Maybe it’s because in order the get the same apple you breed more of that apple? It would take less time than natural selection since the genes of that certain apple may not appear for a few generations. If this makes any sense let me know because I’m just as confused as you are.
In photosynthesis experiment, the effect of the light will be observe during the starch production- thus you need to have a plant without a starch to observe if the starch is produced during photosynthesis. Letting the leaves of the plant deprived from light for 48 hours will be forced to use its reserved starch making the storage of the starch decrease.
Oxygen, water, some type of resources to build, and food to eat