The lungs of mammals are unique in having alveoli . These are tiny, sac-like structures. Each alveolus is surrounded by a network of very small blood vessels (see Figure below ). Because there are millions of alveoli in each lung, they greatly increase the surface area for gas exchange between the lungs and bloodstream. Human lungs, for example, contain about 300 million alveoli. They give the lungs a total surface area for gas exchange of up to 90 square meters (968 square feet). That's about as much surface area as one side of a volleyball court! Two students learned about respiratory systems in animals. Dana learned more about mammalian lungs, while Barry learned more about the lungs of birds. Which student learned more about surface area for gas exchange between the lungs and bloodstream?
Ans: Dana

Greenhouse Effect: The solar energy reaching the surface of the Earth is concentrated in short wavelengths, which can easily penetrate the greenhouse gases, such as carbon dioxide and methane. The Earth, however, is cooler than the sun and it radiates its heat in the form of energy in the far infrared range. These longer wavelengths are partially absorbed by the greenhouse gases and some of the solar heat is returned to Earth. At a certain temperature these processes are in equilibrium and the surface temperature of the Earth is stable. However, if more greenhouse gases are put in the atmosphere the amount of trapped terrestrial radiation increases, leading to an increase in global temperature. Barb and Dee studied chemistry for a school project. After little debate they decided that Dee will study volatile gases, and Barb will study greenhouse gasses. Which girl studied less about carbon dioxide?
Ans: Dee

Alkali, or Alkaline, soils are clay soils with high pH (> 8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell[1] and difficult to clarify/settle. They derive their name from the alkali metal group of elements, to which sodium belongs, and which can induce basicity. Sometimes these soils are also referred to as alkaline sodic soils. Alkaline soils are basic, but not all basic soils are alkaline. Mike grew tomatoes on his parcel of land and so did John. Mike's attempt was very successful, because he adjusted the soil's pH to a viable level for growing vegetables, and John didn't. Both parcels had soils with lots of sodium carbonate in them. John's experiment failed. Which soil was more alkaline sodic?
Ans: John's

The temperature of a body of water directly affects the amount of dissolved oxygen it can hold. Following Henry's law, as water becomes warmer, oxygen becomes less soluble in it. This property leads to daily anoxic cycles on small geographic scales and seasonal cycles of anoxia on the larger scale. Thus, bodies of water are more vulnerable to anoxic conditions during warmest period of the day and during the summer months. This problem can be further exacerbated in the vicinity of industrial discharge where warm water used to cool machinery is less able to hold oxygen than the basin to which it is released. Dan visited Twin lakes every year. The interesting fact about them wast that, while Twin I had a very cold water all year, Twin II lake had very warm waters year round. Which body of water had fewer problems in the vicinity of industrial discharge ?
Ans: Twin I