If a solution has a higher concentration of hydronium ions than pure water, it has a pH lower than 7. A solution with a pH lower than 7 is called an acid . As the hydronium ion concentration increases, the pH value decreases. Therefore, the more acidic a solution is, the lower its pH value is. Did you ever taste vinegar? Like other acids, it tastes sour. Stronger acids can be harmful to organisms. For example, stomach acid would eat through the stomach if it were not lined with a layer of mucus. Strong acids can also damage materials, even hard materials such as glass. Mike is studying chemistry for his exam. Today, he is studying the properties of acids. He picks up an acid solution that he labels as solution A. To compare it with another solution he chooses a solution that is not an acid. He labels it as solution B. Would solution B have higher or lower pH value than solution A?
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Answer: higher

Machines make work easier by increasing the amount of force that is applied, increasing the distance over which the force is applied, or changing the direction in which the force is applied. Contrary to popular belief, machines do not increase the amount of work that is done. They just change how the work is done. So if a machine increases the force applied, it must apply the force over a shorter distance. Similarly, if a machine increases the distance over which the force is applied, it must apply less force. John wanted to invent a machine. To that end, he devised an experiment in which he used three components, comp A, comp B, and comp C. Comp A was a machine that applied force over a shorter distance. Comp B was also a machine, but it applied force over a longer distance. Comp C was not a machine. Would comp C less likely or more likely make work easier than comp A?
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Answer: less likely

Prokaryotes have a different way to increase genetic variation. It's called genetic transfer or bacterial conjugation . It can occur in two ways. One way is when cells "grab" stray pieces of DNA from their environment. The other way is when cells directly exchange DNA (usually plasmids) with other cells. For example, as shown in Figure below , the donor cell makes a structure called an F pilus , or sex pilus. The F pilus attaches one cell to another cell. The membranes of the two cells merge and genetic material, usually a plasmid , moves into the recipient cell. Genetic transfer makes bacteria very useful in biotechnology. It can be used to create bacterial cells that carry new genes. Two researches studied living organisms, Joe studied eukaryotes, while Bill studied prokaryotes. They were fascinated by genetic variation. Which researcher observed more membranes of two cells merging?
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Answer:
Bill