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23 Nov 2019

__________ is the amount of accumulated organic matter found inan area at a given time.

Question 20 options:

a) gross primary productivity

b) net primary productivity

c) standing crop biomass

d) regeneration load

e) net photosynthetic rate

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Related questions

The total amount of energy invested in the production of living biomass in a community is that community's

Select one:

a. gross primary productivity

b. net primary productivity

c. gross photosynthetic efficiency

d. net photosynthetic efficiency

Which of the following factors accounts for the largest number of documented extinctions that have occurred in the last 1,000 years?

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a. Deforestation

b. Habitat fragmentation

c. Pollution

d. Invasive species

In terrestrial ecosystems, the greatest current cause of species endangerment is

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a. invasive species

b. habitat loss

c. overharvesting

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Carbon dioxide has a warming effect on the earth's atmosphere. This is because it absorbs

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a. ultraviolet radiation coming from the earth's surface

b. visible light coming directly from the sun

c. ultaviolet radiation coming from the sun

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The overall productivity of the open ocean has declined as a result of global warming.This is believed to be because

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a. ocean stratification has intensified

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c. higher temperatures have directly inhibited algal photosynthesis

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Positive feedback might occur in response to increasing atmospheric carbon dioxide levels as a result of

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a. soil decomposers increasing the rate at which they break down organic molecules

b. oceans absorbing more carbon dioxide in the form of bicarbonate ions

c. an increase in the rate at which fossil fuels are formed

d. plants accelerating their growth by taking up more carbon dioxide

Which nitrogen-containing molecules in soil represent a usable source of nitrogen for plants?

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a. Nitrogenous bases of nucleic acids

b. All of these

c. Ammonium

d. Amino acids

In a tropical forest ecosystem, "edgeâ habitat is considered to be of relatively low quality for conservation purposes because it

Select one:

a. tends to contain more invasive species

b. all of these

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periwinklehorse209

1. You are an ecologist interested in energetics of ecologicalsystems. You begin your current research program with a study ofprimary productivity of corn plants growing in a field in Iowaduring mid-summer. At noon on a sunny day, you enclose a singleleaf (still attached to the plant) in a transparent chamber. Thechamber is connected to a measurement device called an infrared gasanalyzer, which is capable of measuring minute changes in theconcentration of carbon dioxide (CO2) of the atmosphere within thechamber. The chamber is also maintained at a constant 30Â°C (same asthe outside air temperature) during your observations. You firstexpose the corn leaf to full sunlight and observe that CO2 is beingdepleted by the leaf from the chamber at a rate of 18 mg CO2 per100 cm2 leaf area per hour. You then cover the chamber withaluminum foil to exclude all light and observe that CO2 is beingreleased by the leaf into the chamber at a rate of 3 mg CO2 per 100cm2 leaf area per hour.

Questions

What is the rate of net primary productivity for this leafduring the measurement period (In mg CO2 per 100 cm2 leaf area perhour)? What is the rate of respiration for this leaf (same units asabove)? What is the rate of gross primary productivityfor this leaf (same units as above)? At this site, cornis planted at a density that results in 75% of the surface beingcovered by leaves. What is the total net primary productivity forone hectare of this corn field (in g C per hectare per year)?Assume that day length averages 12 hours per day over the course ofa 180 day growing season and that your measurement isrepresentative of the NPP for the entire growing season. Show yourcalculations.

THIS IS PART A OF A QUESTION WITH ITS SUBPARTS

What approach could be used to determine if nitrogen availability in the soil directly limits the nutrient concentration of Metrosideros polymorpha leaves?

a)draining water from experimental plots where M. polymorpha is present

b) adding a known quantity of nitrogen to several experimental plots where M. polymorpha is present

c) removing leaf litter from a non-forested experimental plot and placing it into another where M. polymorpha is present

d) removing leaf litter from several experimental plots where M. polymorpha is present

e) Nutrient concentration in leaves cannot be accurately measured.

Decomposition would be highest in which of the following ecosystems?

a) temperate deciduous forest

b)desert

c) rain forest

d) coniferous (boreal) forest

e) arctic tundra

Which of the following is a result found by Dr. Schuur in this study?