymatic process, there are other factors that regulates it. There is a relationship that exists between photosynthesis and respiration in regard to the exchange of the respiratory gases i.e. oxygen and carbon (IV) oxide (Berg 71). In this experiment, Light as a necessity of photosynthesis is the variable under investigation. According to the research design in this experiment, leaf disks float rate would be used to measure rate of photosynthesis and respiration.
Research questions
Is light a necessity in photosynthesis?
Does 0.4% concentrated sodium bicarbonate solution produce more carbon (IV) oxide than 0.2%?
Is the rate of carbon (IV) oxide diffusion affect rate of photosynthesis?
Hypothesis
If the cups are covered, the leaves will sink.
0.4% concentrated sodium bicarbonate solution produce more carbon (IV) oxide than 0.2%
The rate of carbon (IV) oxide diffusion affect rate of photosynthesis
Method
Experimental Design:
-The leaf disks are put in clear plastic cups with water
- One portion of the experimental cups are added sodium bicarbonate solution while the others, are left as control without sodium bicarbonate
- The cups are partly exposed to light while another portion is placed in darkness
-In the two cases above, number of floating leaf disks are recorded against time as shown in the table below
- CO2 is obtained through the 0.2% of carbonate (sodium bicarbonate solution) so that all the other necessities of photosynthesis are held constant except light.
For Control experiment, 0.2% of carbonate (sodium bicarbonate solution) will not be added to a portion of the cups.
Float out of 10
Control: not carbonate added
Light: photosynthesis
Dark: Respiration
Results
Results: Table 1
In table 1 above figure 1, the rate leaves floats with time indicating that photosynthesis is taking place in the presence of lit. This can be seen with the upward sloping curve. On the other hand, in figure 2, the leaves are sinking gradually due to absence of photosynthesis as a result of no light. This can be seen from the down sloping curve.
Design
0.2 % carbonate: 0.2% of sodium bicarbonate solution
0.4% NAHCO3
Result: Table 2
Light
In the table 2 above light is present hence photosynthesis will take place but at higher rate with 0.4% of bicarbonate which produces more carbon (IV) oxide than 0.2% concentration hence the observed higher rate of floating in 0.4%. However at a certain time, rate of photosynthesis reaches optimum point indicated by 10 floats which is the maximum.
Result: Table 3
Dark
In table 3 above, the number of floats is constant at 10 for different bicarbonate concentrations due to darkness in which photosynthesis cannot take place to produce oxygen.
Results Errors must have arose from
-Because of lower temperature than when we did experiment on light reaction
- We didn’t carrying out stirring in every 5 minutes.

Conclusion
The following conclusive results would be made out of this experiment.The leaves disks are able to undertake photosynthesis in water as they use dissolved carbon (IV) oxide and oxygen also for respiration. This is why the experiment was able to be successful in water. It is also worth to note that rate of photosynthesis is influenced by carbon (IV) oxide supply as indicated by the higher rates in floats by 0.4% of bicarbonate more than 0.2%. It can also be noted that rate of leaves disks were higher in the presence of light than darkness from the observations above proving that light is necessity for photosynthesis holding other factors constant.
Work cited
Berg, Linda R. Introductory Botany: Plants, People, and the Environment. Belmont, CA: Thomson Brooks/Cole, 2008. Print. Read More