Given the background: Clouds on Earth are made of water vapor. Venus's clouds are a lot less pleasant. They are made of carbon dioxide, sulfur dioxide and large amounts of corrosive sulfuric acid! The atmosphere of Venus is so thick that the pressure on the surface of Venus is very high. In fact, it is 90 times greater than the pressure at Earth's surface! The thick atmosphere causes a strong greenhouse effect. As a result, Venus is the hottest planet. Even though it is farther from the Sun, Venus is much hotter even than Mercury. Temperatures at the surface reach 465C (860F). That's hot enough to melt lead! and the situation: Some students studied Earth's atmosphere in class. They also started studying Venus' atmosphere. They were fascinated by the subject and learned a lot. Answer the following question: Which planet has an atmosphere that is not toxic to humans, Venus or Earth?
Ans: Earth

Given the background: Protozoa generally feed by engulfing and digesting other organisms. As consumers, they have various roles in food chains and webs. Some are predators. They prey upon other single-celled organisms, such as bacteria. In fact, protozoa predators keep many bacterial populations under control. Other protozoa are herbivores. They graze on algae. Still others are decomposers. They consume dead organic matter. There are also parasitic protozoa that live in or on living hosts. For example, the protozoan that causes malaria lives inside a human host. Protozoa are also important food sources for many larger organisms, including insects and worms. and the situation: The students studied two ponds. Class A studied a pond filled with protozoa, while class B studied a pond with almost no protozoa. Answer the following question: Which class observed more engulfing and digesting of other organisms?
Ans: Class A

Given the background: When you add sugar to a cold drink, you may stir it to help the sugar dissolve. If you don't stir, the sugar may eventually dissolve, but it will take much longer. Stirring is one of several factors that affect how fast a solute dissolves in a solvent. Temperature is another factor. A solid solute dissolves faster at a higher temperature. For example, sugar dissolves faster in hot tea than in ice tea. A third factor that affects the rate of dissolving is the surface area of the solute. For example, if you put granulated sugar in a glass of ice tea, it will dissolve more quickly than the same amount of sugar in a cube. That's because granulated sugar has much more surface area than a cube of sugar. You can see videos of all three factors at these URLs and the situation: Greg is is a chef. Last night, he was in his kitchen preparing foods for the guests. First, he made some lemonade. In trial one he added some honey in it and stirred it, but in trial two he didn't stir it. Then he made some coffee. In trial three he added hot water in it, but in trial four he added cold water in it. Finally, he made some soup. In trial five he added fine grain salt in it, but in trial six he added coarse salt in it. Answer the following question: Would the coffee be prepared faster or slower in trial four than in trial three?
Ans: slower

Given the background: 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. and the situation: 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. Answer the following question: Would comp B increase or not increase the force applied compared to comp A?
Ans: not increase