Answer the following question given this paragraph: Buffers work well only for limited amounts of added strong acid or base. Once either solute is all reacted, the solution is no longer a buffer, and rapid changes in pH may occur. We say that a buffer has a certain capacity. Buffers that have more solute dissolved in them to start with have larger capacities, as might be expected. Human blood has a buffering system to minimize extreme changes in pH. One buffer in blood is based on the presence of HCO3 and H2CO3 [H2CO3 is another way to write CO2(aq)]. With this buffer present, even if some stomach acid were to find its way directly into the bloodstream, the change in the pH of blood would be minimal. Inside many of the body's cells, there is a buffering system based on phosphate ions. Q: Human blood has a buffering system to minimize extreme changes in what? Choices: - sodium level - calcium - ions - ph A:
ph

Answer the following question given this paragraph: Research is being done into alternative crops for biofuels. A very promising alternative is algae. Algae appears to be a better biofuel than corn. Algae is much easier to convert to a usable fuel. Growing algae requires much less land and energy than crops. Algae can be grown in locations that are not used for other things. For example, they can be grown in desert areas where food crops are not often grown. Corn must be grown where food crops are grown. This can reduce the land and water available for growing food. Algae can be fed agricultural and other waste, so valuable resources are not used. Much research is being done to bring these alternative fuels to market. Q: What is algae easier to covert into that corn is currently used for? Choices: - oil - food - sugar - fuel A:
fuel

Answer the following question given this paragraph: Muscles move the body by contracting against the skeleton. Q: What move the body by contracting against the skeleton? Choices: - hormones - tissues - nerves - muscles A:
muscles