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Phytoplankton are the autotrophic components of the plankton community, playing a crucial role in ocean and freshwater ecosystems.
Answer: True
Explanation: Phytoplankton are defined as the autotrophic components of the plankton community, essential for ocean and freshwater ecosystems.
The name 'phytoplankton' is derived from Ancient Greek words meaning 'animal' and 'swimmer'.
Answer: False
Explanation: The name 'phytoplankton' is derived from Ancient Greek words 'phutón' (plant) and 'planktós' (drifter, wanderer, roamer), translating to 'plant drifter'.
Phytoplankton obtain their energy through photosynthesis and must inhabit the well-lit surface layers of oceans and lakes.
Answer: True
Explanation: Phytoplankton are photoautotrophic organisms that rely on photosynthesis for energy, necessitating their presence in the euphotic zone of aquatic environments.
Compared to terrestrial plants, phytoplankton are distributed over a smaller surface area and have slower turnover rates.
Answer: False
Explanation: Phytoplankton are distributed over a significantly larger surface area and exhibit markedly faster turnover rates, measured in days, compared to terrestrial plants.
Most phytoplankton are microscopic, but when in very high concentrations, some varieties can form visible colored patches on the water surface.
Answer: True
Explanation: While individual phytoplankton are microscopic, their high concentrations can lead to visible colored patches on the water surface, a phenomenon often referred to as an algal bloom.
Phytoplankton are primarily composed of large, multicellular marine algae and sponges.
Answer: False
Explanation: Phytoplankton are a diverse group of photoautotrophic microorganisms, including photosynthesizing bacteria and unicellular protists, not large multicellular marine algae or sponges.
Mixoplankton are exclusively heterotrophic organisms that consume other organisms and do not photosynthesize.
Answer: False
Explanation: Mixoplankton are characterized by their ability to both photosynthesize (phototrophic) and ingest other organisms (heterotrophic), distinguishing them from purely heterotrophic organisms.
*Noctiluca* and *Dinophysis* are examples of obligate photoautotrophs that cannot ingest other organisms.
Answer: False
Explanation: *Noctiluca* and *Dinophysis* are examples of mixotrophic dinoflagellate genera, meaning they can photosynthesize and also ingest other organisms or detrital material.
The term 'phytoplankton' encompasses all photoautotrophic microorganisms in aquatic food webs, including protistan eukaryotes and both eubacterial and archaebacterial prokaryotes.
Answer: True
Explanation: The term 'phytoplankton' broadly includes all photoautotrophic microorganisms in aquatic food webs, such as protistan eukaryotes and both eubacterial and archaebacterial prokaryotes.
There are approximately 500 known species of marine phytoplankton, and the 'paradox of the plankton' refers to their rapid growth rates.
Answer: False
Explanation: There are approximately 5,000 known species of marine phytoplankton. The 'paradox of the plankton' refers to the ecological question of how such high diversity is maintained despite limited resources, not their rapid growth rates.
In oligotrophic oceanic regions, phytoplankton communities are dominated by small-sized cells like picoplankton and nanoplankton.
Answer: True
Explanation: Oligotrophic oceanic regions are indeed characterized by phytoplankton communities dominated by small-sized cells such as picoplankton and nanoplankton, including cyanobacteria and picoeukaryotes.
From which Ancient Greek words is the name 'phytoplankton' derived?
Answer: 'phutón' (plant) and 'planktós' (drifter)
Explanation: The name 'phytoplankton' is derived from the Ancient Greek words 'phutón' meaning 'plant' and 'planktós' meaning 'drifter, wanderer, roamer'.
Where do phytoplankton typically reside in aquatic environments to obtain energy?
Answer: In the well-lit surface layers, known as the euphotic zone
Explanation: Phytoplankton, being photosynthetic, must inhabit the well-lit surface layers of oceans and lakes, known as the euphotic zone, to access sunlight for energy production.
Which of the following statements accurately compares phytoplankton to terrestrial plants?
Answer: Phytoplankton are distributed over a significantly larger surface area and have faster turnover rates
Explanation: Compared to terrestrial plants, phytoplankton are distributed over a significantly larger surface area and exhibit markedly faster turnover rates, responding quickly to global climate variations.
How can phytoplankton, which are typically microscopic, sometimes be observed by the unaided eye?
Answer: They form visible colored patches on the water surface when in high concentrations
Explanation: While individual phytoplankton are microscopic, they can form visible colored patches on the water surface when present in very high concentrations, a phenomenon often associated with algal blooms.
Which of the following are primary types of organisms that comprise phytoplankton?
Answer: Photosynthesizing bacteria and unicellular protists like diatoms
Explanation: Phytoplankton comprise a diverse group of photoautotrophic microorganisms, including photosynthesizing bacteria (e.g., cyanobacteria) and various unicellular protists, such as diatoms.
What is the key distinction between phytoplankton and mixoplankton?
Answer: Phytoplankton are solely phototrophic, while mixoplankton are phototrophic and can ingest other organisms
Explanation: The key distinction is that while phytoplankton are traditionally considered solely phototrophic, mixoplankton are capable of both photosynthesis and ingesting other organisms, exhibiting a dual nutritional strategy.
Which of the following dinoflagellate genera are examples of mixotrophic species that can ingest other organisms or detrital material?
Answer: *Noctiluca* and *Dinophysis*
Explanation: Dinoflagellate genera such as *Noctiluca* and *Dinophysis* are recognized as mixotrophic species, capable of both photosynthesis and ingesting other organisms or detrital material.
In aquatic food webs, the term 'phytoplankton' includes which of the following types of microorganisms?
Answer: Protistan eukaryotes and both eubacterial and archaebacterial prokaryotes
Explanation: The term 'phytoplankton' broadly encompasses all photoautotrophic microorganisms in aquatic food webs, including protistan eukaryotes and both eubacterial and archaebacterial prokaryotes.
What is the 'paradox of the plankton' in marine ecology?
Answer: How such high diversity of phytoplankton is maintained despite scarce resources
Explanation: The 'paradox of the plankton' refers to the long-standing ecological question of how a high diversity of phytoplankton species can coexist and be maintained in an environment with seemingly limited resources, which would typically lead to competitive exclusion.
Which type of phytoplankton typically dominates in oligotrophic oceanic regions like the Sargasso Sea?
Answer: Small-sized cells like picoplankton and nanoplankton
Explanation: In oligotrophic oceanic regions, phytoplankton communities are typically dominated by small-sized cells such as picoplankton and nanoplankton, including *Prochlorococcus*, *Synechococcus*, and picoeukaryotes.
Phytoplankton are responsible for approximately half of the Earth's photosynthetic activity and at least half of the planet's oxygen production.
Answer: True
Explanation: Phytoplankton are indeed responsible for approximately half of the Earth's photosynthetic activity and at least half of the planet's oxygen production, making them crucial to global biogeochemical cycles.
Despite their significant global impact, phytoplankton constitute approximately 10% of the total global plant biomass.
Answer: False
Explanation: Phytoplankton constitute only approximately 1% of the total global plant biomass, despite their immense contribution to photosynthetic activity and oxygen production.
Phytoplankton contribute to primary production by creating organic compounds from carbon dioxide dissolved in the water through photosynthesis.
Answer: True
Explanation: Phytoplankton are primary producers, converting dissolved carbon dioxide into organic compounds through photosynthesis, thereby forming the base of aquatic food webs.
When phytoplankton cells die or are degraded, those not consumed or degraded slowly sink, ultimately fertilizing the seafloor.
Answer: True
Explanation: Phytoplankton biomass that is not consumed or degraded in the surface ocean slowly sinks, contributing organic matter and nutrients to the seafloor, a process integral to the biological pump.
A notable ocean food chain involves baleen whales directly consuming phytoplankton as their primary food source.
Answer: False
Explanation: In a significant ocean food chain, phytoplankton sustain krill, which then serve as the primary food source for baleen whales, indicating an indirect consumption by whales.
Coccolithophorids are notable for releasing significant amounts of dimethyl sulfide (DMS) into the atmosphere.
Answer: True
Explanation: Coccolithophorids are indeed notable for their significant role in releasing dimethyl sulfide (DMS) into the atmosphere, which has implications for climate regulation.
The CLAW hypothesis suggests a positive feedback loop where DMS released by coccolithophorids directly warms the atmosphere.
Answer: False
Explanation: The CLAW hypothesis proposes a negative feedback loop where DMS released by coccolithophorids contributes to cloud formation, which can increase cloud albedo and potentially lead to cooling, rather than directly warming the atmosphere.
Alfred C. Redfield proposed that zooplankton requirements control the ratio of carbon to nitrogen to phosphorus in the ocean.
Answer: False
Explanation: Alfred C. Redfield proposed that the elemental requirements of phytoplankton, not zooplankton, control the characteristic ratio of carbon to nitrogen to phosphorus observed in the ocean.
What percentage of the Earth's photosynthetic activity are phytoplankton responsible for?
Answer: Approximately half
Explanation: Phytoplankton are responsible for approximately half of the Earth's photosynthetic activity, playing a critical role in global carbon cycling.
What approximate percentage of the total global plant biomass do phytoplankton constitute?
Answer: 1%
Explanation: Despite their immense ecological impact, phytoplankton constitute only about 1% of the total global plant biomass.
How do phytoplankton contribute to primary production in aquatic environments?
Answer: By creating organic compounds from carbon dioxide through photosynthesis
Explanation: Phytoplankton are primary producers, converting dissolved carbon dioxide into organic compounds through photosynthesis, thereby forming the energetic foundation of aquatic food webs.
What is one fate of phytoplankton cells that are not consumed or degraded after they die?
Answer: They slowly sink, fertilizing the seafloor with their dead cells and detritus
Explanation: Phytoplankton cells that are not consumed or degraded after death slowly sink, contributing organic matter and nutrients to the seafloor, a process integral to the biological pump.
In a notable ocean food chain, what organism serves as the primary food source for baleen whales?
Answer: Krill
Explanation: In a key ocean food chain, phytoplankton support krill, which then serve as the primary food source for baleen whales, demonstrating an indirect trophic link.
Which phytoplankton group is particularly notable for releasing significant amounts of dimethyl sulfide (DMS) into the atmosphere?
Answer: Coccolithophorids
Explanation: Coccolithophorids are particularly notable among phytoplankton groups for their significant release of dimethyl sulfide (DMS) into the atmosphere, impacting atmospheric chemistry and climate.
According to the CLAW hypothesis, how do coccolithophorids contribute to a negative feedback loop linking marine biota and climate?
Answer: By releasing dimethyl sulfide (DMS) which can contribute to cloud formation
Explanation: The CLAW hypothesis posits that coccolithophorids contribute to a negative climate feedback loop by releasing dimethyl sulfide (DMS), which can oxidize to form sulfate aerosols that act as cloud condensation nuclei, potentially increasing cloud cover and albedo.
What significant finding did Alfred C. Redfield make regarding phytoplankton and ocean nutrient composition?
Answer: That phytoplankton's requirements control the ratio of carbon to nitrogen to phosphorus in the ocean
Explanation: Alfred C. Redfield's significant finding was that the elemental requirements of phytoplankton control the characteristic ratio of carbon, nitrogen, and phosphorus observed in the ocean, a principle known as the Redfield ratio.
What is the typical stoichiometric ratio for carbon, nitrogen, and phosphorus in the Redfield ratio?
Answer: 106:16:1
Explanation: The Redfield ratio describes the typical stoichiometric composition of phytoplankton and seawater as 106:16:1 for carbon, nitrogen, and phosphorus, respectively.
Phytoplankton can suffer from photodegradation if solar radiation is excessively high, and they adapt by possessing a wide array of photosynthetic pigments.
Answer: True
Explanation: Phytoplankton are susceptible to photodegradation from high solar radiation but adapt to varying light conditions by utilizing a diverse range of photosynthetic pigments.
The primary sources of nutrients for phytoplankton growth in the ocean are solely from atmospheric deposition.
Answer: False
Explanation: Primary nutrient sources for phytoplankton growth in the ocean include rivers, continental weathering, and glacial ice meltwater, in addition to atmospheric deposition.
Trace metals like iron, manganese, and zinc are essential micronutrients for phytoplankton growth.
Answer: True
Explanation: Trace metals such as iron, manganese, and zinc are indeed essential micronutrients for phytoplankton growth, and their limitation can influence community structure.
Beyond inorganic nutrients and trace metals, phytoplankton also depend on B vitamins for their survival.
Answer: True
Explanation: In addition to inorganic nutrients and trace metals, phytoplankton require B vitamins for their survival, with deficiencies in these vitamins correlating with lower populations in some oceanic areas.
Ocean acidification affects coccolithophore phytoplankton because their calcium carbonate shells are sensitive to changes in ocean pH.
Answer: True
Explanation: Coccolithophore phytoplankton are particularly vulnerable to ocean acidification due to their calcium carbonate shells (coccospheres), which are highly sensitive to decreases in ocean pH.
El Niño-Southern Oscillation (ENSO) cycles often lead to a substantial reduction in phytoplankton biomass and density in the Equatorial Pacific.
Answer: True
Explanation: El Niño-Southern Oscillation (ENSO) cycles, particularly El Niño phases, are known to cause significant reductions in phytoplankton biomass and density in the Equatorial Pacific due to altered biochemical and physical conditions.
How do different phytoplankton species adapt to variable underwater light conditions?
Answer: By possessing a wide array of photosynthetic pigments to absorb different wavelengths
Explanation: Phytoplankton adapt to variable underwater light conditions by possessing a diverse array of photosynthetic pigments, enabling them to efficiently absorb different wavelengths of light.
Which of the following is NOT listed as a primary source of nutrients for phytoplankton growth in the ocean?
Answer: Volcanic eruptions
Explanation: Primary sources of nutrients for phytoplankton growth include rivers, continental weathering, and glacial ice meltwater. Volcanic eruptions are not listed as a primary source in the provided information.
How is the availability of key macronutrients like nitrate, phosphate, and silicic acid regulated in the surface ocean for phytoplankton?
Answer: By the balance between the biological pump and upwelling of deep, nutrient-rich waters
Explanation: The availability of key macronutrients for phytoplankton in the surface ocean is regulated by the dynamic balance between the biological pump, which exports organic matter, and the upwelling of nutrient-rich deep waters.
Which of the following trace metals is listed as an essential micronutrient for phytoplankton growth?
Answer: Iron (Fe)
Explanation: Iron (Fe) is explicitly listed as an essential trace metal micronutrient for phytoplankton growth, with its limitation often impacting community structure.
Besides inorganic nutrients and trace metals, what other essential organic compounds do phytoplankton require for survival?
Answer: B vitamins
Explanation: Beyond inorganic nutrients and trace metals, phytoplankton also depend on B vitamins for their survival, with deficiencies in these compounds impacting populations in some oceanic areas.
Why are coccolithophore phytoplankton particularly sensitive to ocean acidification?
Answer: Their cells are covered by a calcium carbonate shell (coccosphere) sensitive to pH changes
Explanation: Coccolithophore phytoplankton are highly sensitive to ocean acidification because their protective calcium carbonate shells, or coccospheres, are vulnerable to dissolution and damage in lower pH conditions.
What is a common impact of El Niño-Southern Oscillation (ENSO) cycles on phytoplankton in the Equatorial Pacific?
Answer: A substantial reduction in phytoplankton biomass and density, especially during El Niño phases
Explanation: El Niño-Southern Oscillation (ENSO) cycles, particularly during El Niño events, typically lead to a substantial reduction in phytoplankton biomass and density in the Equatorial Pacific due to altered oceanographic conditions.
Anthropogenic warming is expected to decrease vertical stratification of the water column, leading to increased nutrient mixing and higher phytoplankton productivity.
Answer: False
Explanation: Anthropogenic warming is predicted to increase vertical stratification of the water column, which would reduce nutrient mixing from deeper waters to the surface, thereby decreasing phytoplankton productivity.
How is anthropogenic warming expected to significantly impact future phytoplankton productivity?
Answer: By changing vertical stratification, altering temperature-dependent reactions, and shifting atmospheric nutrient supply
Explanation: Anthropogenic warming is projected to significantly impact phytoplankton productivity by altering vertical stratification, changing temperature-dependent biological reaction rates, and shifting the atmospheric supply of essential nutrients.
A NASA visualization indicates that diatoms are large and require silica, while prochlorococcus are small and cannot use nitrate.
Answer: True
Explanation: According to a NASA visualization, diatoms are indeed large and require silica, while prochlorococcus are small and unable to utilize nitrate.
Iron fertilization is a universally accepted and implemented method for marine Carbon Dioxide Removal (mCDR).
Answer: False
Explanation: Iron fertilization remains a controversial topic within the ocean science community, with ongoing debates regarding its efficiency and potential ecosystem manipulation, and is not universally accepted or implemented as an mCDR method.
Phytoplankton are poor indicators of estuarine and coastal ecological health because they are highly resistant to environmental changes.
Answer: False
Explanation: Phytoplankton are highly sensitive to environmental changes, making them valuable and frequently used indicators of ecological health in estuarine and coastal areas.
According to a NASA visualization of global phytoplankton distribution, which type of phytoplankton is described as small and unable to use nitrate?
Answer: Prochlorococcus
Explanation: A NASA visualization identifies *Prochlorococcus* as a small type of phytoplankton that cannot utilize nitrate, playing a significant role in oligotrophic regions.
Why has iron fertilization been proposed as a method to combat atmospheric CO2 accumulation?
Answer: Phytoplankton in some ocean areas are iron-limited, and adding iron could promote CO2 uptake
Explanation: Iron fertilization has been proposed because phytoplankton in certain ocean regions are iron-limited, and supplementing iron could stimulate their growth, thereby enhancing CO2 uptake from the atmosphere.
Why are phytoplankton considered valuable indicators of estuarine and coastal ecological health?
Answer: They are highly sensitive to environmental changes
Explanation: Phytoplankton are considered valuable indicators of estuarine and coastal ecological health because their populations and community structures are highly sensitive and responsive to environmental changes.