Share
Explore BrainMass

Photosynthesis

Photosynthesis is a process utilized by plant organisms to produce carbohydrates, in the form of sugars and starches, by harnessing energy from the sun and combining this with CO2 molecules. Photosynthesis takes place in chloroplast organelles which are present in the mesophyll tissue of plant leaves. Furthermore, photosynthesis depends on the presence of chlorophyll, a green pigment, which is found in the thylakoid cells of the chloroplast. 

Figure 1. This figure is a cross-section of a leaf and shows the main components of the leaf structure. The palisade layer is composed of palisade cells which are part of the mesophyll tissue found in leaves. The mesophyll of leaves is comprised of the palisade and spongy cell layers. This image has been taken from:http://en.wikipedia.org/wiki/File:Leaf_Tissue_Structure.svg.

The equation for photosynthesis is as follows: 

6CO2 + 12H2O + light energy  ----->  C6H12O6 + 6O2

Variables:

CO2 = carbon dioxide

H20 = water

C6H12O6 = glucose

O2 = oxygen

Photosynthesis requires a few major photosynthetic compounds in order to produce glucose. As already mentioned, chlorophyll, a green pigment, is required to absorb energy from the sun. Chlorophyll contains a porphyrin ring structure with a magnesium ion at its center. Furthermore, an enzyme called Rubisco is essential to this process. Rubisco is required for carbon fixation during the Calvin cycle, creating a 6-carbon compound which gets broken down into two smaller three carbon compounds.

Overall, photosynthesis involves two components: the light cycle and the dark cycle. CO2 is needed for the dark cycle and is acquired through a plant's stomata, which is a pore on the epidermis of leaves regulating gas exchange. However, the intake of COthrough the stomata represents a trade-off with the loss of water.  

The end objective of photosynthesis is to produce sugars for plants to use as a food source. Photosynthesis is a rather complex process and also varies between different types of plants, such as between C3, C4 and CAM plants.  

 

Categories within Photosynthesis

Light Reactions

Postings: 2

The light reaction is a process requiring the input of carbon dioxide, water and light, in order to produce the reactants required for the dark reaction, the second stage of photosynthesis.

Dark Reactions

Postings: 0

The dark reaction, also called the Calvin cycle as that is the actual mechanism of this reaction, is the second and final phase of photosynthesis.

Cell Chemistry: Enzymes, Metabolism, and Photosynthesis

1) Why are enzymes critical to the function of cells? That is, why not simply let chemical reactions occur without interference? 2) What type of molecules are enzymes (i.e., lipids, nucleic acids, etc)? 3) What wavelengths of light are best suited for use in photosynthesis? 4) Why is photosynthesis critical to nearly ev

Oxygen in seawater.

If all oxygen in seawater comes either from exchange with the atmosphere or from photosynthesis by phytoplankton in the euphotic zone, how do you explain that there is sufficient dissolved oxygen throughout the water column, even in the greatest depths, except in highly unusual locations? how did photosynthesis allow life to com

This is a CAM (Crassulacean acid metabolism) plant

a) from figure 1a describe the pattern of water loss from the plant and explain why this pattern occurs. b) using knowledge of the factors that control stomatal temperature and the data in figure 1b, explain the changes in stomatal resistance during the day as shown in figure 1a. c) From the data in figures 1a and 1b state

Photosynthesis and the Role of Energy

How do Organisms Acquire Energy? How Do Organisms Use Energy? I have to research Photosynthesis - dark reaction and do a PowerPoint Presentation(at least 8 slides) and notes answering these question. What is the purpose of this pathway? What are the reactants? What are the products? What powers or fuels each reaction?

Why have so many plants developed broad, flattened leaves? What is heliotropism?

If photosynthesis is to occur at all, the plant must be able to intercept light. The better a plant is in intercepting the light, the greater opportunities the plant has to produce food. Why have so many plants developed broad, flattened leaves? What is heliotropism, and how does it make plants more efficient? What are sleep mo

Photosynthesis

A) Name and describe the major reactions and sites of reactions of photosynthesis. b) State the relationships of these reactions. c) Include a definition and brief discussion of C3 and C4 plants.

Effect of Light Intensity on Photosynthesis: Lab Experiment

Design/carry out and REPORT on the investigation of a question you originate that relates to the effect of one of the factors affecting photosynthesis/ respiration in a specific plant species. Complete this using the "pop bottle terrarium" model BE SURE TO RELATE HOW THE INFORMATION GAINED HERE COULD HELP INFORM GROWERS OF PLANT

Photosynthesis

If photosystem II produces ATP, why do plants need mitochondria? How is ATP generated by the light reactions used?

Photosynthesis in Cyanobacteria is oxygenic. Why ?

Photosynthesis, in general, is accompained by the release of oxygen. Prokaryotes are exception to it as a typical bacterial photosynthesis is anoxygenic (oxygen is not released). However, cyanobacteria is an exception to the bacterial photosynthesis as it is oxygenic.

Atmospheric Change

A. How would the composition of the earth's atmosphere change if green plants and other autotrophs disappeared? Explain why in term of your knowledge of photosynthesis. B. How would animal life be affected by this atmospheric change? Explain why in terms of your knowledge of cellular respiration.

Articles on acidity and photosynthesis

I recently did an experiment testing photosynthesis in soybean plants after simulated acid rain. We had three treatments one was a control which recieved no acid solution, a soil pH treatment in which the acidic solution was only added to the soil and a foliar pH treatment in which, only the leaves were sprayed with an acidic

Photosynthesis in Autumn

Question: how do leaves which are normally green but turn color in autumn carry out photosynthesis in autumn?

Nitrogen Fixation: Nodulation Capacities

When comparing nodule specific nitrogenase activities in control and nitrate treated plants at 20% oxygen, why is it necessary to express nitrogenase activity per gram fresh weight of nodule tissue? Ideas are presented.

Working with Nitrogen Fixation

Why does EAC have a maximum value of 0.75? What would be the likely effect on plant yield if this value declined to a very low level?

Carboxylation Efficiencies

Why would the carboxylation efficiency in C4 plants be higher than the carboxylation efficiency in C3 plants?

CO2 saturation point

At the CO2 saturation point, is light supply the major factor limiting photosynthesis? How could you test this?

Description

I need a description of the general events of the light reaction and the Calvin cycle in AUTOTROPHS. I am interested in the sequence of events for the two. Thank you