Question: I have a new situation: Keith is an environmental scientist. He was studying the loss of ozone layer and its effect on different species. His data showed that in the beginning or twentieth century there were hardly any loss of ozone layer. He categorized that time period as time A. Further inquiry revealed that things didn't go well at the end of twentieth century - when there were severe loss of ozone layer. He categorized that time as time B. But I can use this background: Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. Its rate of loss has slowed with restrictions on pollutants, but it is still at risk. What is an answer for this question: Which perion would less likely see ocean food webs disrupted, time A or time B?
Answer: time A

Question: I have a new situation: Jill lives out in a peaceful quiet area with hardly any other people around. Next to her home is a calm peaceful river. The river doesn't have an official name that she is aware of, but her family has always called it River Treetop due to the large tree next to it. Also next to her house, there is a roaring river that runs for miles. The river is so loud that it can be hard to hear yourself think sometimes if you are sitting next to it. For this reason, Jill has always referred to the river as River Chaos. But I can use this background: The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater biodiversity than the slow moving water of pools. These distinctions form the basis for the division of rivers into upland and lowland rivers. The food base of streams within riparian forests is mostly derived from the trees, but wider streams and those that lack a canopy derive the majority of their food base from algae. Anadromous fish are also an important source of nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution and introduced species. A dam produces negative effects that continue down the watershed. The most important negative effects are the reduction of spring flooding, which damages wetlands, and the retention of sediment, which leads to loss of deltaic wetlands. What is an answer for this question: Which body of water is less concentrated with dissolved oxygen?
Answer: River Treetop

Question: I have a new situation: Mary's lake was full of fish, the lake's environment was very healthy. Mary stopped fishing on this lake five years ago and maintained it properly. Jane's lake had high fish mortality both from fishing and pollution, and disease from overstocking. But I can use this background: Fish mortality is a parameter used in fisheries population dynamics to account for the loss of fish in a fish stock through death. The mortality can be divided into two types: Natural mortality: the removal of fish from the stock due to causes not associated with fishing. Such causes can include disease, competition, cannibalism, old age, predation, pollution or any other natural factor that causes the death of fish. In fisheries models natural mortality is denoted by (M).[1] Fishing mortality: the removal of fish from the stock due to fishing activities using any fishing gear.[1] It is denoted by (F) in fisheries models. What is an answer for this question: Which lake had a higher natural mortality?
Answer:
Jane's