*Question*
Answer the following question given this paragraph: Discussion for (a) This value is the net work done on the package. The person actually does more work than this, because friction opposes the motion. Friction does negative work and removes some of the energy the person expends and converts it to thermal energy. The net work equals the sum of the work done by each individual force. Strategy and Concept for (b) The forces acting on the package are gravity, the normal force, the force of friction, and the applied force. The normal force and force of gravity are each perpendicular to the displacement, and therefore do no work. Solution for (b) The applied force does work. Q: Friction does negative work and removes some of the energy the person expends and converts it to which kind of energy? Choices: - erosion - hydro - evaporation - thermal A:
**Answer**
thermal

*Question*
Answer the following question given this paragraph: Competition is a relationship between living things that depend on the same resources. Q: What kind of relationship exists between living things that depend on the same resources? Choices: - parasitic - symbiotic - antagonistic - competition A:
**Answer**
competition

*Question*
Answer the following question given this paragraph: Complexing agents that tie up metal ions are also used as drugs. British Anti-Lewisite (BAL), HSCH2CH(SH)CH2OH, is a drug developed during World War I as an antidote for the arsenic-based war gas Lewisite. BAL is now used to treat poisoning by heavy metals, such as arsenic, mercury, thallium, and chromium. The drug is a ligand and functions by making a water-soluble chelate of the metal; the kidneys eliminate this metal chelate (Figure 19.31). Another polydentate ligand, enterobactin, which is isolated from certain bacteria, is used to form complexes of iron and thereby to control the severe iron buildup found in patients suffering from blood diseases such as Cooley's anemia, who require frequent transfusions. As the transfused blood breaks down, the usual metabolic processes that remove iron are overloaded, and excess iron can build up to fatal levels. Enterobactin forms a watersoluble complex with excess iron, and the body can safely eliminate this complex. Q: How does consuming enterobactin help our body? Choices: - builds excess iron - eliminates excess fat - eliminates excess oxygen - eliminates excess iron A:
**Answer**
eliminates excess iron

*Question*
Answer the following question given this paragraph: Chemicals that are applied to farm fields include fertilizers and pesticides. Excess chemicals can be picked up by rainwater. The chemicals can end up in streams, ponds, lakes, or the ocean. Dissolved fertilizer causes tremendous numbers of water plants and algae to grow. This can lead to dead zones where nothing can live in lakes or the coastal oceans. Q: Dissolved fertilizer can ultimately lead to the creation of what in lakes or coastal oceans, which means a place where nothing can live? Choices: - extinction zone - deceased zone - hydrothermal vent - dead zone A:
**Answer**
dead zone