*Question*
Answer the following question given this paragraph: Most of us are familiar with rusty iron: metal that has a dark red-brown scale that falls off an object, ultimately weakening it. Although we usually attribute rusting exclusively to iron, this process occurs with many materials. The more formal term for rusting is corrosion. Corrosion is defined as the disintegration of a material due to chemical reactions with other substances in the environment. In many cases, oxygen in the air causes the disintegration. Corrosion is not uniformly destructive. Although the corrosion of iron is generally considered bad, the corrosion of aluminum and copper forms a protective barrier on the surface of the metal, protecting it from further reaction with the environment. Having said that, it has been estimated that as much as 5% of expenditures in the United States apply to fixing problems caused by corrosion. The replacement of structures built with iron, steel, aluminum, and concrete must be performed regularly to keep these structures safe. As an example of what might happen, consider the story of the Silver Bridge on US Interstate 35, connecting West Virginia and Ohio. On December 15, 1967, the 39-year-old bridge collapsed, killing 46 people. The ultimate cause of the collapse was determined to be corrosion of a suspension chain on the Ohio side of the bridge. Corrosion is an example of the type of chemical reaction discussed in this chapter. Although we usually think of corrosion as bad, the reaction it typifies can actually be put to good use. One important type of chemical reaction is the oxidation-reduction reaction, also known as the redox reaction. Although we introduced redox reactions in - ball-ch04, - ball-ch04_s06, it is worth reviewing some basic concepts. Q: Exemplified by rusty iron, what process is defined as the disintegration of a material due to chemical reactions with other substances in the environment? Choices: - Metal Breakdown - magnesium - extraction - corrosion A:
**Answer**
corrosion

*Question*
Answer the following question given this paragraph: Plant Parasites and Pathogens The production of enough good-quality crops is essential to our existence. Plant diseases have ruined crops, bringing widespread famine. Most plant pathogens are fungi that cause tissue decay and eventual death of the host (Figure 13.25). In addition to destroying plant tissue directly, some plant pathogens spoil crops by producing potent toxins. Fungi are also responsible for food spoilage and the rotting of stored crops. For example, the fungus Claviceps purpurea causes ergot, a disease of cereal crops (especially of rye). Although the fungus reduces the yield of cereals, the effects of the ergot's alkaloid toxins on humans and animals are of much greater significance: In animals, the disease is referred to as ergotism. The most common signs and symptoms are convulsions, hallucination, gangrene, and loss of milk in cattle. The active ingredient of ergot is lysergic acid, which is a precursor of the drug LSD. Smuts, rusts, and powdery or downy mildew are other examples of common fungal pathogens that affect crops. Q: A type of what organism causes ergot, a disease that impacts crops directly and has more devastating effects on animals? Choices: - insects - bacteria - virus - fungus A:
**Answer**
fungus

*Question*
Answer the following question given this paragraph: Community Ecology A biological community consists of the different species within an area, typically a three-dimensional space, and the interactions within and among these species. Community ecologists are interested in the processes driving these interactions and their consequences. Questions about conspecific interactions often focus on competition among members of the same species for a limited resource. Ecologists also study interactions among various species; members of different species are called heterospecifics. Examples of heterospecific interactions include predation, parasitism, herbivory, competition, and pollination. These interactions can have regulating effects on population sizes and can impact ecological and evolutionary processes affecting diversity. For example, Karner blue butterfly larvae form mutualistic relationships with ants. Mutualism is a form of a longterm relationship that has coevolved between two species and from which each species benefits. For mutualism to exist between individual organisms, each species must receive some benefit from the other as a consequence of the relationship. Researchers have shown that there is an increase in the probability of survival when Karner blue butterfly larvae (caterpillars) are tended by ants. This might be because the larvae spend less time in each life stage when tended by ants, which provides an advantage for the larvae. Meanwhile, the Karner blue butterfly larvae secrete a carbohydraterich substance that is an important energy source for the ants. Both the Karner blue larvae and the ants benefit from their interaction. Q: What consists of the different species within an area? Choices: - abundant community - science community - contamination community - biological community A:
**Answer**
biological community

*Question*
Answer the following question given this paragraph: Metals such as iron are useful for many purposes because of their unique properties. For example, they can conduct electricity and bend without breaking. However, pure metals may be less useful than mixtures of metals with other elements. For example, adding a little carbon to iron makes it much stronger. This mixture is called steel. Steel is so strong that it can hold up huge bridges, like the one pictured above. Steel is also used to make skyscrapers, cargo ships, cars, and trains. Steel is an example of an alloy. Q: Adding carbon to iron makes what type of metal? Choices: - ions - titanium - plastic - steel A:
**Answer**
steel