BI 210 Chp 20 & 22
The area in a terrestrial ecosystem that is drained by a single stream; a common unit of study in terrestrial ecosystem studies; also called a watershed
catchment
A soil's ability to hold nutrient cations such as Ca2+, K+, and Mg2+ and exchange them with the soil solution, determined by the clay content of the soil.
cation exchange capacity
The chemical breakdown of soil minerals leading to the release of soluble forms of nutrients and other elements.
chemical weathering
The use of energy from inorganic chemical compounds to fix CO2 and produce carbohydrates using the Calvin cycle.
chemosynthesis
Fine soil particles
clay
All living plant tissues lose carbon via respiration, but not all living plant tissues acquire carbon via photosynthesis. Select one: True False
True
By means of a process called _______, some bacteria can use forms of _______ as electron donors to take up CO2 and convert it to carbohydrates. Select one: a. chemosynthesis; sulfur b. bacteriosynthesis; phosphate c. chemosynthesis; nitrogen d. bacteriosynthesis; potassium
a
Chemical energy derived from the fixation of carbon by photosynthesis and chemosynthesis is known as _______ production Select one: a. primary b. gross c. secondary d. net
a
How do plants and animals differ in how they take up nutrients? Select one: a. Plants take up simple chemicals, which they synthesize into larger molecules; animals take up larger, more complex molecules. b. Plants need to take in nitrogen-containing molecules, but animals do not. c. Plants take up complex molecules; animals take up relatively simple chemicals and synthesize larger molecules. d. Plants must absorb all 20 amino acids, whereas animals are able to synthesize all amino acids.
a
How does one estimate the NPP if one knows the NEE (net ecosystem exchange)? Select one: a. NPP = NEE - heterotrophic respiration b. NPP = NEE + autotrophic and heterotrophic respiration c. NPP = NEE + heterotrophic respiration d. NPP = NEE - atmospheric CO2
a
How does the nutrient cycle of aquatic systems differ from that of terrestrial systems? Select one: a. Inputs of nutrients from outside the ecosystems are more important in aquatic ecosystems. b. Nitrogen cycles are less important in aquatic ecosystems. c. Aquatic ecosystems are not dependent on decomposition. d. Chemical weathering does not contribute to nutrient supply in aquatic ecosystems.
a
In his experiments in lakes in Ontario, Canada, Schindler found evidence for phosphorus limitation of NPP. A massive increase in _______ was responsible for the increase of NPP in response to phosphorus addition. Select one: a. cyanobacteria b. red algae c. green algae d. brown algae
a
In some ecosystems, NPP actually decreases at very high levels of precipitation. Which of the following is not a likely reason for such declines in NPP? Select one: a. Respiration of heterotrophs increases at high precipitation levels. b. High precipitation levels can lead to the leaching of nutrients from the soil. c. High precipitation levels can lead to low oxygen levels in the soil. d. In areas where precipitation is extremely high, it is often cloudy, lowering available sunlight.
a
Silt is soil that Select one: a. has particles larger than clay. b. is very moist. c. has been leached. d. is derived from granite.
a
Suppose that heterotrophs ingested 1,660 kilograms of plant biomass over a month's period. Respiration of these heterotrophs was the equivalent of 790 kilograms, and they egested 520 kilograms. What is the net secondary production? Select one: a. 350 kilograms b. 870 kilograms c. 1140 kilograms d. 1,310 kilograms
a
What would be the mean residence time of phosphorus in a pond if the total pool is 1,250 grams and the mean rate of input is 2,500 grams? (Assume that rates of input, output, and the total pool size have remained constant.) Select one: a. 6 months b. 1 year c. 18 months d. 2 years
a
When studying terrestrial ecosystems, ecologists commonly focus on an area that is drained by a single stream, which is called a(n) Select one: a. catchment. b. occlusion. c. weir. d. ravine.
a
Which ecosystems have the slowest turnover rates of elements (the greatest mean residence times)? Select one: a. Boreal forests with large nutrient pools and low rates of litter input b. Temperate coniferous forests with low levels of nitrates in the soil c. Tropical forests with small nutrient pools and high rates of litter input d. Chaparrals with low amounts of moisture in the soil
a
Which statement about roots and root NPP is false? Select one: a. Root NPP is more difficult to estimate than aboveground NPP because roots turn over more slowly. b. The smallest roots are the most likely to turn over. c. Roots do not transfer carbon to symbionts. d. In order to accurately measure root NPP with harvest methods, roots must be harvested more frequently than aboveground biomass.
a
Why is there likely to be a higher diversity of plant species in soil derived from limestone than in soil derived from granite? Select one: a. The higher acidity of soil derived from granite lowers the availability of nitrogen and phosphorus to plants. b. Limestone attracts more bacteria and fungi, thereby increasing the nutrients in the soil. c. The higher acidity of soil derived from limestone increases the availability of nitrogen and phosphorus to plants. d. The lower acidity of soil derived from granite lowers the availability of nitrogen and phosphorus to plants.
a
Solid or liquid particles suspended in the atmosphere.
aerosols
The movement of particulate and dissolved matter from the atmosphere to Earth's surface by gravity or in precipitation
atmospheric deposition
A organism that converts energy from sunlight or from inorganic chemical compounds in the environment into chemical energy stored in the carbon-carbon bonds of organic compounds
autotroph
All other things being equal, herbivores generally must consume _______ food than carnivores in order to meet their nutritional needs. The reason is that plant material, per gram of carbon, contains _______ nitrogen than animal material does. Select one: a. more; more b. more; less c. less; more d. less; less
b
Earthworms contribute to decomposition by Select one: a. breaking down matter into inorganic nutrients through mineralization. b. breaking up litter into smaller particles, thereby increasing the surface area and allowing for more efficient chemical breakdown. c. decreasing the amount of oxygen in the soil, thereby increasing mineralization. d. releasing enzymes that convert inorganic molecules into organic macromolecules.
b
In which biome would you most likely see the greatest percentage of NPP devoted to roots? Select one: a. Pine savannas in Belize b. Tundra in Alaska c. Boreal forests in Russia d. Tropical forest in Panama
b
The availability of nutrient cations such as Ca2+, K+, and Mg2+ to plants may be insufficient in some soils that have low amounts of _______ particles. These particles have _______ that allow them to hold onto cations and exchange them with the soil solution. Select one: a. sand; strong positive charges b. clay; weak negative charges c. sand; semicrystalline structures d. clay; irregular structures
b
The total amount of photosynthesis is referred to as Select one: a. net primary production (NPP). b. gross primary production (GPP). c. net photosynthetic production (NPP). d. gross photosynthetic production (GPP).
b
The use of harvest techniques to estimate NPP would be most problematic in _______ because _______. Select one: a. temperate grasslands; the growth rate is very rapid b. temperate grasslands; tissues that die decompose rapidly c. tropical rainforests; tissues that die decompose rapidly d. temperate forests; the growth rate is very rapid
b
Which of the following is not an advantage of remote sensing technologies over harvesting estimates of NPP? Select one: a. They can provide more frequent estimates. b. They can provide more accurate estimates. c. They can be used over a greater area. d. They do not cause destruction of the area.
b
Which of the following is responsible for the most NPP produced within river and stream ecosystems? Select one: a. Phytoplankton suspended in the upper layers of the water b. Macrophytes in shallow areas c. Terrestrial plants d. The actions of detritivores
b
Which statement best describes the order of the nitrogen cycle? Select one: a. N2 is converted to proteins in plants; proteins are converted to NH4+ through decomposition; NH4+ is converted back to N2 through nitrogen fixation. b. Plant proteins are converted to N2 through decomposition; N2 is converted to NH4+ through nitrogen fixation; NH4+ is converted back to proteins in plants. c. N2 is converted to amino acids through nitrogen fixation; amino acids are converted to proteins in plants; proteins are converted to amino acids through decomposition; amino acids are converted back to proteins in plants. d. N2 is converted to NH4+ through nitrogen fixation; NH4+ is converted to proteins in plants; proteins are converted to NH4+ through decomposition; NH4+ is converted back to N2 via reverse nitrogen fixation.
b
The study of the physical, chemical, and biological factors that influence the movements and transformations of chemical elements.,
biogeochemistry
A crust on the soil surface composed of a mix of species of cyanobacteria, lichens, and mosses; also called a biocrust
biological soil crust
According to measurements taken in the 1990s, the levels of inorganic nitrogen in Arctic ecosystems were substantially lower than the amount of nitrogen actually taken up by plants. Which of the following is a possible explanation for this pattern? Select one: a. Arctic trees are able to perform nitrogen fixation with enzymes in their leaves. b. Microbes in the Arctic soil transform inorganic nitrogen into organic forms. c. Arctic sedges can take up organic forms of nitrogen. d. Arctic shrubs take up 60% of their nitrogen in the form of N2.
c
In experiments measuring the NPP of grassland ecosystems over time and at different sites, Lauenroth and Sala discovered that Select one: a. all grasslands respond to increased precipitation in the same way. b. the greatest response to increased precipitation occurred at one site over a period of time. c. some grasslands have different inherent abilities to increase growth in response to increased precipitation. d. Both a and b
c
Suppose that net secondary production in an ecosystem is only 15% of the total amount of plant material ingested by heterotrophs. If herbivores egest 20% of what they ingest, what percentage of what they ingest goes to heterotroph respiration? Select one: a. 20% b. 35% c. 65% d. 80%
c
Suppose two agents are introduced into soil: one that results in an increase in nitrification and another that results in an equal addition of denitrification. Compared to the soil before, the combination of equal amounts of nitrification and denitrification in the soil would result in a net increase in Select one: a. ammonium. b. nitrate. c. nitrous oxide. d. Both a and b
c
What did John Martin mean when he said "Give me half a tankerload of iron, and I'll give you an Ice Age"? Select one: a. Iron added to ocean water decreases NPP, and that decrease would lead to more carbon dioxide being taken up by phytoplankton. That would lead to the removal of carbon dioxide from the atmosphere, thus reducing the greenhouse effect. b. Iron added to ocean water increases NPP, and that increase would lead to less carbon dioxide being taken up by phytoplankton. With phytoplankton taking up less carbon dioxide, more carbon dioxide would be removed from the atmosphere, thus reducing the greenhouse effect. c. Iron added to ocean water increases NPP, and that increase would lead to more carbon dioxide being taken up by phytoplankton. That would lead to the removal of carbon dioxide from the atmosphere, thus reducing the greenhouse effect. d. Iron added to ocean water changes the specific heat of water, such that water can hold less heat. This leads to subsequent cooling of the atmosphere.
c
Which of the following is one example of the ways in which Arctic plant communities have avoided competition through resource partitioning? Select one: a. All Arctic species are able to use both inorganic and organic nitrogen. b. Arctic species lack chemicals that inhibit growth of other species. c. Different Arctic plant species take up nitrogen at different depths of the soil. d. Different Arctic plant species grow at different rates.
c
Which of the following would likely have the greatest proportion of productivity going into its own respiration? Select one: a. A short evergreen tree in New England b. A bunch of ferns in Canada c. A large tree in the Brazilian tropical rainforest d. A flower in the Brazilian tropical rainforest
c
Which statement best describes the relationship between mechanical and chemical weathering? Select one: a. Chemical weathering promotes mechanical weathering. b. Chemical weathering impedes mechanical weathering. c. Mechanical weathering promotes chemical weathering. d. Mechanical weathering impedes chemical weathering.
c
A large plant that grows in a warm, swampy environment and faces substantial herbivory most likely Select one: a. has a much larger than usual difference between its GPP and its NPP. b. allocates a relatively large proportion of its NPP to roots. c. allocates a relatively large proportion of its NPP to secondary compounds. d. Both a and c
d
According to measurements by Field and colleagues, the total NPP from terrestrial ecosystems is _______% of the total NPP. Select one: a. 10-20 b. 20-30 c. 30-40 d. 50-60
d
Heterotrophs are categorized by what they eat. A detritivore eats Select one: a. bacteria. b. fungi. c. algae. d. dead organic material.
d
Hilderbrand and colleagues wanted to determine the feeding ecology of the extinct European cave bear to determine whether individuals were herbivorous. To investigate this question, they Select one: a. examined the structure of cave bear teeth and jaws. b. measured the rare chemicals (such as ferosine) in the cave bears and compared them to the chemical composition of preserved remains of different food sources. c. measured the nitrogen isotopic composition of the cave bears and compared it to the isotopic composition of the different food sources. d. measured the ratio of carbon and nitrogen isotopes in cave bear bone samples and compared it to the ratios found in other known species whose diets were well known.
d
In the 1950s, anthropogenic eutrophication of Lake Washington was caused by Select one: a. nitrates from road runoff caused by severe rainstorms. b. introduced species of fish. c. high winds that caused increased turnover of benthic layers. d. phosphates from wastewater.
d
Of nitrogen and phosphorus, which is the most limiting nutrient to primary production early in primary succession, and why? Select one: a. Phosphorus, because it undergoes occlusion over time b. Nitrogen, because it undergoes chemical reactions with the phosphorus c. Nitrogen, because it takes a long time to accumulate in the soil through decomposition d. Phosphorus, because it is very soluble and is easily leeched from the soil
d
Plant species from resource-poor communities often have low growth responses to fertilization because these plants typically have a Select one: a. high tolerance for excess nutrients. b. low tolerance for excess nutrients. c. high intrinsic growth rate. d. low intrinsic growth rate.
d
Suppose that the net primary productivity of a particular ecosystem is 80 units per year. The respiration rate of primary producers is 30 units per year, and the respiration rate of herbivores is 10 units per year. The gross primary productivity is _______ units per year. Select one: a. 40 b. 50 c. 70 d. 110
d
Suppose that the net secondary production in a community is 530 kilograms. The respiration of heterotrophs is 1,400 kilograms, and the egestion is 350 kilograms. Plant respiration is 2,700 kilograms. How much plant material did the heterotrophs ingest? Select one: a. 530 kilograms b. 880 kilograms c. 1,930 kilograms d. 2,280 kilograms
d
When leaves change color during senescence, Select one: a. chlorophyll is broken down and the plant resorbs up to 60‒70% of the nitrogen in the leaves. b. chlorophyll is broken down and the plant resorbs 5‒10% of the nitrogen in the leaves. c. carbohydrates and starches are broken down and moved into stems and roots. d. Both a and c
d
Which statement about the soils on the Colorado Plateau is false? Select one: a. They are exposed to high levels of erosive forces. b. They are exposed to great climatic variation. c. The crusty nature of the soil is largely the work of filamentous cyanobacteria. d. Humans have had little impact on the soil conditions.
d
Which statement correctly describes the role of nitrogen fixation in the nutrient cycle? Select one: a. N2 is taken in by green plants and transformed into nitrogen-rich protein. b. N2 is inhaled by herbivores and transformed into ammonia, which can be dissolved in their blood. c. NH4+ is converted by certain bacteria into complex proteins that can then be ingested by animals. d. N2 is taken up by certain bacteria that can change it into ammonium, a form that is usable by plants.
d
The physical and chemical breakdown of detritus by detritivores, leading to the release of nutrients as simple, soluble organic and inorganic compounds that can be taken up by other organisms.
decomposition
A process by which certain bacteria convert nitrate (NO3-) into nitrogen gas (N2) and nitrous oxide (N2O) under hypoxic conditions
denitrification
All the abiotic and biotic components of a system that influence the flow of energy and elements
ecosystem
Nutrient-rich; characterized by high primary productivity.
eutrophic
A change in the nutrient status of an ecosystem from nutrient-poor to nutrient-rich; such changes occur naturally in some lakes due to the accumulation of sediments, but they may also be caused by nutrient inputs that result from human activities.
eutrophication
Energy in ecosystems originates with primary production by heterotrophs. Select one: True False
false
The nutrient requirements of organisms are pretty much all the same regardless of their physiological. As such, nutrient requirements of autotrophs and heterotrophs are very similar. Select one: True False
false
Variation in terrestrial NPP is associated with variation in the spatial distribution of fossil fuels around the world. Select one: True False
false
the amount of energy that autotrophs capture by photosynthesis and chemosynthesis per unit of time.
gross primary production (GPP)
The vertical movement of dissolved matter and fine mineral particles from upper to lower layers of soil
leaching
The area of leaves per unit of ground area (a dimensionless number, since it is an area divided by an area)
leaf area index
A structural compound that strengthens plant tissues.
lignin
Fresh, undecomposed organic matter on the soil surface
litter
The amount of time an average molecule of an element spends in a pool before leaving it.
mean residence time
The physical breakdown of rocks into progressively smaller particles without chemical change.
mechanical weathering
Having a nutrient status that is intermediate between oligotrophic and eutrophic, usually used in reference to lakes
mesotrophic
The chemical conversion of organic matter into inorganic compounds
mineralization
The combined fluxes of CO2 into and out of an ecosystem principally by net primary production and autotrophic and heterotrophic respiration
net ecosystem exchange (NEE)
The amount of energy per unit of time that producers capture by photosynthesis and chemosynthesis, minus the amount they use in cellular respiration
net primary production (NPP)
The balance between heterotroph energy gains through ingestion and heterotroph energy losses by cellular respiration and egestion
net secondary production
A process by which certain chemoautotrophic bacteria, known as nitrifying bacteria, convert ammonia (NH3) and ammonium (NH4+) into nitrate (NO3-) under aerobic conditions
nitrification
The process of taking up nitrogen gas (N2) and converting it into chemical forms that are more chemically available to organisms
nitrogen fixation
A chemical element required by an organism for its metabolism and growth.
nutrient
The cyclic movement of nutrients between organisms and the physical environment
nutrient cycle
A process by which soluble phosphorus combines with iron, calcium, and aluminum to form insoluble compounds (secondary minerals) that are unavailable to organisms as nutrients.
occlusion
Nutrient-poor, characterized by low primary productivity.
oligotrophic
A process that uses sunlight to provide the energy needed to take up CO2 and synthesize sugars.
photosynthesis
The total amount of a nutrient or other element found within a component of an ecosystem
pool
The rate at which chemical energy in an ecosystem is generated by autotrophs, derived from the fixation of carbon during photosynthesis and chemosynthesis
primary production
the coarsest soil particles (0.05-2 mm).
sand
Energy in an ecosystem that is derived from the consumption of organic compounds produced by other organisms.
secondary production
Intermediate-sized soil particles, often ranging in size between 0.05 and 0.002 mm
silt
A mix of mineral particles, detritus, dissolved organic matter, water containing dissolved minerals and gases (the soil solution), and organisms that develops in terrestrial ecosystems
soil
Layers of sediment deposited by glaciers.
till
Highest NPP is usually during intermediate stages of succession when plant diversity and nutrient supply tend to be highest. Select one: True False
true
Imports of nutrients from rivers and terrestrial ecosystems support production in marine ecosystems. Select one: True False
true
Root NPP is more difficult to estimate than aboveground NPP because roots turn over more quickly. Select one: True False
true
Specific nutrients play pivotal roles in the structure of ecosystems and the distribution and abundance of organisms. As such, the movement of some specific nutrients can structure communities. Select one: True False
true
The intrinsic growth rates of different plant species influences spatial variation in NPP and its response to variation in resource availability. Select one: True False
true
The physical and chemical processes by which rock minerals are broken down, eventually releasing soluble nutrients and other elements.
weathering
