Problem: I can use this background: In the U.S., the majority of electricity is produced by burning coal or other fossil fuels. This causes air pollution, acid rain, and global warming. Fossil fuels are also limited and may eventually run out. Like fossil fuels, radioactive elements are limited. In fact, they are relatively rare, so they could run out sooner rather than later. On the other hand, nuclear fission does not release air pollution or cause the other environmental problems associated with burning fossil fuels. This is the major advantage of using nuclear fission as a source of energy. Now, I have a new situation: Two sister cities used different methods to produce electricity. London used fossil fuels, while Edmonton use entirely hydro power to generate energy. Answer this question please: Which city causes less global warming?

A: Edmonton

Problem: I can use this background: A large log placed in a fire will burn relatively slowly. If the same mass of wood were added to the fire in the form of small twigs, they would burn much more quickly. This is because the twigs provide a greater surface area than the log does. An increase in the surface area of a reactant increases the rate of a reaction. Surface area is larger when a given amount of a solid is present as smaller particles. A powdered reactant has a greater surface area than the same reactant as a solid chunk. In order to increase the surface area of a substance, it may be ground into smaller particles or dissolved into a liquid. In solution, the dissolved particles are separated from each other and will react more quickly with other reactants. Now, I have a new situation: Two friends went camping and made a fire each. Bill used a few large logs while Tim used kindlings, wood chips and sawdust. they both brought the same volume of wood. Answer this question please: Which friend made a fire that burned hotter?

A: Tim

Problem: I can use this background: As a cell grows, its volume increases more quickly than its surface area. If a cell was to get very large, the small surface area would not allow enough nutrients to enter the cell quickly enough for the cell's needs. This idea is explained in Figure below . However, large cells have a way of dealing with some size challenges. Big cells, such as some white blood cells, often grow more nuclei so that they can supply enough proteins and RNA for the cell's requirements. Large, metabolically active cells often have lots of cell protrusions, resulting in many folds throughout the membrane. These folds increase the surface area available for transport of materials into or out of the cell. Such cell types are found lining your small intestine, where they absorb nutrients from your food through protrusions called microvilli . Now, I have a new situation: There are two cells inside a Petri dish in a laboratory, cell X and cell Z. These cells are from the same organism, but have different characteristics. For example, cell Z is smaller than cell X. Furthermore, scientists studying the two cells have recorded that cell X is more metabolically active than cell Z. Answer this question please: Which cell has more nuclei?

A: cell X

Problem: I can use this background: Old age begins in the mid-60s and lasts until the end of life. Many people over 65 have retired from work, freeing up their time for hobbies, grandchildren, and other interests. Stamina, strength, reflex time, and the senses all decline during old age, and the number of brain cells decreases as well. The immune system becomes less efficient, increasing the risk of serious illnesses such as cancer and pneumonia. Diseases such as Alzheimer's disease that cause loss of mental function also become more common. Now, I have a new situation: Mary and Ann met after a long time. Mary was 70 and she was Ann's aunt. She had a number of health problems. Ann was 52 and quite healthy. Answer this question please: Which woman freed up more time for her grandchildren?

A:
Mary