A doctor tested two people for HIV. Tom had the virus in his blood, while Nick didn't have HIV, he was healthy. Tom has apparently had the virus for 20 years. Which person didn't have the ability of the immune system to defend the body decreasing? Hint: As time passes, the number of HIV copies keeps increasing, while the number of helper T cells keeps decreasing. The graph in Figure below shows how the number of T cells typically declines over a period of many years following the initial HIV infection. As the number of T cells decreases, so does the ability of the immune system to defend the body. As a result, an HIV-infected person develops frequent infections. Medicines can slow down the virus but not get rid of it, so there is no cure at present for HIV infections or AIDS. There also is no vaccine to immunize people against HIV infection, but scientists are working to develop one.
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Answer: Nick

David wants to categorize animals according to the sound waves they can hear. Eventually, he was able to categorize them in three different groups, group A, group B, and group C. He placed the animals that can only hear ifrasound in group A. Then he placed the animals that are only able to hear the same frequency of sound waves as humans do in group B. The last group of animals were able to hear only ultrasound. He placed them in group C. Would group B able to hear higher or lower frequency than group A? Hint: The frequency of sound waves is measured in hertz (Hz), or the number of waves that pass a fixed point in a second. Human beings can normally hear sounds with a frequency between about 20 Hz and 20,000 Hz. Sounds with frequencies below 20 hertz are called infrasound . Sounds with frequencies above 20,000 hertz are called ultrasound . Some other animals can hear sounds in the ultrasound range. For example, dogs can hear sounds with frequencies as high as 50,000 Hz. You may have seen special whistles that dogs but not people can hear. The whistles produce a sound with a frequency too high for the human ear to detect. Other animals can hear even higher-frequency sounds. Bats, for example, can hear sounds with frequencies higher than 100,000 Hz.
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Answer: higher

Ronaldo and Jeff are two college roommates that have similar body structure and similar physical activity levels. Ronaldo is a nutrition enthusiast and eats a diet with appropriately low amounts of fat and cholesterol. Jeff, on the other hand, doesn't really care about nutrition at all. He eats whatever he wants, whenever he wants, and as a result he consumes a diet with an inappropriately high amount of fat and cholesterol. Who is more likely to be at risk for cardiovascular disease? Hint: Although some lipids in the diet are essential, excess dietary lipids can be harmful. Because lipids are very high in energy, eating too many may lead to unhealthy weight gain. A high-fat diet may also increase lipid levels in the blood. This, in turn, can increase the risk for health problems such as cardiovascular disease. The dietary lipids of most concern are saturated fatty acids, trans fats, and cholesterol. For example, cholesterol is the lipid mainly responsible for narrowing arteries and causing the disease atherosclerosis.
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Answer:
Jeff