Give reason a. fermentation stop when the concentration of alcohol reaches about 13 percent. b. the rate of photosynthesis decline in the presence on continuous light.

(a)Fermentation stop when the concentration of alcohol reaches about 13 percent.

Reason:

During the fermentation process ethanol is the end product. 'Yeast' is used as the leavening agent. At time when the concentration of alcohol reaches about 13%, alcohol (ethanol) produced is toxic enough to kill yeast. Yeast cause fermentation, so when it dies fermentation stops. (b) The rate of photosynthesis decline in the presence on continuous light.

Reason:

Photosynthesis is a process in which 'green plants' prepare food by utilizing carbon di oxide and water in the 'presence of sunlight' using chlorophyll and produce "oxygen as a by-product".When there is continuous light on plants there is accumulation of ATP (adenosine triphosphate) and NADPH2 (nicotine amide adenine dinucleotide phosphate) which might cause in "photo-oxidation of chlorophyll" and hence "rate of photosynthesis decreases".