Chapter 20 - ecosystem energetics Flashcards
) The heterotrophic component of the ecosystem is often subdivided into two subsystems: consumers and ________
decomposers
An ecosystem with inputs of matter and energy is a(n) ____ ecosystem
open
A(n) chemical reaction must absorb energy in order to proceed.
endothermic
The _____ law of thermodynamics states that when energy is transferred or transformed, part of the energy assumes a form that cannot pass on any further.
second
____ primary production is the total rate of photosynthesis or energy assimilated by plants.
Gross
The amount of accumulated organic matter found in an area at a given time is the ________ crop biomass.
standing
For photosynthesis and productivity to occur, a plant must open its ________ to take in carbondioxide
stomata
In a body of water, the depth at which the availability of light is such that the rate of photosynthesis equals the rate of respiration is called the ________ depth.
compensation
Organic carbon produced within an ecosystem is termed ________.
autochtonous
10) Relative net primary productivity is the ratio of net primary productivity to standing ________.
biomass
________ is the energy available to the heterotrophic component of the ecosystem
Net primary production
________ is the ratio of production to assimilation, which measures how efficiently the consumer incorporates assimilated energy into secondary
Production efficiency
Within any ecosystem, the two major food chains are the ________ food chain and the grazing food chain
detrital
) According to the first law of thermodynamics,
A) chemical reactions are exothermic.
B) entropy tends to increase.
C) potential energy tends to degrade into an unavailable form.
D) energy is neither created nor destroyed.
D) energy is neither created nor destroyed.
Plants assimilate energy through the process of A) decomposition. B) respiration. C) photosynthesis. D) regeneration.
C) photosynthesis.
An ecologist studying productivity in a sample of grasses measures gross primary productivityas 1000 kcal / m2 / yr and autotrophic respiration as 100 kcal / m2 / yr. Based on these calculations, the net primary productivity would be A) 10 kcal / m2 / yr. B) 900 kcal / m2 / yr. C) 1100 kcal / m2 / yr. D) 10,000 kcal / m2 / yr.
B) 900 kcal / m2 / yr.
Net primary productivity in an ecosystem increases as mean annual temperature
A) and mean annual rainfall decrease.
B) decreases and mean annual rainfall increases.
C) increases and mean annual rainfall decreases.
D) and mean annual rainfall increase
D) and mean annual rainfall increase
Net primary productivity is generally greatest at
A) tropical latitudes near the equator.
B) subtropical latitudes (e.g., 25° of latitude).
C) temperate latitudes (e.g., 50° of latitude).
D) polar latitudes (e.g., 80° of latitude)
A) tropical latitudes near the equator.
In the surface waters of oceans, the two most limiting nutrients for primary productivity are A) sulfur and phosphorus. B) sulfur and nitrogen. C) nitrogen and iron. D) nitrogen and phosphorus.
C) nitrogen and iron.
Low-moisture conditions favor allocation by a plant to A) leaves. B) stems. C) roots. D) flowers
C) roots.
Secondary production is limited primarily by A) water availability. B) nutrient availability. C) primary production. D) light availability
C) primary production.
Which organism is most likely to have the highest assimilation efficiency?
A) endothermic carnivore, such as a lion
B) ectothermic carnivore, such as a snake
C) endothermic herbivore, such as a deer
D) ectothermic herbivore, such as a grasshopper
A) endothermic carnivore, such as a lion
The base of the detrital food chain is formed by
a. primary producer
b. decomposer
c. herbivore
d. dead organic matter
d. dead organic matter
In most terrestrial and many aquatic systems, the ____ food chain is the dominant pathway of energy flow
a. detrital
b. grazing
c. consumer
d. heterotroph
a. detrital
Rates of herbivory are highest in
a. aquatic ecosystems dominated by phytoplankton
b. aquatic ecosystems dominated by vascular plants
c. terrestrial ecosystems dominated by herbaceous plants
d. terrestrial ecosystems dominated by woody plants
a. aquatic ecosystems dominated by phytoplankton
If herbivores eat 1000 kcal of plant energy, approximately how much energy will be converted into the tissues of herbivores?
a. 1 kcal
b. 10 kcal
c. 100 kcal
d. 1000 kcal
100 kcal
When a chemical reaction results in the loss of energy from the system, the reaction is exothermic.
True
The second law of thermodynamics is valid only valid in a closed system such as a living organism.
False
Productivity may be expressed in units of energy per unit area per unit time or in units of dry organic matter per unit area per unit time
True
Net primary productivity cannot be measured in aquatic ecosystems,
False
Net primary productivity is greater in areas with long photosynthetic period than in areas with short photosynthetic period
true
Net primary productivity is greater in temperate grasslands than in tropical rain forest
false
Net primary productivity is greater in open ocean than along the coast
false
In most marine ecosystem, autochthonous inputs of organic carbon are greater than allochthonous inputs of carbon.
True
In plants, low water availability favors the allocation of energy to the roots
true
In temperate rain forest, primary productivity remains relatively constant
false
Primary productivity in forests often increases during the early stages of stand development and then decreases again as the forest ages and standing biomass increases
true
Secondary production in an ecosystem is always less than primary production.
true
In endotherms, an increase in mass-specific metabolic rate lowers production efficiency.
True
Primary producers form the base of all food chains
false
In all food chains, the flow of energy is unidirectional from the bottom to the top.
False
Consumption efficiency is the ratio of ingestion to production
true
In terrestrial and shallow water ecosystems, the grazing food chain is dominant over the detrital food chain
false
In stream and river ecosystems, the grazing food chain is of minor importance compared with the detrital food chain
true
In most ecosystems, the biomass of carnivore is greater than the biomass of producers
false
In all ecosystems, the biomass of primary producers is greater than the biomass of herbivores
false
Brian Silliman:s research demonstrated that productivity in highly productive coastal salt marshes is controlled by bottom up forces such as physical condition and nutrient availability
false
Wealthy nations typically have lower rates of human appropriation of net primary productivity (HANPP) than developing nations.
false
