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PHOTOSYNTHESIS & THE ENVIRONMENT

NOTE! 

This is an essay written on the above mentioned topic. It has been added under additional topics, as it may include information one might find helpful, or information that has not been discussed in much detail in the notes section. DO NOT COPY PASTE THIS. 

You may use it as inspiration if citation is given. 

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Author: Amina Haider

Date added: 26th August 2018

UNIT: Energy from food and movement of substances 

STATEMENT OF INQUIRY: "functionality of organisms is dependent on the balance of materials which is the result of the unbalance and subsequent movement of those materials within that organism which interact with their natural environment in the process to transfer energy for sustainability in the ecosystem."

KEY CONCEPT: Systems

RELATED CONCEPTS: Balance, Transformation, Energy, Movement

GLOBAL CONTEXT: Identities and Relationships 

Photosynthesis

According to Vidyasagar in 2015, “Photosynthesis is the process used by plants, algae and certain bacteria to harness energy from sunlight into chemical energy.”

 

The two types of photosynthesis processes are oxygenic photosynthesis and anoxygenic photosynthesis, with oxygenic photosynthesis being more common of the two.

 

In oxygenic photosynthesis, carbon dioxide and water molecules through sunlight are turned into glucose and oxygen molecules in the equation, ‘6CO2+6H2O + light energy --> C6H12O6+6O2’. 

 

Oxygenic photosynthesis acts as a counterbalance to respiration, as it takes in the carbon dioxide produced through respiration, and releases oxygen back into the atmosphere (Vidyasagar, 2015).

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Figure 1 Plants use sunlight in Photosynthesis (Encyclopaedia Britannica, 2015)

Anoxygenic photosynthesis does not use water and does not produce oxygen in the process either. It typically occurs in bacteria such as purple bacteria and green sulfur bacteria. The chemical equation for anoxygenic photosynthesis is ‘CO2+2H2A+ light energy --> [CH2O] +2A+H2O’. The letter ‘A’ in the equation is a variable and can be substituted by any potential electron donor. In oxygenic photosynthesis H2O acts as the electron donor, but in anoxygenic photosynthesis it could even be Sulfur (Vidyasagar, 2015).     

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Photosynthesis can be divided into two types of reactions, light dependent reactions and light independent reactions. In light dependent reactions solar energy is converted into chemical energy in the form of NADPH and ATP, which are later used in light independent reactions to fuel the assembly of sugar molecules (Boundless, 2016). Later in light independent reactions, carbon is fixed using ATP and NADPH.

Chloroplast

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Chloroplast is an organelle which only plants contain. Chloroplasts contain a pigment called chlorophyll which makes plants appear green, and enables the process of photosynthesis. Chloroplast is very important in the ecosystem, because without it plants wouldn’t be able to make their food, and energy would not enter the food chain (Study.com, 2017).

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Chloroplasts can be found inside the cells of the mesophyll in plant leaves. There are around 30-40 chloroplasts per mesophyll cell. Chloroplast is one of the few organelles which have a double membrane. Inside chloroplast, there are stacks of thylakoids (called grana), and stroma (dense fluid inside chloroplast) (Study.com, 2017).

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Thylakoid contains chlorophyll which is necessary for photosynthesis. The main role of chloroplast during photosynthesis is to contain the reaction itself.  All the required material is transported into the leaves (where chloroplasts are), and the reaction takes place. Chloroplast essentially works like mitochondria, the powerhouse of a cell, but the only difference is that chloroplast creates its own food, and uses this food to power the cell (Study.com, 2017).

Figure 2 Labeled Chloroplast Diagram (Snaprevise Pty Ltd , 2016)

Chlorophyll molecules sit on the surface of each thylakoid, and capture light energy from the sun. After these energy rich molecules are created by light dependent reactions, they move to the stroma were carbon is fixed and sugars are synthesized. Stacks of thylakoid are connected by stroma lamellaes which acts as a skeleton for the organelle. If all the thylakoid stacks were overlapping, it would not be an efficient system of capturing the most amount of light energy and utilizing it (Andrew Rader Studios, 2017).

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Impacts of Photosynthesis

Photosynthesis is the main factor that controls our environment. Without photosynthesis, there would be little or no organic matter on this planet, most organisms would cease to exist, and in some time there would be almost no oxygen in Earth’s atmosphere. The only organisms capable of living in these environments would be chemosynthetic bacteria, which can use the chemical energy of certain inorganic compounds (Lambers & Bassham, 2017).

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It is energy produced millions of years ago, through the process of photosynthesis which is stored in the form of fossil fuels, and now powers our industrial society. Also, as photosynthesis uses up carbon dioxide in its process, it is one of the main ways humans can stop or even reverse the devastating effects of climate change (Lambers & Bassham, 2017). Not to mention, that complete ecosystems depend on producers to bring energy into the food web using photosynthesis. Most of the world obtains 80% of their food directly from plants too (Pass My Exams, 2016).

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Conclusion

In conclusion, photosynthesis is quite simply the use of light to create chemical energy for plants. Chloroplasts are vital in the process of photosynthesis because they contain an organelle called chlorophyll which absorbs all light coming from the sun, and also because it is inside the organelle that photosynthesis takes place. Chloroplasts are only found in plant cells and are like mitochondria both structure and function wise. Photosynthesis is very important as without it life on earth would not be possible, except for a few cases like certain types of bacteria. Photosynthesis allows energy to enter the ecosystem, as it uses sun light, water and carbon dioxide and changes it into glucose and oxygen. It acts as a counter to respiration by producing oxygen and balancing atmospheric gasses. With new problems emerging and becoming more serious simple solutions, such as increasing processes like photosynthesis can solve issues like global warming.

 

Photosynthesis was also important millions of years ago, when dead organic matter was pressurized into becoming fossil fuels, which now are so abundantly used everywhere. Without the process of photosynthesis life would be non-existent and hence it is safe to say that the process does in fact control the environment of this Earth.

References

Andrew Rader Studios. (2017). Chloroplasts - Show Me the Green. Retrieved February 11, 2017, from

Biology4kids.com: http://www.biology4kids.com/files/cell_chloroplast.html

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Boundless. (2016, May 26). Processes of the Light-Dependent Reactions. Retrieved February 11, 2017, from Boundless.com:

https://www.boundless.com/biology/textbooks/boundless-biology-textbook/photosynthesis-8/the-light-dependent-reactions-of-photosynthesis-81/processes-of-the-light-dependent-reactions-376-11602/

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Encyclopaedia Britannica. (2015, January 5). Leaf. Retrieved February 11, 2017, from

Encyclopaedia Britannica: https://www.britannica.com/science/leaf-plant-anatomy

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Lambers, H., & Bassham, J. A. (2017, January 26). Photosynthesis. Retrieved February 11, 2017, from

Encyclopaedia Britannica: https://www.britannica.com/science/photosynthesis

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Pass My Exams. (2016). The importance of Photosynthesis. Retrieved February 11, 2017, from Pass my

exAms: http://www.passmyexams.co.uk/GCSE/biology/importance-of-photosynthesis.html

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Snaprevise Pty Ltd . (2016). (Plant) Cells. Retrieved February 11, 2017, from

The A Level Biologist - your hub: http://www.thealevelbiologist.co.uk/cells-2

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Study.com. (2017). Chloroplast: Definition, Structure, Function & Examples. Retrieved February 11, 2017, from

Study.com: http://study.com/academy/lesson/chloroplast-definition-structure-function-examples.html

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Vidyasagar, A. (2015, July 31). What is Photosynthesis? Retrieved February 11, 2017, from Live

Science: http://www.livescience.com/51720-photosynthesis.html

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