Answer the following question given this paragraph: Elements are substances that cannot be broken down into simpler substances with different properties. Q: What are substances that cannot be broken down into simpler substances with different properties called? Choices: - atoms - compounds - molecules - elements A:
elements

Answer the following question given this paragraph: Flatworms have a mesoderm cell layer and simple organ systems. They also show cephalization and bilateral symmetry. Q: What type of cell layer do flatworms have? Choices: - epidermis - cuticle - endoderm - mesoderm A:
mesoderm

Answer the following question given this paragraph: Scientists do the same thing when they classify , or put into categories, living things. Scientists classify organisms not only by their physical features, but also by how closely related they are. Lions and tigers look like each other more than they look like bears, but are lions and tigers related? Evolutionarily speaking, yes. Evolution is the change in a species over time. Lions and tigers both evolved from a common ancestor. So it turns out that the two cats are actually more closely related to each other than to bears. How an organism looks and how it is related to other organisms determines how it is classified. Q: What is the change in a species over time? Choices: - variation - phenomenon - transformation - evolution A:
evolution

Answer the following question given this paragraph: Air pollution may also cause acid rain. This is rain that is more acidic (has a lower pH) than normal rain. Acids form in the atmosphere when nitrogen and sulfur oxides mix with water in air. Nitrogen and sulfur oxides come mainly from motor vehicle exhaust and coal burning. Q: Acid rain may be caused by what? Choices: - hurricanes - water pollution - volcanos - air pollution A:
air pollution