Question

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.

Answer 1

(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".