Variables: The variables that might affect the rate of photosynthesis in this experiment are: Temperature: When the temperature rises so does the rate of photosynthesis; this is because as the temperature around the plant rises the enzymes controlling photosynthesis inside the chloroplasts heat up and start moving around faster, the fast moving molecules collide with other fast moving enzymes causing them to react....

DCPIP is a dark blue solution that becomes lighter as it is reduced.

Photosynthesis is important because animals eat food, as it is a source of energy.

Hill Reaction | Photosynthesis | Redox

The diagram below shows a setup that may be useful. It really just show the connection of two things: a flask with a sidearm (maybe a Büchner flask) and a graduated glass syringe. The exact positioning is something you should determine. Glass syringes are precision-made with low friction between the plunger and the barrel (unlike plastic ones that have high friction). Your should have some in the chem lab and if not they are reasonably cheap (about $50 for a 100 mL one). You need to introduce a gas (eg CO2) into the flask and surround the flask with water in a beaker on a hotplate. As it slowly heats (I mean slowly, maybe 20°C to 80°C over 40 minutes) the gas expands and the syringe is pushed out. With the syringe on it's side there is no need to worry about the weight of the plunger. You could compare gases - oxygen, nitrogen, hydrogen for example.

takes place in the light dependent stage of photosynthesis ..

Oxygen is evolved during photosynthesis but the conditions for maximum reaction rate are intriguing. It can be affected by many things, including: sunlight - its intensity and wavelength, temperature, CO2 and O2 availability, water (which closes stomata and restricts CO2), and any factor that influences the production of chlorophyll, enzymes, or the energy carriers ATP and NADPH, such as pH and Mg2+ availability. You could test the effect of pH and temperature. It sure won't be linear but how well your prediction (hypothesis) and results agree will be interesting. You could also try light intensity. If you don't have a "luxmeter" to measure intensity you could take advantage of the fact that as you double the distance of the light source to the plant, the intensity is quartered (but you'd have to cut out daylight). There are a lot of variables to control and complex biochemical reactions to examine.

Photosynthesis mainly takes place in the palisade mesophyll cell in the leaves of plants.
Basically the boiling of chloroplasts and the decrease in light did have negative effects on the rate of photosynthesis.

Investigating the light dependent reaction in photosynthesis

A DCPIP method that has been trialled extensively features a phosphoric/acetic acid extracting solution. I have adapted this method and added sample calculations. It can be downloaded by clicking the link: . The one caution with DCPIP and the cause of so much misery amongst students is that DCPIP is not easy to dissolve; you need to leave it overnight and then decant and filter it the next day.

Introduction Photosynthesis occurs only in the presence of light, and takes place in the chloroplasts of green plant cells....

Photosynthesis | Photosynthesis | Photochemistry

CHAPTER 5- PHOTOSYNTHESIS (a) define the terms autotroph and heterotroph; (b) state that light energy is used during photosynthesis to produce complex organic molecules; (c) explain how respiration in plants and animals depends upon the products of photosynthesis; (d) state that in plants photosynthesis is a two-stage process taking place in chloroplasts; (e) explain, with the aid of diagrams and electron micrographs, how the structure of chloroplasts enables them to carry out their functions; (f) define the term photosynthetic pigment; (g) explain the importance of photosynthetic pigments in photosynthesis; (h) state that the light-dependent stage takes place in thylakoid membranes and that the light-independent stage takes place in the stroma; (i) outline how light energy is converted to chemical energy (ATP and reduced NADP) in the light-dependent stage (reference should be made to cyclic and non-cyclic photophosphorylation, but no biochemical detail is required); (j) explain the role of water in the light-dependent stage; (k) outline how the products of the light-dependent stage are used in the light-independent stage (Calvin cycle) to produce triose phosphate (TP) (reference should be made to ribulose bisphosphate (RuBP), ribulose bisphosphate carboxylase (rubisco) and glycerate 3-phosphate (GP), but no other biochemical detail is required); (l) explain the role of carbon dioxide in the light-independent stage (Calvin cycle); (m) state that TP can be used to make carbohydrates, lipids and amino acids; (n) state that most TP is recycled to RuBP; (o) describe the effect on the rate of photosynthesis, and on levels of GP, RuBP and TP, of changing carbon dioxide concentration, light intensity and temperature; (p) discuss limiting factors in photosynthesis with reference to carbon dioxide concentration, light intensity and temperature; (q) describe how to investigate experimentally the factors that affect the rate of photosynthesis (HSW3).

As plants respire both night and day this starch is often used up during the night when photosynthesis cannot take place....

and light intensity on photosynthetic ..

Our experiment was designed to determine whether boiling and decrease in light will have negative effects on the rate of photosynthesis in chloroplasts.