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Primary production is exclusively carried out through photosynthesis, utilizing light energy to synthesize organic compounds from carbon dioxide.
Answer: False
Primary production occurs through both photosynthesis and chemosynthesis, the latter deriving energy from inorganic chemical compounds, not exclusively light.
Gross primary production (GPP) represents the total chemical energy created by primary producers, while net primary production (NPP) accounts for losses due to respiration and maintenance.
Answer: True
GPP is the total chemical energy produced, and NPP is GPP minus the energy lost through the primary producers' own respiration and maintenance.
The simplified chemical equation for chemosynthesis provided in the text shows the conversion of CO2, O2, and H2S into CH2O, S, and H2O.
Answer: True
The provided simplified equation for chemosynthesis is CO2 + O2 + 4 H2S → CH2O + 4 S + 3 H2O, which matches the statement.
The Calvin cycle is a series of biochemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose within the chloroplasts of photosynthetic organisms.
Answer: True
The Calvin cycle, a key component of photosynthesis, occurs in chloroplasts and involves the conversion of carbon dioxide and hydrogen-carrier compounds into glucose.
Primary producers are also known as heterotrophs because they consume organic matter from other organisms.
Answer: False
Primary producers are also known as autotrophs, as they synthesize their own organic compounds from inorganic carbon, unlike heterotrophs who consume organic matter.
The end products of primary production are primarily complex carbohydrates like cellulose, which are then directly respired for work.
Answer: False
The end products of primary production are polymers of reduced carbohydrates, such as glucose or other sugars, which are then used to synthesize more complex molecules or respired for work.
Net primary production (NPP) represents the rate at which all autotrophs within an ecosystem produce net useful chemical energy, available for growth, reproduction, and consumption by herbivores.
Answer: True
Net primary production (NPP) is precisely defined as the rate at which autotrophs produce net useful chemical energy, which supports their growth, reproduction, and higher trophic levels.
Almost all life on Earth depends directly or indirectly on primary production because it forms the base of the food chain.
Answer: True
Primary production is fundamental as it creates the organic compounds that form the base of the food chain, supporting nearly all life on Earth.
What is the fundamental process in ecology that refers to the biological synthesis of organic compounds using atmospheric or aqueous carbon dioxide?
Answer: Primary production
Primary production is defined as the biological synthesis of organic compounds from atmospheric or aqueous carbon dioxide.
Which of the following is NOT a primary mechanism by which primary production occurs?
Answer: Decomposition
Primary production occurs through photosynthesis (utilizing light energy) and chemosynthesis. Decomposition is a process of breaking down organic matter, not synthesizing it.
Why is primary production considered essential for almost all life on Earth?
Answer: It forms the base of the food chain by creating organic compounds.
Primary production is essential because it creates the organic compounds that form the base of the food chain, supporting all other trophic levels.
What are the organisms responsible for primary production called?
Answer: Primary producers or autotrophs
Organisms responsible for primary production are known as primary producers or autotrophs, as they synthesize their own organic matter.
Where do plants predominantly fulfill the role of primary producers?
Answer: In terrestrial ecoregions
Plants are the main primary producers in terrestrial ecoregions, while algae primarily fulfill this role in aquatic environments.
What is the relationship between Gross Primary Production (GPP) and Net Primary Production (NPP)?
Answer: NPP = GPP - respiration by plants
Net primary production (NPP) is calculated by subtracting the energy lost through respiration by primary producers from the gross primary production (GPP).
The Calvin cycle, a key part of photosynthesis, takes place in which cellular organelle?
Answer: Chloroplasts
The Calvin cycle, an integral part of photosynthesis, occurs within the chloroplasts of photosynthetic organisms.
What are the end products of primary production that are then used to synthesize more complex molecules or respired for work?
Answer: Polymers of reduced carbohydrates, such as glucose or other sugars
The end products of primary production are polymers of reduced carbohydrates, such as glucose or other sugars, which serve as building blocks and energy sources.
What does Net Primary Production (NPP) represent in an ecosystem?
Answer: The rate at which all autotrophs produce net useful chemical energy.
Net primary production (NPP) quantifies the rate at which autotrophs generate net useful chemical energy, available for their own processes and for consumption by other organisms.
What is the ecological distinction between 'production' and 'productivity'?
Answer: Production refers to the quantity of material produced, and productivity refers to the rate at which it is produced.
Ecologically, 'production' denotes the quantity of material produced, while 'productivity' refers to the rate at which that material is produced.
In terrestrial ecosystems, the most common unit for measuring gross and net primary production is grams of carbon per square meter per day (g C m^-2 day^-1).
Answer: False
The most common unit for measuring gross and net primary production in terrestrial ecosystems is grams of carbon per square meter per year (g C m^-2 yr^-1), not per day.
Historically, before the evolution of vascular plants, non-vascular plants likely played a more significant role in primary production on land.
Answer: True
The source states that before the evolution of vascular plants, non-vascular plants likely had a more significant role in terrestrial primary production.
Transpiration in plants accounts for approximately 50% of their water use and is primarily for cooling the plant.
Answer: False
Transpiration accounts for about 90% of a plant's water use and serves to transport water and nutrients, in addition to cooling.
CAM and C4 photosynthesis are adaptations that increase water-use efficiency, allowing for greater primary production in conditions that limit C3 plants.
Answer: True
CAM and C4 photosynthesis are physiological and anatomical adaptations that enhance water-use efficiency, enabling higher primary production under conditions that restrict C3 plants.
The animation of Earth's monthly terrestrial net primary productivity shows that tropical forests maintain high productivity year-round, with the Amazon basin peaking during its wet season.
Answer: False
The animation indicates that the Amazon basin's productivity peaks during its dry season, not its wet season, due to increased sunlight and groundwater access.
Primary production on land is primarily influenced by local hydrology and temperature, which correlates with photosynthetically active radiation (PAR).
Answer: True
Local hydrology (water availability) and temperature are the primary factors influencing terrestrial primary production, with temperature correlating with photosynthetically active radiation (PAR).
Stomata on plant leaves regulate gas exchange, where closing them to reduce water loss also increases carbon dioxide uptake.
Answer: False
When stomata close to reduce water loss, it also *decreases* carbon dioxide uptake, as they regulate the diffusion of both water vapor and CO2.
What is the most common unit of measurement for gross and net primary production in terrestrial ecosystems?
Answer: Grams of carbon per square meter per year (g C m^-2 yr^-1)
In terrestrial ecosystems, gross and net primary production are most commonly expressed in grams of carbon per square meter per year (g C m^-2 yr^-1).
Which organisms are primarily responsible for almost all terrestrial primary production today?
Answer: Vascular plants
Currently, vascular plants are responsible for almost all terrestrial primary production, with smaller contributions from other groups.
Which of the following is NOT a main factor influencing primary production on land?
Answer: Salinity
Primary production on land is primarily influenced by local hydrology, temperature, and photosynthetically active radiation (PAR). Salinity is a more significant limiting factor in aquatic environments.
What percentage of a plant's water use is accounted for by transpiration?
Answer: Approximately 90%
Transpiration accounts for about 90% of a plant's total water use.
How do stomata regulate gas exchange in plants?
Answer: They regulate the diffusion of water vapor out and carbon dioxide into the leaf.
Stomata regulate the diffusion of water vapor out of the leaf and carbon dioxide into the leaf, balancing water loss with CO2 uptake.
What is the primary benefit of Crassulacean acid metabolism (CAM) and C4 photosynthesis for certain plants?
Answer: They increase water-use efficiency, allowing greater primary production under limiting conditions.
CAM and C4 photosynthesis are adaptations that enhance water-use efficiency, enabling plants to achieve greater primary production in environments where C3 plants would be limited.
According to NASA's Terra satellite animation, what is a characteristic of tropical forests regarding productivity?
Answer: They maintain high productivity year-round, with variations like the Amazon basin peaking during its dry season.
The animation shows that tropical forests maintain high productivity throughout the year, with the Amazon basin specifically peaking during its dry season due to increased sunlight and groundwater access.
In oceanic ecosystems, the majority of primary production is performed by large autotrophs like seagrasses and macroalgae.
Answer: False
The majority of oceanic primary production is performed by free-living microscopic organisms known as phytoplankton, not large autotrophs.
The critical depth in oceanic primary production is the maximum depth of the mixed layer where net growth can occur, ensuring phytoplankton receive enough light.
Answer: True
The critical depth is defined as the maximum depth of the mixed layer where net growth can occur, which is essential for phytoplankton to receive sufficient light for net primary production.
In tropical ocean regions, primary production is highly seasonal, decreasing significantly in winter due to reduced light and increased mixing.
Answer: False
In tropical ocean regions, light varies only slightly, and mixing occurs episodically, meaning primary production is not highly seasonal in the same way as temperate regions.
Iron is considered a significant micronutrient in oceanic primary production because it acts as a cofactor in enzymes involved in processes like nitrate reduction and nitrogen fixation.
Answer: True
Iron is a crucial micronutrient in oceanic primary production, serving as a cofactor in enzymes essential for nitrate reduction and nitrogen fixation.
HNLC regions are characterized by high levels of chlorophyll and low nutrient availability, limiting phytoplankton growth.
Answer: False
HNLC (High-Nutrient, Low-Chlorophyll) regions are characterized by a scarcity of iron, which limits phytoplankton growth despite a surplus of other nutrients, leading to low chlorophyll levels.
In the oceans, light availability is crucial for primary production and is sufficient throughout the entire water column.
Answer: False
Light is crucial for oceanic primary production but is attenuated down the water column, meaning it is only sufficient in the photic zone, a thin layer near the surface.
Who are the main primary producers in the oceans?
Answer: Algae
In the oceans, algae are the main primary producers, performing almost all photosynthesis.
What type of organisms perform the majority of oceanic primary production?
Answer: Free-living microscopic organisms known as phytoplankton
The majority of oceanic primary production is carried out by free-living microscopic organisms called phytoplankton.
Which of the following is NOT a key limiting factor for primary production in the ocean?
Answer: Water availability
In the ocean, water availability is not a limiting factor for primary production, unlike light and mineral nutrients. Temperature fluctuations are also buffered by seawater.
What is the photic zone in the ocean?
Answer: A thin layer near the ocean's surface (10–100 m deep) where light is sufficient for photosynthesis.
The photic zone is the surface layer of the ocean, typically 10–100 meters deep, where sufficient light penetrates for photosynthesis to occur.
What condition must be met for net primary production to occur in the ocean's mixed layer?
Answer: The mixed layer must be shallower than the critical depth.
Net primary production occurs in the ocean when the mixed layer is shallower than the critical depth, ensuring phytoplankton receive adequate light for net growth.
In temperate ocean regions like the North Atlantic, how do seasonal cycles impact primary production?
Answer: Primary production decreases in winter due to reduced light and increased mixing.
In temperate ocean regions, primary production is highly seasonal, decreasing in winter due to lower light levels and increased mixing that disperses phytoplankton.
What is the primary source of replenishment for inorganic nutrients in the photic zone of the ocean?
Answer: Mixing or upwelling of deeper water.
Inorganic nutrients in the photic zone are primarily replenished by the mixing or upwelling of deeper, nutrient-rich water.
What is a major source of iron in the oceans?
Answer: Aeolian dust from Earth's deserts
A major source of iron in the oceans is aeolian dust, which originates from Earth's deserts and is transported by wind.
What characterizes HNLC (High-Nutrient, Low-Chlorophyll) regions in the ocean?
Answer: Scarcity of iron, leading to limited phytoplankton growth despite surplus other nutrients.
HNLC regions are characterized by a scarcity of iron, which limits phytoplankton growth and results in low chlorophyll levels despite the presence of other abundant nutrients.
Measuring gross primary production (GPP) is generally easier than measuring net primary production (NPP) due to the continuous nature of respiration.
Answer: False
Measuring gross primary production (GPP) is generally harder than measuring net primary production (NPP) because respiration is a continuous process that must be accounted for.
Field measurements for terrestrial NPP often overestimate the actual value because they typically account for below-ground productivity.
Answer: False
Field measurements for terrestrial NPP often *underestimate* the actual value because they *rarely* account for below-ground productivity and other factors.
Below-ground net primary production (BNPP) is frequently measured directly through excavation and weighing of root biomass.
Answer: False
Below-ground net primary production (BNPP) is difficult to measure directly and is often estimated based on a ratio of above-ground NPP (ANPP) to BNPP, rather than direct excavation.
The eddy covariance technique can be used to estimate Gross Primary Production (GPP) in terrestrial ecosystems by measuring Net Ecosystem Exchange (NEE) and scaling nighttime respiration to daytime values.
Answer: True
The eddy covariance technique measures NEE, and GPP is estimated by subtracting scaled daytime respiration from NEE, where nighttime respiration is used to scale.
In grasslands, peak standing biomass is a common method for measuring NPP, especially in systems dominated by annual plants.
Answer: True
Peak standing biomass is a frequently used method for measuring NPP in grasslands, particularly in systems dominated by annual plants.
The Gaarder and Gran technique for aquatic primary production involves incubating three vessels: one for initial oxygen, one for light, and one for darkness, to calculate gross production.
Answer: True
The Gaarder and Gran technique precisely involves incubating three vessels (initial, light, dark) to measure oxygen changes and calculate gross primary production.
The carbon-14 (14C) incorporation technique is widely used in ocean environments and is most accurate for estimating net primary production with short incubation times.
Answer: False
Short incubation times (1 hour or less) with the 14C incorporation technique are best for estimating *gross* primary production, while longer times reflect net primary production.
Methods based on stable isotopes and O2/Ar ratios require dark incubations to estimate respiration rates in aquatic systems.
Answer: False
Methods based on stable isotopes and O2/Ar ratios offer the advantage of providing estimates of respiration rates in the presence of light, eliminating the need for dark incubations.
When results are relevant to the carbon cycle, methods based on oxygen isotopes are generally preferred over carbon isotopes.
Answer: False
When results are specifically relevant to the carbon cycle, methods based on carbon isotopes are generally preferred over oxygen isotopes.
Forest productivity can be measured using biomass increment combined with litterfall, but this method is considered incomplete for above-ground net primary production (ANPP).
Answer: True
Biomass increment combined with litterfall is a method for measuring forest productivity, but it is considered an incomplete way to account for above-ground net primary production (ANPP).
What is a significant challenge in measuring terrestrial primary production?
Answer: A significant portion of productivity occurs below ground, which is hard to quantify.
A major challenge in measuring terrestrial primary production is that a substantial portion of productivity occurs below ground, making it difficult to quantify accurately.
For large-scale terrestrial areas, how is net primary production (NPP) typically estimated?
Answer: By tracking changes in dry-weight biomass over time.
For large terrestrial areas, net primary production (NPP) is commonly estimated by tracking changes in dry-weight biomass over time.
Which of the following is a limitation of field measurements for terrestrial NPP?
Answer: They rarely account for below-ground productivity.
A significant limitation of field measurements for terrestrial NPP is that they often fail to account for below-ground productivity, leading to underestimation.
How is Below-ground Net Primary Production (BNPP) typically estimated?
Answer: Based on a ratio of above-ground NPP (ANPP) to BNPP.
Due to the difficulty of direct measurement, below-ground net primary production (BNPP) is typically estimated using a ratio derived from above-ground NPP (ANPP).
The eddy covariance technique estimates Gross Primary Production (GPP) in terrestrial ecosystems by measuring Net Ecosystem Exchange (NEE) and then:
Answer: Subtracting scaled daytime respiration from NEE.
The eddy covariance technique estimates GPP by measuring NEE and then subtracting scaled daytime respiration, which is derived from nighttime respiration measurements.
What method is frequently used to measure NPP in grasslands, especially those dominated by annual plants?
Answer: Peak standing biomass.
Peak standing biomass is a common and effective method for measuring NPP in grasslands, particularly those dominated by annual plant species.
Which of the following is considered a suitable but incomplete way to account for above-ground net primary production (ANPP) in forests?
Answer: Biomass increment combined with litterfall.
Biomass increment combined with litterfall is considered a suitable, though incomplete, method for assessing above-ground net primary production (ANPP) in forest ecosystems.
Which of the following is NOT listed as one of the six main techniques for measuring primary production in aquatic systems?
Answer: Direct visual counting of phytoplankton cells.
Direct visual counting of phytoplankton cells is not listed among the six main techniques for measuring primary production in aquatic systems.
For the carbon-14 (14C) incorporation technique, what incubation time is best for estimating gross primary production?
Answer: 1 hour or less.
Short incubation times, specifically 1 hour or less, are optimal for estimating gross primary production using the carbon-14 (14C) incorporation technique.
What advantage do methods based on stable isotopes and O2/Ar ratios offer for measuring aquatic primary production?
Answer: They provide estimates of respiration rates in the presence of light, eliminating the need for dark incubations.
Methods utilizing stable isotopes and O2/Ar ratios offer the advantage of measuring respiration rates in the presence of light, thereby removing the necessity for dark incubations.
When results are specifically relevant to the carbon cycle, which methods are generally preferred?
Answer: Methods based on carbon isotopes.
For results directly relevant to the carbon cycle, methods based on carbon isotopes are generally preferred over oxygen isotopes.
The total global photoautotrophic primary production for Earth is estimated to be 104.9 petagrams of carbon per year, with terrestrial organisms accounting for slightly more than oceanic organisms.
Answer: True
Total global photoautotrophic primary production is estimated at 104.9 Pg C yr^-1, with terrestrial organisms contributing 56.4 Pg C yr^-1 (53.8%) and oceanic organisms 48.5 Pg C yr^-1 (46.2%).
Oceanic autotrophs represent a large percentage of Earth's total biomass, reflecting their significant contribution to global primary production.
Answer: False
Despite their significant contribution to primary production, oceanic autotrophs represent only about 0.2% of Earth's total biomass.
Historical estimates of primary productivity rely on direct measurements from ancient ecosystems, similar to present-day methods.
Answer: False
Historical estimates of primary productivity rely on biogeochemical models and geochemical proxies, not direct measurements from ancient ecosystems.
The Great Oxidation Event and the Neoproterozoic era are associated with notable decreases in Earth's primary production.
Answer: False
Historical records indicate that the Great Oxidation Event and the Neoproterozoic era are associated with notable *increases* in Earth's primary production.
What is the estimated total global photoautotrophic primary production for Earth?
Answer: 104.9 Pg C yr^-1
The total global photoautotrophic primary production for Earth is estimated to be 104.9 petagrams of carbon per year (Pg C yr^-1).
How is global primary production divided between terrestrial and oceanic organisms?
Answer: Terrestrial organisms account for 53.8%, oceanic for the remaining 46.2%.
Terrestrial organisms contribute 56.4 Pg C yr^-1 (53.8%) to global primary production, while oceanic organisms contribute 48.5 Pg C yr^-1 (46.2%).
What is a significant difference in biomass between terrestrial and oceanic autotrophs?
Answer: Oceanic autotrophs represent only about 0.2% of Earth's total biomass.
Despite their substantial contribution to global primary production, oceanic autotrophs constitute only about 0.2% of Earth's total biomass.
What do historical estimates of primary productivity primarily rely on?
Answer: Biogeochemical models and geochemical proxies.
Historical estimates of primary productivity are primarily derived from biogeochemical models and geochemical proxies, rather than direct measurements.
Which geological events are associated with notable increases in primary production throughout Earth's past?
Answer: The Great Oxidation Event and the Neoproterozoic era.
Notable increases in Earth's primary production are associated with significant geological events such as the Great Oxidation Event and the Neoproterozoic era.
Human Appropriation of Net Primary Production (HANPP) is an indicator designed to quantify the human impact on nature by estimating the portion of NPP that human societies use or alter.
Answer: True
HANPP is an indicator developed to quantify human impact on ecosystems by measuring the portion of NPP that human societies utilize or modify.
Irrigation in regions like the Nile valley has globally led to a significant reduction in actual NPP (NPPact) due to land use changes.
Answer: False
While human land use generally leads to NPP reduction, irrigation in some regions, such as the Nile valley, has actually *increased* primary production.
In 2000, approximately 34% of Earth's ice-free land area was dedicated to human agriculture, impacting biodiversity and ecosystem services.
Answer: True
In 2000, an estimated 34% of Earth's ice-free land area was used for human agriculture, leading to significant impacts on biodiversity and ecosystem services.
Earth System Models project an increase in ocean net primary production (NPP) due to climate change, benefiting marine ecosystems.
Answer: False
Earth System Models suggest that climate change could lead to *reductions* in ocean net primary production (NPP), negatively impacting marine ecosystems.
The total Human Appropriation of Net Primary Production (HANPP) considering end consumption by people is estimated to be 9.6% of the potential vegetation's net primary production (NPP0).
Answer: False
When considering end consumption by people, the total Human Appropriation of Net Primary Production (HANPP) is estimated to be 23.8% of the potential vegetation's net primary production (NPP0).
Who designed the Human Appropriation of Net Primary Production (HANPP) indicator?
Answer: Josep Garí
The Human Appropriation of Net Primary Production (HANPP) indicator was designed by Josep Garí in 1996.
What is the estimated global reduction in NPP due to human land use changes (ΔNPP_LC)?
Answer: 9.6%
The global reduction in NPP due to human land use changes (ΔNPP_LC) is estimated at 9.6% across global landmass.
What percentage of the potential vegetation's net primary production (NPP0) is appropriated by humans when considering end consumption?
Answer: 23.8%
When accounting for end consumption by people, the total Human Appropriation of Net Primary Production (HANPP) reaches 23.8% of the potential vegetation's net primary production (NPP0).
In 2000, what percentage of Earth's ice-free land area was dedicated to human agriculture?
Answer: 34%
In 2000, human agriculture utilized an estimated 34% of Earth's ice-free land area (12% cropland and 22% pasture).
What do Earth System Models suggest about the impact of climate change on ocean net primary production (NPP)?
Answer: Reductions in NPP ranging between 3% and 10% of current values.
Earth System Models project that climate change will lead to reductions in ocean net primary production (NPP) ranging from 3% to 10% of current values.