1 . _____Living things are chemical systems. 99% of the molecular components of
ID: 161408 • Letter: 1
Question
1. _____Living things are chemical systems. 99% of the molecular components of living things consist of only 4 elements: carbon, hydrogen, oxygen and nitrogen, all of which are available within the biosphere. Of these four elements, one is the connector element that forms long chain molecules. The molecules of living things are built on this element. (1 point)
a. carbon b. silicon c. phosphorus d. nitrogen
2. What is the principal source of other vital elements (the remaining 1%) that are needed in much smaller quantities? (1 point)
3. In the Solar System, Earth is the only planet within the habitable zone, which is defined as that distance from the sun at which the temperature range allows liquid water at the surface. About 70% of the composition of living things is water (H2O).
ØList two reasons why liquid water is so essential to plants in particular. (2 points)
4. In a complex series of chemical reactions called photosynthesis, which materials are combined to produce a simple sugar called glucose? (1 point)
5. What does the process of photosynthesis add to the atmosphere that makes respiration possible? (1 point)
6. ________In respiration, which is essentially the opposite of photosynthesis, what happens to glucose? (1 point)
It is combined with carbon dioxide to produce proteins
It is combined with more glucose to produce starch and cellulose (wood)
It is combined with carbon dioxide to produce oxygen and water.
It is broken apart to release chemical energy in a form that the organism can use
7. What two important climate factors of the wet equatorial zone contribute most to the high biomass production per year in that region of the world? (2 points)
8. ____In nature, by what means is atmospheric nitrogen converted into biologically useful forms: (1 point) a. lightning and nitrogen-fixing bacteria
b. decomposition and respiration
c. digestive gases from grazing animals
d. none of the above
9. Artificial fertilizers work by supplying nutrients which may have been depleted or are lacking in the soil. Briefly explain how artificial nitrate fertilizers applied to farmer’s fields are creating “dead zones” along coastal oceans near river discharge areas. Be sure to include what causes the death of all those fish. (3 points)
10. Within an ecosystem there are a lot of important interactions between species. Individual organisms are identified as belonging to particular species. What is the scientific definition of a species? (1 point)
11. In general, each species has adapted to a unique role or ecological niche within an ecosystem. Some species have ecological niches that seem quite similar. In what way have 4 species of wood warblers (small, insect-eating birds) of the boreal forest adapted their behavior so that all 4 of the species can eat insects in the same type of fir tree at the same time of year? (2 points)
12. Within an ecosystem, food chains are energy flow systems.
a) What is the fundamental abiotic energy source that drives the entire system? (1 point)
b) Using the Rule of 10, briefly explain why a food chain is usually limited to just a few links. (2 points)
13. Using DDT to control insect populations as an example, briefly explain how the process of bioaccumulation works in ecosystems. (3 points) (More space available on next page)
14. Over long periods of time, species interacting within an ecosystem develop close interdependence. Occasionally, two species become so dependent upon each other that each directly affects the other’s evolution, a process called coevolution.
Hummingbird pollinated plants have evolved long, red, tubular flowers that provide a lot of nectar in order to attract hummingbirds. What do the plants gain by doing this that they would not otherwise have without it? (2 points)
15._____ Along the Pacific Coast of North America, mussels abound on the shoreline rocks of the intertidal zone. In that ecosystem, the sea star (starfish) is a keystone species because: (1 pt.)
Sea stars keep other species away
Sea stars eat all the mussels
Sea stars eat some of the mussels, which provide room for other species to live on the rocks along with the mussels.
The sea star is not a keystone species in that ecosystem
16. _____In New England, a region of northeastern U.S., abandoned farmland gradually returned to a type of forest with a species mix that was similar to the original forest of the area before conversion to farmland. The first tree species (pioneer species) to take over a field have certain characteristics that enable them to do that particularly well. Which of the following are likely characteristics of the first trees to grow in an abandoned field? (1 point)
a. wide ranging seed dispersal (often wind dispersed)
b. seedlings readily grow in the shade of other trees.
c. grow quickly to keep place in the sunshine.
d. only one generations in that location as conditions change from field to shady forest
e. all but b.
17. In 1859, Charles Darwin proposed a simple mechanism for species change over time, which is now a basic principle of biological science.
Major aspects of the mechanism are summarized in the phrase, “natural selection by means of survival of the fittest”:
a) What is meant by “natural selection” in this phrase? (1 point)
b) What did Mr. Darwin mean by the word “fitness”? (1 Point)
18.______ Shortly after the start of the Industrial Revolution, in the area around Manchester, England, industrial pollution killed the lichens that covered the tree trunks and soot settled on the bark causing the formerly light-colored tree trunks to become dark in color. After that, in the local population of peppered moths, dark-colored moths soon began to outnumber light-colored ones. What was the most likely explanation of what brought about this change in the wing color of the moths? (1 point)
a. Light-colored moths migrated to other locations
b. Insect-eating birds could easily see (and eat) light-colored moths against the now dark trunks.
c. Dark-colored moths were faster fliers and could dodge the birds easier
d. The increased warmth of the dark-colored trunks drove away the light colored moths.
19. Use only one of the following three examples, to briefly explain how adaptations to a particular ecological niche determine a species’ overall characteristics: (3 points).
Sloths, howler monkeys, spider monkeys
20. The Hawaiian Islands are volcanic islands that are located in the Pacific Ocean within the tropical zone about as far away from land as one can get. Explain the likely reasons why the Hawaiian Islands had a much lower total number of species than tropical mainland areas but had a much higher percentage of endemic species (species found nowhere else in the world).
(2 points)
21. Species X had a reduction in population until just a few individuals remained. Even even if conservation efforts can restore species X to its former abundance, what has been lost from the restored population that now restricts the capacity of this species to adapt to environmental change? (Assume that there are enough suitable, available habitats for successful population restoration.)
(2 points)
22. One of the main causes of species extinction today is the introduction into local ecosystems of species from other parts of the world. Use at least one specific example from the Bay Area to briefly explain how introduced species can lead to loss of biodiversity within an ecosystem. (2 points)
23. In general, there is greater species richness in the tropics than in mid-latitude or polar zones. ØList two major feeding niches that are available to tropical animal species throughout the year that are unavailable to animal species that remain active all winter in the boreal forest biome. (2 points)
24. Cacti are only found in the western hemisphere, but because of convergent evolution there are plants in the deserts of Africa and Australia which look similar to cacti. With regard to living under conditions of water scarcity, briefly explain the likely functional purposes of the following characteristic features of cacti (and other cactus-like desert plants). (2 points)
a. Green stems with no leaves
e. Stems covered by sharp spines.
25. ______Choose the letter that correctly indicates the order of the biomes found along the eastern side of North America from northern Florida (first) to northern Canada (last) (1 point)
1. deciduous broadleaf forest a. 1-2-3-4
2. evergreen needle-leaf forest (boreal) b. 4-2-1-3
3. tundra c. 4-3-2-1
4. evergreen needle-leaf forest (southern) d. 4-1-2-3
_______________________________________________________________________
BONUS QUESTIONS:
B-1. Since there have been other episodes of mass extinctions throughout the long history of this planet, why should we be concerned that humans are causing the 6th mass extinction? (2 points)
B-2. According to the excerpt from Annie Dillard’s book, Pilgrim at Tinker Creek:
Contrast nature’s stark facts of fecundity and death with the uniquely human perspective on the same phenomena. (2 points)
Explanation / Answer
1 . _____Living things are chemical systems. 99% of the molecular components of
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