Problem: Local hospital has launched a program to check if a patient has Retinitis. Resident ophthalmologist David is in charge of this program. In the first day of the program he checked two patients, patient A and patient B. The test result showed that patient A had Retinitis, but patient B did not have Retinitis. Then next day David checked two other patients, patient C and patient D. Patient C was 40 years old, but patient D was 80 years old. He found both patient C and D had Retinitis. Which patient would not have inflammation of retina, patient A or patient B? Hint: Retinitis is inflammation of the retina in the eye, which can permanently damage the retina and lead to blindness. The retina is the part of your eye that is also known as the "sensing tissue." Retinitis may be caused by a number of different infectious agents. Retinitis, also called Retinitis pigmentosa, has a prevalence of one in every 2,500-7,000 people. This condition is one of the leading causes that leads to blindness in patients in the age range of 2060 years old.

A: patient B

Problem: San Francisco and Baltimore both have large manufacturing and production industries and both border large oceans. San Francisco has been burning large amounts of fossil fuels recently to fuel their increased manufacturing and production of automobiles. Baltimore, however, has shifted to renewable resources recently, and as a result they have drastically decreased the amount of fossil fuels that are used to produce and manufacture steel. Oceans bordering which city, San Francisco or Baltimore, will absorb less carbon dioxide? Hint: Ocean acidification occurs when excess carbon dioxide in the atmosphere causes the oceans to become acidic. Burning fossil fuels has led to an increase in carbon dioxide in the atmosphere. This carbon dioxide is then absorbed by the oceans, which lowers the pH of the water. Ocean acidification can kill corals and shellfish. It may also cause marine organisms to reproduce less, which could harm other organisms in the food chain. As a result, there also may be fewer marine organisms for humans to consume.

A: Baltimore

Problem: Morgan and Jacob are conducting a chemical experiment involving sodium hydroxide. A key part of the reaction is ensuring that the sodium hydroxide is dissolved in water before adding the other materials. Morgan uses a pestle and mortar to crush the sodium hydroxide into a fine powder before adding it to his reaction mixture. Jacob doesn't feel like doing that because he is not very motivated, so he adds the sodium hydroxide in the form of large chunks. Who will be able to add the other materials to their reaction sooner? Hint: 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

A: Morgan

Problem: Two farmers sold their produce and milk on a large nearby market. John practiced organic farming and also produced organic milk, while Danny sold non-organic produce and milk. Which farmer sold fewer healthy and safe foods? Hint: As for the public health or food safety concern, organic foods are intended to be healthy, free of contaminations and free from agents that could cause human diseases. Organic milk is meant to have no chemical residues to consumers, and the restrictions on the use of antibiotics and chemicals in organic food production has the purpose to accomplish this goal. Although dairy cows in both organic and conventional farming practices can be exposed to pathogens, it has been shown that, because antibiotics are not permitted as a preventative measure in organic practices, there are far fewer antibiotic resistant pathogens on organic farms. This dramatically increases the efficacy of antibiotics when/if they are necessary.

A:
Danny