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Questions and Answers
Which of the following species is classified as having a 'Least Concern' extinction risk?
Which of the following species is classified as having a 'Least Concern' extinction risk?
Autotrophs, such as green plants, can produce their own food through photosynthesis.
Autotrophs, such as green plants, can produce their own food through photosynthesis.
True
What is the formula to calculate Net Primary Production (NPP)?
What is the formula to calculate Net Primary Production (NPP)?
NPP = GPP - R
The _____ productivity shows a general increase near the equator due to higher temperatures and rainfall.
The _____ productivity shows a general increase near the equator due to higher temperatures and rainfall.
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Match the following terms related to ecosystem productivity:
Match the following terms related to ecosystem productivity:
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Which ecosystem has the highest mean net primary productivity (NPP)?
Which ecosystem has the highest mean net primary productivity (NPP)?
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Deserts have a higher mean NPP compared to tundra and alpine ecosystems.
Deserts have a higher mean NPP compared to tundra and alpine ecosystems.
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What is the total area of the open ocean in million square kilometers?
What is the total area of the open ocean in million square kilometers?
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In a food chain, the transfer of energy typically starts with _________.
In a food chain, the transfer of energy typically starts with _________.
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Match the ecosystem with its corresponding mean NPP:
Match the ecosystem with its corresponding mean NPP:
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Which ecosystem contributes the least to the total marine NPP?
Which ecosystem contributes the least to the total marine NPP?
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A food web consists of multiple interconnected food chains.
A food web consists of multiple interconnected food chains.
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What is the mean NPP of cultivated land in tkm-2?
What is the mean NPP of cultivated land in tkm-2?
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Which level of biological diversity was recognized as a fourth level in 2003?
Which level of biological diversity was recognized as a fourth level in 2003?
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Deserts are rich in species diversity due to their favorable climate.
Deserts are rich in species diversity due to their favorable climate.
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What biome is characterized by widely spaced trees and a mixture of woodland and grassland?
What biome is characterized by widely spaced trees and a mixture of woodland and grassland?
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The biome that covers nearly 30% of the world's forests is known as the ______.
The biome that covers nearly 30% of the world's forests is known as the ______.
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Which factor is considered the most important in determining the suitability of a habitat for organisms?
Which factor is considered the most important in determining the suitability of a habitat for organisms?
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Match the following biomes with their characteristics:
Match the following biomes with their characteristics:
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Oceans cover 50% of the Earth's surface and support nearly half of all species.
Oceans cover 50% of the Earth's surface and support nearly half of all species.
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What is the primary reason boreal forests are important in the context of carbon storage?
What is the primary reason boreal forests are important in the context of carbon storage?
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Study Notes
Autotrophs & Heterotrophs
- Producers, including green plants, algae, and certain bacteria, play a foundational role in ecosystems by capturing solar energy and converting it into chemical energy in the form of sugars through a process known as photosynthesis. This process is essential as it provides the organic compounds necessary for the survival of almost all living organisms.
- Consumers, in contrast, are referred to as heterotrophs because they lack the capability to create their own food through photosynthesis or chemosynthesis. Instead, they depend on other organisms, whether plants or animals, to obtain their energy and nutrients, thereby playing a vital role in energy transfer within ecosystems.
Photosynthesis
- The fundamental chemical equation that describes photosynthesis is: 6CO2 + 6H2O -> C6H12O6 + 6O2. In this equation, carbon dioxide and water are converted, with the aid of sunlight, into glucose (a simple sugar) and oxygen. This process not only produces energy-rich compounds but also releases oxygen, which is critical for the survival of aerobic organisms.
Primary Productivity (PP)
- Primary Productivity (PP) refers to the rate at which biomass, meaning the total mass of living organisms in a given area, is produced by primary producers like plants and algae. This metric is typically expressed per unit area, allowing comparison across different habitats.
- Gross Primary Productivity (GPP) measures the total amount of energy captured through photosynthesis without accounting for the energy used by the plants themselves in cellular respiration. It reflects the overall energy availability in an ecosystem.
- Respiration (R), in ecological terms, is the energy that is lost as heat during the metabolic processes in organisms. This loss of energy is significant because it influences the amount of energy that remains available for growth and reproduction.
- Net Primary Production (NPP) is calculated by subtracting the energy lost through respiration (R) from the gross primary productivity (GPP): NPP = GPP - R. This yields the rate of new biomass that is available for consumption by heterotrophs, ultimately supporting the entire food web.
NPP Trends
- NPP exhibits considerable variation across the globe, with regions near the equator typically demonstrating higher NPP values due to more favorable climatic conditions, abundant sunlight, and longer growing seasons. Conversely, arid regions such as deserts and vast expanses of open oceans tend to have significantly lower NPP due to limiting factors like inadequate moisture and nutrient availability.
- Open oceans, often referred to as marine deserts, exemplify areas with low NPP. Despite covering a major portion of the Earth's surface and playing a critical role in global oxygen production, these areas often lack the nutrients necessary for supporting extensive primary productivity.
- In certain regions, whether temperate or tropical, upwellings of nutrient-rich water from the ocean floor can drastically enhance productivity. These upwellings promote biological activity and lead to higher NPP, even in otherwise cold or nutrient-poor areas, thus illustrating the dynamic and variable nature of marine ecosystems.
Ecosystem NPP (Table Summary)
- The ecosystems exhibiting the highest NPP are Tropical Rainforests, which boast an astonishing annual production of approximately 37.4 x 109 tonnes/yr. The high temperatures, frequent rainfall, and biodiversity contribute to this productivity.
- In stark contrast, Deserts and regions dominated by Rock/Ice are characterized by minimal primary productivity, with NPP values of 1.6 x 109 tonnes/yr and 0.07 x 109 tonnes/yr, respectively. These environments have extreme temperature fluctuations and limited water availability, resulting in sparse vegetation and low overall biological productivity.
- Marine ecosystems, through their vastness and diversity, contribute significantly to global primary productivity, estimated at about 55 x 109 tonnes/yr. The interplay of sunlight, nutrient availability, and biological interactions in these ecosystems makes them crucial for overall ecological balance.
Food Chains & Food Webs
- Food chains are linear representations of energy transfer within an ecosystem, illustrating how energy moves from primary producers to primary consumers and onward to secondary consumers and tertiary consumers. Each step in this chain is a trophic level, which defines the position of an organism within this hierarchy.
- Food webs provide a more complex depiction of these interactions by illustrating how various food chains intertwine and overlap in a given ecosystem. This interconnectedness reflects the diverse dietary habits of species and emphasizes the stability provided by biodiversity, allowing ecosystems to withstand changes over time due to external factors such as climate change, habitat alteration, and human activities.
Biodiversity
- Traditional levels of biodiversity encompass species diversity (the variety of different species within a particular habitat), ecosystem diversity (the range of different ecosystems within a particular area), and genetic diversity (the variation of genes within a species). Collectively, these factors reflect the health and stability of natural environments.
- A fourth level termed molecular diversity was introduced to better encompass the genetic variations that can occur at a molecular level within species, which can have significant implications for evolutionary processes and adaptive capacities of organisms. This inclusion brings a more comprehensive understanding of biodiversity, acknowledging even the microscopic facets of life.
Distribution of Organisms
- Organisms display distinctive patterns of distribution across the globe, which often correlate with specific habitat characteristics, including availability of resources, climate, and ecological interactions. These distributions directly influence biodiversity and the functional dynamics of ecosystems.
- Climate is a principal factor that dictates habitat suitability for organisms, significantly influencing variables such as temperature, humidity, and precipitation. Consequently, different organisms have evolved unique adaptations to thrive in concordance with their specific environmental conditions.
- For instance, Tropical rainforests are highly regarded for their exceptional biodiversity, thriving in regions with optimal temperature and moisture conditions. The dense canopy and complex layering create a plethora of niches for various species.
- On the other hand, Deserts typically exhibit low biodiversity, primarily due to the constraints posed by extreme temperatures and limited water resources, which challenge the survival of many species.
- The ocean is a vast biome that covers approximately 71% of the Earth's surface, serving as a home to nearly half of all known species. Its myriad habitats, from coral reefs to deep sea trenches, exhibit a range of biodiversity levels, influenced by factors such as depth, light availability, and nutrient concentration.
Biomes
- Biomes are large ecological areas characterized by distinct climate patterns and certain types of vegetation and wildlife adapted to those conditions. Each biome supports specific plant and animal life, demonstrating the intricate interplay between climate and biological diversity.
- Examples of biomes encompass a variety of environments including tropical rainforests, savannas, deserts, tundras, and taiga, each supporting unique ecosystems and communities of organisms.
- Tropical rainforests, often regarded as the most complex biome, feature a multi-layered canopy structure that houses an extraordinarily high diversity of flora and fauna, making them vital for global biodiversity.
- Savannas are characterized by a mix of trees and grasses, offering open spaces that support a distinct variety of herbivores and carnivores. These mixed woodland grasslands are shaped by seasonal rainfall patterns, which dictate the growth and sustainability of vegetation.
- Deserts present harsh living conditions defined by exceptionally low precipitation and extreme temperature fluctuations. Vegetation here includes specially adapted plants like cacti and succulents that can conserve water, illustrating the resilience of life even in the most challenging environments.
- Tundra environments are typically treeless and lie in polar regions, featuring a simple structure with limited species diversity. These ecosystems are defined by permafrost, which affects plant growth and fauna survival, resulting in unique adaptations for harsh climatic conditions.
- Taiga, or boreal forest, is characterized by its dominance of coniferous trees, forming a continuous belt across North America and Eurasia. This biome plays a critical role in carbon storage, significantly contributing to global efforts in mitigating climate change, as boreal forests make up about 30% of the planet’s forested area.
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Description
Test your knowledge on autotrophs and heterotrophs, their roles in ecosystems, and the processes of photosynthesis and primary productivity. This quiz covers key terms, equations, and trends related to NPP and how it varies globally.
