Problem: 
Q: Answer the following question given this paragraph:   Lipids are a class of biochemical compounds that living things use to store energy. Types of lipids include fats and oils.   Q: What are a class of biochemical compounds that living things use to store energy?   A:
Answer: lipids
Problem: 
Q: Answer the following question given this paragraph:   Life is complex, and there are millions of species alive today. Many millions more lived in the past and then went extinct. Organisms include microscopic, single-celled organisms. They also include complex, multicellular animals such as you. Clearly, life science is a huge science. That’s why a life scientist usually specializes in just one field within life science. Dr. Smith, for example, specializes in ecology. You can see the focus of ecology and several other life science fields in Table below . Click on the links provided if you want to learn about careers in these fields.   Q: What do you call a species that has died out in the past?   A:
Answer: extinct
Problem: 
Q: Answer the following question given this paragraph:   The use of nuclear fusion for energy has several pros. Unlike nuclear fission, which involves dangerous radioisotopes, nuclear fusion involves hydrogen and helium. These elements are harmless. Hydrogen is also very plentiful. There is a huge amount of hydrogen in ocean water. The hydrogen in just a gallon of water could produce as much energy by nuclear fusion as burning 1,140 liters (300 gallons) of gasoline! The hydrogen in the oceans would generate enough energy to supply all the world’s people for a very long time.   Q: Unlike nuclear fission, which involves dangerous radioisotopes, nuclear fusion involves what two harmless elements?   A:
Answer:
hydrogen and helium