Question

Study the graph which shows results of three different experiments P, Q and R.

Now compare curves Q and R and answer the following question:
Which factor has been altered to produce the differences you can see between two curves?

• A. CO${}_2$ concentration
• B. Temperature
• C. Both A and B
• D. None of the above

Answer 1

The correct option is A CO${}_2$ concentration

An optimum temperature ranging from 25${}^o$C to 35${}^o$C is required for a good rate. At temperatures around 0${}^o$C, the enzymes stop working and at very high temperatures the enzymes are denatured. Since, both the stages of photosynthesis require enzyme activity, the temperature has an affect on the rate of photosynthesis. In the atmosphere, the concentration of carbon dioxide ranges from .03 to .04 %. However, it is found that 0.1% of carbon dioxide in the atmosphere increases the rate of photosynthesis significantly. If we compare curve Q and R, the temperature at which it showed the curve was same in both the conditions. But, the concentration of CO${}_2$ is less in curve Q than curve R, which acts as limiting factor in curve Q.

So, the correct answer is option A.