Biology Extended Essay

Table of Contents

Abstract................................................................................................2

Introduction.......................................................................................................................3

Theoretical Aspects.................................................................................4

Affects of light intensities on plant photosynthesis measured by the amount of oxygen produced...............................................................................................5

Experimental Aspects..............................................................................6

Factors that Affect the rate of photosynthesis.....................................................7

Investigating the Affect of Light on plant photosynthesis....................................8

Hypothesis..........................................................................................8.1

Variables............................................................................................8.2

Apparatus...........................................................................................8.3

Methodology.......................................................................................8.4

Results...............................................................................................8.5

A graph to show the Relationship between light and the rate of photosynthesis........9

 Analysis & Conclusion...................................................................9.1

 Extension Hypothesis

 Variables

 Materials

 Methodology

 Analysis & Conclusion

Conclusion

Bibliography

Further Research

IB Biology Extended Essay (Photosynthesis)

Candalus

Log lux

Thylakoids, add self observations

Abstract

An abstract is an abbreviated summary of a research article, review, or any in-depth analysis of a particular subject or discipline, and is often used to help the reader quickly ascertain the paper s purpose. When used, an abstract always appears at the beginning of a manuscript, acting as the point-of-entry for any given scientific paper or patent application.

Introduction

The subject of my Extended Essay is the "Effects of light intensities on plant photosynthesis measured by the volume of oxygen produced". It is contained within the IB syllabus in Topic 7 on Cells Respiration and Photosynthesis. I intend to observe the volume of oxygen emitted by Elodea pond weed proportional to the differences in light intensities. After reading up on plant photosynthesis and rate of reaction from sunlight, I came to the conclusion that my hypothesis may be supported, I expect that there will be a big difference between the volume of oxygen produced from the pondweed in direct sunlight between the hours of 12:10 and 13:10 than those in front of a light bulb or in a dark cup board. For the analysis of photosynthesis I intend to record the volume of gas produced during a given amount of time, in this case a week, by using accurate measuring device such as a upside down measuring cylinder measuring the number of centimeters squared of gas produced on a given day in a consecutive 7 day week.

Photosynthesis:

All green plants must make their own food, this is carried out in a process called photosynthesis. For photosynthesis to occur they need sunlight energy. This energy is absorbed by a green pigment called chlorophyll, which is mainly found in the leaves of trees but also in aquatic plants. This energy then combines with water molecules (from the soil) and carbon dioxide (from the air). Because of this a sugar called glucose is made and also oxygen. For my experiment I have chosen to use light types as my variable. I will be keeping light the same throughout the experiment in its different forms, (Lamp, Sunlight, and Darkness). The word and scientific equation for photosynthesis is : Carbon dioxide + water to Glucose + oxygen = 6CO2 + 6H2O to C6H12O2 + O2 In depth, Photosynthesis occurs when a chlorophyll molecule is energized by a light photon. This intern leads to the molecule producing a electron. The electron is hen able to be used to convert the ADP into ATP. The process is called 'Phosphorylation'. Due to the chlorophyll lacking an electron, it takes up an electron from the water. The equation is as follows: 'H20 - 2h+ + 2e- + Ð... O2 the 2e'-. Hydrogen is combined to carbon dioxide using ATP for the energy. The equation can be shown as: '6co2 + 6h2o + 2880 KJ/ mol to C6 k + 602' There are two stages to photosynthesis, there is the light dependent and light independent reactions. During the Light Dependent reaction, the suns energy is caught by the chlorophyll molecule, this happens as oxidation. Energy in the form of a photon is required to increase the energy levels of electrons which move out of the chlorophyll during oxidation. The energy must then be linked to the ADP reduction to ATP and coenzyme NADP+ which is condensed to NADPH + H+. This reaction requires light for it to take place, where it occurs on the thylakoid membranes. Energy from the light is converted into chemical energy. The molecules of chlorophyll are then attached to the thylakoid membranes, which can be attached with accessory pigments and different types of proteins to produce a photo system; in the middle of all photo systems there are different types of chlorophyll each one has a specialized task to absorb a certain wavelength of light. The Electrons inside of the chlorophyll absorb the energy produced by the photons and intensifies

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