This is due to the light reaction of photosynthesis, which splits the water molecule and releases the oxygen in the process.
The sugar would be radioactive in the example where the plant was supplies carbon dioxide with radioactive oxygen. This is a result of the Calvin cycle, which uses the carbon dioxide to process into sugar.
Question 2: Some animal species can reproduce either asexually or sexually depending on the state of the environment. Asexual reproduction tends to occur in stable, favorable environments; sexual reproduction is more common in unstable or unfavorable circumstances. Discuss the advantages or disadvantages this pattern might have on the survival of the species in an evolutionary sense or on survival of individuals.
Answer 2: Asexual reproduction has the advantage of creating many offspring that are generally mature plants and not as frail as sexual seedlings. They reproduce easily and efficiently and are able to cover a habitat and reduce competition from other species. However, because they are essentially clones, they are sensitive to adverse environments such as pathogens and disease, which could wipe out the entire stand.
Sexual plants, dependent on seeds, have the disadvantage of producing seeds which must germinate and grow. This requires ideal conditions to establish new plants.