Written Response

Why have conservationists been particularly interested in the restoration of carnivore populations?

Carnivores often regulate the size of herbivore populations. The loss of carnivores can create a trophic cascade in which the population of herbivores increase, resulting in the overconsumption of primary producers. Taking wolves as an example, when they were taken out of the Yellowstone National Park due to them being considered a threat to the deer and elk, which were more desirable species. Since they were predators of the deer and elk, once they were gone, the population of deer and elk increased. This change was connected to the decline of plants, like aspen, cottonwood, and willow.

The high-energy end of the electromagnetic spectrum (gamma rays, x-rays, and ultraviolet) are damaging to living organisms. Why?

Gamma rays, x-rays, and UV lights have wavelengths that are shorter than those of visible light. Their photons pack energy sufficient to disrupt the bonds in many organic molecules. So these forms of radiation are generally harmful to living systems.

Think about the analogy of putting Earth's history into a 24-hour day. Why is it so shocking that humans have caused so much change to the planet?

If the Earth's history were put into a 24-hour day, the human population would have only been on earth for 0.04 seconds of that 24-hour day. The amount of change and destruction that man has made in that short amount of time, is like nothing that has ever happened in the 23 hours, 59 minutes, and 59.96 seconds that earth has existed. Mass deforestation, pollution, climate change, over population has been consistent throughout our 0,04 seconds on Earth.

List two lines of evidence for evolution and explain why they support the idea that all life has an original universal common ancestor.

One line of evidence for evolution is homologous structures, which is body parts of similar origin, structure, and development but adapted for different functions. Another line of evidence is vestigial organs, which is reduced or useless structures in plants or animals that may have served a purpose in early ancestors (human appendix, human tail). The idea of all life has an original universal common ancestor is supported because of early embryonic development of certain species is very similar.

What is the source of the energy that moves Earth's tectonic plates?

The earth's crust is broken into pieces that float on top of the mantle (tectonic plates), that aren't fixed but slowly move in relation to each other. Continents are embedded in some of these plates. Energy from convection currents slowly stir the plastic materials in the mantle, the plates also move.

Why is the number of people that the world can support in a sustainable fashion considered to be much lower than the global carrying capacity?

The well being of individuals within a population at carrying capacity is considered worse than that experience by individuals in a population that is well below its carrying capacity. The population that the world can support in a sustainable fashion is lower than the global carrying capacity because our resources on Earth are very limited. If we were to reach the Earth's carrying capacity, we would run out of resources and individual's well being would be at a stake.

In what ways does deforestation contribute to the increase greenhouse gases in the atmosphere?

What the wood is used for contributes to the increase greenhouse gases in the atmosphere. More than half of the wood harvested from deforestation is burned for fuel and made into charcoal. Most prominent in developing countries, their main source of energy comes from wood and burning the wood releases pollutants, like carbon monoxide. The production of paper contributes as well since the chemicals used in the process is a source of air pollution.

Water pollution has a devastating effect on stream, lake, and ocean ecosystems. Give three examples of problems associated with pollution in these systems.

a. Example one: Pollution has devastated the biodiversity of many streams. Filter-feeding animals in the streams are particularly sensitive to pollutants, causing their gills to clog. b. Example two: "Streams carry nutrients from stormwater, factories, and farms to lakes, where they accumulate in the water and sediments. Eutrophication, the enrichment of bodies of water with excess nutrients such as nitrogen and phosphorus, results in the rapid growth of populations of certain species of algae, with harmful consequences for the ecosystem. c. Example three: "The effects of pollution are particularly significant in the waters that drain into the ocean. Streams and estuaries transport nutrients from agricultural runoff and urban storm water into coastal waters. There, those nutrients boost the primary production of algae, resulting in a "bloom," a large often colorful accumulation of organic matter. As bacteria decompose this organic matter, they deplete the oxygen dissolved in the surrounding ocean water, creating dead zones (regions of very low oxygen in which few marine animals can survive).