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bio test4

chapter 46

QuestionAnswer
Which of these is a heterotroph? a fish
They break down organic molecules into inorganic elements. They make their own organic molecules via photo- or chemosynthesis.
In food webs, chain lengths tend to be short.
. Trophic-level transfer efficiency averages about 10%.
The replacing forests with agricultural or urban areas can significantly affect the water cycle. Why is this? Less moisture is evapotranspired into the atmosphere after deforestation.
. A single oak tree can support hundreds of beetles, caterpillars and other primary consumers. This would be best represented by an inverted pyramid of numbers.
What is gross primary production? The carbon fixed during photosynthesis.
Ecosystem ecology is primarily concerned with movement of energy and materials through ecosystems.
The movement of chemicals through ecosystems is known as biogeochemical cycling
How does DDT in the environment affect many birds? decreased reproductive rate
Biogeochemical cycles involve the movement of chemicals through ecosystems.
In subarctic saltmarshes, scientists have found that the addition of calcium has no effect on productivity, but additional iron does increase productivity. In this example, iron is a limiting factor.
Lead is known to biomagnify and accumulates in the bones of organisms. What do you think is the fate of lead in the body of a tiger that has died of natural causes? Assume the tiger occupies the highest trophic level of its ecosystem. The lead will re-enter the food chain via decomposers breaking down the tiger's bone tissue.
Primary production is generally highest in wetlands.
. If gross primary production were to increase in an ecosystem, it would be reasonable to expect that the biomass of herbivores would increase.
What are the most important transformers of energy in ecosystems? plants and algae.
Which of these ecosystems has the lowest productivity? open ocean
Examine the map above (Figure 46.9), which shows indices of aquatic and terrestrial primary productivity based on concentrations of chlorophyll a. Based on this index, primary productivity of aquatic systems: tends to be high near polar regions.
The giant interconnected global ecosystem is called the biosphere.
The process by which elevated nutrient levels lead to an overgrowth of algae and the subsequent depletion of water oxygen levels is known as eutrophication.
Where are the largest reserves of carbon on the planet? rocks and fossil fuels
Stirling and Drake's conducted experiments about the effects of elevated atmospheric carbon dioxide on insect herbivory. What did they conclude about the effect of elevated CO2 on plant growth and herbivory? Higher plant growth, but reduced herbivore densities.
Each year, plants and algae remove approximately _______ of the CO2 in the atmosphere. 1/7th
What percentage of the earth's atmosphere consists of nitrogen (N2) gas? 78%
Ammonification is the conversion of ________ to NH3 and NH4. organic nitrogen
What do you think would result if aquatic species of nitrogen fixing cyanobacteria suffered dramatic population decreases? Algae populations would decline, but run off from industrial fixation would continue to provide enough nutrients to prevent their collapse.
The process by which soil bacteria convert NH3 or NH4 to nitrate (NO3-) is called nitrification.
Created by: Susyam