*Question*
Answer the following question given this paragraph:   Figure 42.4 Interferons are cytokines that are released by a cell infected with a virus. Response of neighboring cells to interferon helps stem the infection.   Q: What are interferons?   Choices:  - T cells  - oncogenes  - pathogens  - cytokines  A:
**Answer**
cytokines

*Question*
Answer the following question given this paragraph:   When done regularly, aerobic activities, such as cycling, make the heart stronger. Other aerobic activities include mowing lawn, shoveling snow and cross country skiing.   Q: Cycling, shoveling snow and cross-country skiing are examples of what kind of heart-strengthening activity?   Choices:  - metabolism  - anaerobic  - exercise  - aerobic  A:
**Answer**
aerobic

*Question*
Answer the following question given this paragraph:   Life on Earth is based on carbon. A possible explanation is that no other element in the periodic table forms compounds that are so diverse in their chemistry and physical properties. Discuss the chemistry of carbon with regard to.   Q: What element on the periodic table forms the most diverse compounds?   Choices:  - helium  - oxygen  - hydrogen  - carbon  A:
**Answer**
carbon

*Question*
Answer the following question given this paragraph:   A related process to diffusion is the effusion. Effusion is the process of a confined gas escaping through a tiny hole in its container. Effusion can be observed by the fact that a helium-filled balloon will stop floating and sink to the floor after a day or so. This is because the helium gas effuses through tiny pores in the balloon. Both diffusion and effusion are related to the speed at which various gas molecules move. Gases that have a lower molar mass effuse and diffuse at a faster rate than gases that have a higher molar mass.   Q: Both diffusion and effusion are related to the speed at which what objects move?   Choices:  - electricity  - copper molecules  - solids  - gas molecules  A:
**Answer**
