[Q]: I read this background article the other day: The Human Immunodeficiency Virus ( HIV ) is the virus that causes Acquired Immunodeficiency Syndrome ( AIDS ). Most researchers believe that the HIV originated in sub-Saharan Africa during the 20th century. HIV is transmitted by sexual contact and by contact with infected bodily fluids, such as blood, semen, breast milk, and vaginal secretions. It is also passed from mother to fetus. HIV is now a pandemic , with an estimated (as of 2008) 38.6 million people now living with the disease worldwide. It is estimated that AIDS has killed more than 25 million people since it was first recognized in 1981. For further information about HIV/AIDS, see the CDC (Centers for Disease Control and Prevention) web site at http://www.cdc.gov/hiv/resources/factsheets/ . I am facing a new situation today: Dean and Paul both went to volunteered in Africa. They had a blood test when they came back. Paul had been infected with the HIV virus while Dean was healthy and clean. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which friend has a virus that is transmitted by contact with infected breast milk?
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[A]: Paul
input: Please answer the following: I read this background article the other day: When humans dig up and use fossil fuels, we have an impact on the carbon cycle ( Figure below ). This carbon is not recycled until it is used by humans. The burning of fossil fuels releases more carbon dioxide into the atmosphere than is used by photosynthesis. So, there is more carbon dioxide entering the atmosphere than is coming out of it. Carbon dioxide is known as a greenhouse gas , since it lets in light energy but does not let heat escape, much like the panes of a greenhouse. The increase of greenhouse gasses in the atmosphere is contributing to a global rise in Earth's temperature, known as global warming or global climate change. I am facing a new situation today: Space explorers, that launched from Earth, just encountered a new planet several light years away. This planet is almost an exact copy of Earth, but it is currently uninhabited by intelligent life. Upon landing, the explorers name the planet Caprica and begin learning as much as they can. They discover that the species on this Caprica are nearly all the same as on Earth, and even most of the topography looks the same. However, the main difference is that humans never evolved here. For this reason, there are no cities or cars or factories to burn up fossil fuels. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Does Earth need more or less photosynthesis than Caprica
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output: more
Please answer this: I read this background article the other day: 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. I am facing a new situation today: 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. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which woman had a more efficient immune system?
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Answer: Ann
Problem: I read this background article the other day: Antifreeze could also be called "antiboil" because it also raises the boiling point of the water in a car radiator. Hot weather combined with a hot engine can easily raise the temperature of the water in the radiator above 100 C, which is the boiling point of pure water. If the water boils, it could cause the engine to overheat and become seriously damaged. However, if antifreeze has been added to the water, the boiling point is much higher. For example a 50 percent antifreeze solution has a boiling point of 129 C. Unless the water gets hotter than this, it won't boil and ruin the engine. I am facing a new situation today: Alex and Bob both took their cars to a mechanic because they were having engine troubles. The mechanic decided that both need the water in their radiator replaced. The mechanic added a large amount of antifreeze to the water he put into Alex's radiator. Because he wanted to save money, the mechanic only added a small amount of antifreeze to the water he placed into Bob's radiator. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which person's engine, Alex's or Bob's, is less at risk of becoming damaged if it becomes very hot?

A: Alex's
Problem: Given the question: I read this background article the other day: Sand mining is a direct cause of erosion, and impacts the local wildlife.[2] Various animals depend on sandy beaches for nesting clutches, and mining has led to the near extinction of gharials (a species of crocodile) in India. Disturbance of underwater and coastal sand causes turbidity in the water, which is harmful for organisms like coral that need sunlight. It can also destroy fisheries, financially harming their operators. Removal of physical coastal barriers, such as dunes, sometimes leads to flooding of beachside communities, and the destruction of picturesque beaches causes tourism to dissipate. Sand mining is regulated by law in many places, but is often done illegally.[3] Globally, it is a $70 billion industry, with sand selling at up to $90 per cubic yard.[4] I am facing a new situation today: Sand mining in the north coastal region was stopped 20 years ago, but it still continues to this day in the south region. Both fishing communities there are still prosperous, but the southern one had a couple of bad years, with fish and other marine wildlife becoming more scarce. The southern beach had erosion problems as well. The northern beach recovered, and is suitable for tourism. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which region has a higher water turbidity?
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The answer is:
southern
Problem: I read this background article the other day: To determine the concentration of an acid in an aqueous solution, an acid-base titration is commonly performed. A strong base solution with a known concentration, usually NaOH or KOH, is added to neutralize the acid solution according to the color change of the indicator with the amount of base added.[7] The titration curve of an acid titrated by a base has two axes, with the base volume on the x-axis and the solution's pH value on the y-axis. The pH of the solution always goes up as the base is added to the solution. I am facing a new situation today: Due to increased carbon dioxide in the atmosphere more an more carbon dioxide is mixing with ocean water - thus increasing the acidity of the world's oceans. Rob is a climate scientist. He is measuring the acidity of the Atlantic ocean and the Pacific Ocean. To determine ocean water acidity he performed an acid-base titration. His conclusion is that Atlantic Ocean's acidity reached higher level than Pacific Ocean's acidity. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: In which ocean's acidity test Rob would have to add less base, Atlantic Ocean or Pacific ocean?

A:
Pacific Ocean