1. One way in which preserving biodiversity locally might have a global effect are if all internationally traded organisms (whether alive or dead) were monitored, regardless of whether they are currently listed as threatened. This would allow countries to identify emerging markets and act early enough to prevent depletion.
2. Habitat destruction and loss of species effect more than just one area because if one species in a habitat is diminished, then the predator of that animal is left with no food. The predator then must move to a new habitat to find food, completely messing up that habitat's food chain. This would also happen if the habitat had been affected by destruction of some kind.
3. Preserving biodiversity enhances the life of people by giving us more resources to use, mainly food, but also trees, water, and even clothing sometimes. It will also enhance the lives of future generations by providing enough resources, and even more than enough resources, for them to rely on.