Like other succulent plants, most cacti<span> employ a special mechanism called "crassulacean acid metabolism" (CAM) as </span>part<span> of </span>photosynthesis<span>. Transpiration, during which carbon dioxide enters the plant and water escapes, </span>does<span> not </span>take place<span> during the day at the same time as </span>photosynthesis<span>, but instead </span>occurs<span> at night.</span>
. It can lead to changes in allele frequencies and the evolution oftraits.
Absolutely not!
Your hypothesis is your educated guess on how the experiment will go. If in the end of your experiment, you find that your hypothesis was not supported, that does not make you wrong.
I hope this helps!