Q: What force holds planets in their orbits? Choices: - magnetism - centrifuge - Big Bang - gravity A:
gravity

Q: What is the name of the symbiotic relationship in which one species benefits while the other species is not affected? Choices: - pollenation - differentiation - mutualism - commensalism A:
commensalism

Q: Scientists think the solar system formed from a big cloud of gas and dust called what? Choices: - comet - supernova - Oort cloud - nebula A:
nebula

Q: What is the cause of behavioral difference between populations? Choices: - environmental factors - electromagnetic differences - genetic wavelengths - genetic differences A:
genetic differences