Ques:Answer the following question given this paragraph: Antibodies also mark pathogens for destruction by phagocytic cells, such as macrophages or neutrophils, because phagocytic cells are highly attracted to macromolecules complexed with antibodies. Phagocytic enhancement by antibodies is called opsonization. In a process called complement fixation, IgM and IgG in serum bind to antigens and provide docking sites onto which sequential complement proteins can bind. The combination of antibodies and complement enhances opsonization even further and promotes rapid clearing of pathogens. Affinity, Avidity, and Cross Reactivity Not all antibodies bind with the same strength, specificity, and stability. In fact, antibodies exhibit different affinities (attraction) depending on the molecular complementarity between antigen and antibody molecules, as illustrated in Figure 42.25. An antibody with a higher affinity for a particular antigen would bind more strongly and stably, and thus would be expected to present a more challenging defense against the pathogen corresponding to the specific antigen. Q: Antibodies also mark pathogens for destruction by which cells? Choices: - interferons - leukocytes - platelets - phagocytic A:

Ans:phagocytic
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Ques:Answer the following question given this paragraph: Outdoor air pollution is made of chemical particles. When smoke or other pollutants enter the air, the particles found in the pollution mix with the air. Air is polluted when it contains many large toxic particles. Outdoor air pollution changes the natural characteristics of the atmosphere. Primary pollutants are added directly to the atmosphere. Fires add primary pollutants to the air. Particles released from the fire directly enter the air and cause pollution ( Figure below ). Burning of fossil fuels such as oil and coal is a major source of primary pollutants ( Figure below ). Q: A major source of primary pollutants is the burning of oil and coal, which are types of what? Choices: - erosion fuels - renewable fuels - greenhouse gases - fossil fuels A:

Ans:fossil fuels
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Ques:Answer the following question given this paragraph: Q: What are gymnosperms lacking compared to most angiosperms? Choices: - muscle elements - use elements - vascular elements - vessel elements A:

Ans:vessel elements
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Ques:Answer the following question given this paragraph: This is how ice wedging works. When liquid water changes into solid ice, it increases in volume. You see this when you fill an ice cube tray with water and put it in the freezer. The ice cubes go to a higher level in the tray than the water. You also may have seen this if you put a can of soda into the freezer so that it cools down quickly. If you leave the can in the freezer too long, the liquid expands so much that it bends or pops the can. (For the record, water is very unusual. Most substances get smaller when they change from a liquid to a solid. ). Q: Do most substances increase or decrease in size when they change from a liquid to a solid? Choices: - increase - stay the same - it is unable to be measured - decrease A:

Ans:
decrease
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