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Online Unit 4 quiz

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Department
Biology
Course
BIOL 1070
Professor
Wright& Newmaster
Semester
Fall

Description
Unit 8 Test An Arctic Ecosystem Rising atmospheric CO le2els from burning fossil fuels and other anthropogenic activity contributes to a warming of the Earth. Rising atmospheric CO levels from burning fossil fuels and other anthropogenic 2 activity therefore contributes to a warming of the Earth. st The North Pole may become up to 8°C warmer by the end of the 21 century unless we slow down greenhouse gas emissions. As arctic snow and ice melt, the darker land and ocean surfaces that are revealed absorb more of the sun’s energy, increasing arctic warming. In the arctic, a greater fraction of the extra energy received at the surface due to increasing concentrations of greenhouse gases goes directly into warming the atmosphere, whereas in the tropics, a greater fraction goes into evaporation. The depth of the atmospheric layer that has to warm in order to cause warming of near –surface air is much shallower in the arctic than in the tropics, resulting in a larger arctic temperature increase. As warming reduces the extent of sea ice, solar heat absorbed by the oceans in the summer is more easily transferred to the atmosphere in the winter, making the air temperature warmer than it would be otherwise. Because heat is transported to the arctic by the atmosphere and oceans, alterations in their circulation patterns can also increase arctic warming. The sub-Arctic regions of Canada (e.g., Churchill, Manitoba) contain a wide variety of both aquatic and terrestrial ecosystems, each characterized by different abiotic and biotic factors. In the high Arctic, near the communities of Resolute and Devon Island, much of the terrestrial environment is dominated by tundra. However, even at very high latitudes, there are both freshwater (rivers, ponds, lakes) and marine (Arctic ocean) habitats. Aquatic Animals A distinguishing feature of Arctic aquatic ecosystems is ice. Marine mammals that need to maintain a 37 degree body temp have a thick layer of insulating blubber just under the skin. Animals that generate their own internal heat through metabolism are called endotherms (meaning “inside heat”). For the most part, this is restricted to the so-called “warm-blooded” vertebrates — that is, mammals and birds. Unlike mammals and birds, fishes do not regulate their body temperatures internally, so they usually have the same internal temperature as the surrounding water. Animals such as fishes (and amphibians, reptiles, and invertebrates) that rely on environmental sources of heat are called ectotherms (meaning “outside heat”). Water breathing animals (e.g. molluscs, crustaceans, fish) have a gill structure that brings blood to an interface with the water (external environment) and the blood (internal environment), with a thin layer of gill cells in between. Any heat generated through metabolic processes is quickly lost at the gills, so that blood temperature is equal to the temperature of the external or ambient environment. Terrestrial Animals The north has been called “the land of the midnight sun” because the sun does not set at summer solstice, and at winter solstice the sun does not climb above the horizon. Some animals hibernate over the winter, while some stay active and search for scarce food. Some ectothermic animals, by contrast, can’t avoid freezing and survive numerous freeze-thaw cycles over many years (e.g., Woolly Caterpillar). Arctic
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