In photosynthesis, water and carbon dioxide react in the presence of sunlight and chlorophyll to produce sugar and oxygen in plants. Explain why photosynthesis is not really a synthesis reaction.

is there multiple choice answers?

the volume increases

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.