PHOTOSYNTHESIS

Introduction

Photosynthesis

Photosynthesis is the physico-chemical process by which plants, algae and photosynthetic bacteria use light energy to drive the synthesis of organic compounds. In plants, algae and certain types of bacteria, the photosynthetic process results in the release of molecular oxygen and the removal of carbon dioxide from the atmosphere that is used to synthesize carbohydrates (oxygenic photosynthesis). Other types of bacteria use light energy to create organic compounds but do not produce oxygen (anoxygenic photosynthesis). Photosynthesis provides the energy and reduced carbon required for the survival of virtually all life on our planet, as well as the molecular oxygen necessary for the survival of oxygen consuming organisms1 . In addition, the fossil fuels currently being burned to provide energy for human activity were produced by ancient photosynthetic organisms. Although photosynthesis occurs in cells or organelles that are typically only a few microns across, the process has a profound impact on the earth's atmosphere and climate. Each year more than 10% of the total atmospheric carbon dioxide is reduced to carbohydrate by photosynthetic organisms. Most, if not all, of the reduced carbon is returned to the atmosphere as carbon dioxide by microbial, plant and animal metabolism, and by biomass combustion. In turn, the performance of photosynthetic organisms depends on the earth's atmosphere and climate. Over the next century, the large increase in the amount of atmospheric carbon dioxide created by human activity is certain to have a profound impact on the performance and competition of photosynthetic organisms. Knowledge of the physico-chemical process of photosynthesis is essential for understanding the relationship between living organisms and the atmosphere and the balance of life on earth. Several books on photosynthesis are available for the uninitiated (Hall and Rao, 1994; Lawlor, 1993; and Walker, 1992) or advanced student (Govindjee, 1982; Amesz, 1987; Briggs, 1989; Barber, 1992; Scheer, 1991; Bryant, 1994; Blankenship et al. 1995; Amesz and Hoff, 1996, Baker, 1996; and Ort and Yocum, 1996). Taiz and Zeiger (1991) place the photosynthetic process in the context of over all plant physiology, and Cramer and Knaff (1991) describe the bioenergetic foundation of photosynthesis.

The overall equation for photosynthesis is deceptively simple. In fact, a complex set of physical and chemical reactions must occur in a coordinated manner for the synthesis of carbohydrates. To produce a sugar molecule such as sucrose, plants require nearly 30 distinct proteins that work within a complicated membrane structure. Research into the mechanism of photosynthesis centers on understanding the structure of the photosynthetic components and the molecular processes that use radiant energy to drive carbohydrate synthesis. The research involves several disciplines, including physics, biophysics, chemistry, structural biology, biochemistry, molecular biology and physiology, and serves as an outstanding example of the success of multidisciplinary research. As such, photosynthesis presents a special challenge in understanding several interrelated molecular processes.

Task

The green plants are the producers in our environment. They make food for the consumers. What do they need to make food?

Task 1

  • Perform an experiment to determine what plants need to make food.

Task 2

  • Identify the variables in the experiment.

Task 3

  • Observe what happens to plant grow in the absence of any of the factors needed for photosynthesis.

Task 4

  • Infer that plants need air water, and sunlight in food making.

Task 5

  • Explain the process of photosynthesis using a diagram.

Process

Evaluation

 Write the Photosynthesis steps :

Table Photosynthesis

Conclusion

When a plant receives adequate sunlight and water and takes in carbon dioxide chloroplasts in the plants cells convert the reactants ie water and carbon dioxide into oxygen and the carbohydrate glucose. The sunlight provides the energy for this to happen. This is the process of photosynthesis. The conclusion of photosynthesise therefore is oxygen released unto the atmosphere and glucose stored in the plant to feed it. 

The chloroplasts also synthesise starch which is made of glucose molecules stored in a long chain.if you place the plant in darkness it will use up it's food reserves and become de-starched. Starch will only be made where the leaf contains chlorophyll and can photosynthesise. So yes it is correct when plants are in the dark starch will cease to be present, but in the light starch will be present for above reason. 

Hope I have explained this well enough for you to understand. It's so much easier to learn things if you understand them.

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