Short Answer / Long Response Questions

Describe Commensalism:

A symbiosis in which one species benefits and the other is neither harmed nor benefitted

Marvin is stressed about waking up and making it on time to his Environmental Science midterm. He sets the alarm on his digital watch (to 1/100 of a second!) and arrives at 9:00:00.00 a.m. unfortunately, every other clock on campus reads about 9:10. Marvin is woefully late and misses ten minutes of the exam. What can be said about the accuracy and precision of Marvin's watch?

Accuracy - not very accurate Precision - very precise

Is a carrying capacity a fixed entity? Discuss the role of humans in regulating carrying capacity for the human species and in altering the carrying capacity for other species.

Carrying capacity is not a fixed entity. Carrying capacity is the number of people, other living organisms, or crops that an area can successfully support without degradation. Humans decide how many resources will be used up in an area which can directly affect other living organisms. For example, if humans use up all freshwater/groundwater in an area and move away this will affect all animals that rely on that water for nourishment.

The early atmosphere of the Earth had very little oxygen. Which organisms led to the rise of an oxygenated atmosphere?

Cyanobacteria, or blue algae

Under what conditions does a population follow an exponential growth curve? Please draw an exponential growth curve.

Exponential growth is achievable when resources available to a population are unlimited. This will result in population increasing by a constant percentage per unit time. This graph is J-Shaped

Is extinction natural? How has extinction rate changed over time? Why are extinction rates today different than in the past?

Extinction is a natural process. Extinction rates have risen higher than the background extinction rate during several mass extinction events during Earth's history. In the past 440 million years, there have been five major episodes of mass extinction. If current trends continue, the modern era may see the extinction of more than half of all species. While similar in scale to previous mass extinctions, today's ongoing mass extinction is different in two respects. First, humans are causing it. Second, humans will suffer as a result. "Anthropogenic Extinction" - human caused

Explain what positive and negative feedbacks are and how they affect the stability of a system. Please give an example of a positive and negative feedback dealing with water vapor in the Earth's climate system.

Negative Feedback Loop - an increase in output leads to a later decrease. An increase in solar radiation raises ocean temperature, resulting in more evaporation which produces more clouds. Positive Feedback Loop - drives the system towards an extreme. An increase in output leads to a further increase in the output. Water evaporates as a greenhouse gas which in turn increases the temperature of the atmosphere. Both cause outputs in a system to be routed back as inputs in a chain of cause and effect that results in a circuit or a loop.

What are the 4 R's in waste management? Give an example of how you can implement each of these R's

Reduce - Using a dish towel instead of paper towels Reuse - Reuse grocery bags for other purposes Recycle - Throw plastic bottles in the recycle bin Repair - Try to fix items and make them usable again instead of throwing them out and replacing them.

If a lake is very large and the flow of water into and out of the lake is very slow, what can we say about the residence time of water in the lake?

Residence time is high

Describe different types of age structures observed in countries around the world and how these age structures impact current and future social and economic conditions in these countries?

Rwanda's population pyramid is shown as a very fast growing country, most of the population is in the bottom age groups. Rwanda is only staring to begin industrialization on their economy, this will increase the average life expectancy of people living in Rwanda, and decrease child mortality rates due to improvements in medicine and sanitation.

What does species richness refer to?

Species richness is the number of different species represented in an ecological community

How does the total fertility rate (TFR) affect the population growth of a nation?

Total fertility rate reflects the number of children who would be born per woman, the higher the rate the faster population growth will be.

Owls and hawks prey on similar animals, but hawks hunt by day and owls hunt by night. What ecological principle is this an example of

niche differentiation