Analysis of Leaves in Light and Dark Environments

Analysis of Leaves in Light and Dark Environments

Objectives

This experiment aimed to find out the products and reactants of photosynthesis and the environmental sources of the reactants.

The experiment also aimed to explain how physical observations are related to photosynthesis.

Introduction

The ability of plants to carry out photosynthesis, which is the biochemical conversion of light energy from the environment and carbon from the air to glucose molecules, presents a vital aspect in the carbon cycle and food chain. The by-product of photosynthesis is usually oxygen gas, and this explains the high percentage of gas in the atmosphere. In this experiment, observations of the leaf disks in dark and light solutions was to help in explaining the process of photosynthesis and cellular respiration. Throughout the experiment, the net rate of photosynthesis is reflected by the number of floating leaf disks. The photosynthesis equation, according to studies, is written, as shown below:

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂  (Gleason and Raymond 14).

The amount of time taken by the leaf disks to float can help in determining the best environment for high rates of photosynthesis.

Hypothesis

If the leaf is placed in the presence of high light intensity in a carbon IV oxide presence, then the leaf will take a shorter time to float to the top of the solution because high light intensity increases the rate of photosynthesis.

Procedure

• Five uniform leaf disks were cut out using a hole puncher while avoiding the major leaf veins for each trial.
• One cup of water and one teaspoon of baking soda was added to the water in a larger bowl.
• Five leaf disks were then placed in the syringe plunger, and the plunger replaced, leaving only a small air volume.
• The syringe was then used to draw 15 ml of the baking powder into the solution and then tapped to release all of the leaf disks.
• The syringe plunger and tip were released to release the vacuum in the syringe until all of the leaf disks sunk to the bottom of the syringe barrel.
• The syringe was then placed 15 centimeters from the light source with the plunger side down.
• The experiment was then timed immediately after switching on the 60 Watts light source, and the total number of floating disks recorded after each minute. This was repeated until all of the disks were floating.
• The steps were repeated, but this time in a dark place.
• The observations were recorded for 15 minutes.

Results/Data

Conclusion

The experiment was successfully carried out since the objectives were met. The dependent variable was the rates of photosynthesis, while the independent variable in this experiment was the lighting condition. The results found supported the hypothesis since the number of leaf disks floating after 2 minutes in a lighted condition was more than that in a dark condition. The number of floating disks is directly proportional to the rate of photosynthesis. The leaf disks float because due to accumulation of oxygen gas produced during photosynthesis, which increases the buoyancy of the leaf disks. During respiration, the leaf disks use the oxygen produced during photosynthesis while consequently releasing carbon Iv oxide gas. The leaf disks, therefore, sink due to the usage of the oxygen in them. The purpose of the baking soda was to produce carbon dioxide required for photosynthesis.