Q: What force holds planets in their orbits? Read this paragraph and choose the correct option from the provided answers: Planets are held in their orbits by the force of gravity. What would happen without gravity? Imagine that you are swinging a ball on a string in a circular motion. Now let go of the string. The ball will fly away from you in a straight line. It was the string pulling on the ball that kept the ball moving in a circle. The motion of a planet is very similar to the ball on a string. The force pulling the planet is the pull of gravity between the planet and the Sun. 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? Read this paragraph and choose the correct option from the provided answers: Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected. One species typically uses the other for a purpose other than food. For example, mites attach themselves to larger flying insects to get a "free ride. " Hermit crabs use the shells of dead snails for homes. Choices: - pollenation - differentiation - mutualism - commensalism A:
commensalism

Q: Scientists think the solar system formed from a big cloud of gas and dust called what? Read this paragraph and choose the correct option from the provided answers: Scientists think the solar system formed from a big cloud of gas and dust, called a nebula . This is the solar nebula hypothesis. The nebula was made mostly of hydrogen and helium. There were heavier elements too. Gravity caused the nebula to contract ( Figure below ). Choices: - comet - supernova - Oort cloud - nebula A:
nebula

Q: What is the cause of behavioral difference between populations? Read this paragraph and choose the correct option from the provided answers: Choices: - environmental factors - electromagnetic differences - genetic wavelengths - genetic differences A:
genetic differences