Theories are a collection of scientific data that is generally accepted and reproducible. Theories are a result from several repeated experiments, but theories are not based on a single hypothesis. Several hypotheses are tested and appraised to become a well accepted theory. Theories may also be revised over time and can predict what may happen in the future. On the other hand, theories are not proven facts.
Having the haploid number of chromosomes allows the zygote to have the correct number. If gametes weren't haploid, every generation of organisms would have twice as many chromosomes as their parents. I hope my answer has come to your help. God bless and have a nice day ahead!
A. to find out if a hypothesis is correct.
The answer is because biology is easy and they're known around the world.
Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. While water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.