Ecosystem Processes
Explain the role of decomposers in nutrient cycling.
Decomposers (such as fungi and bacteria) break down dead organic matter, converting it into simpler inorganic compounds that can be reused by producers. This process releases nutrients back into the soil, water, or air, maintaining nutrient cycles (like carbon, nitrogen, and phosphorus cycles) that are essential for ecosystem functioning.
Explain the concept of "carrying capacity" in relation to human populations.
Carrying capacity is the maximum population size that an environment can sustain indefinitely with available resources and without degradation. For humans, this depends on technology, resource management practices, consumption patterns, and waste management. Unlike other species, humans can temporarily exceed natural carrying capacity through technology, but this may lead to environmental degradation if not managed sustainably.
Compare and contrast renewable and non-renewable energy sources, providing two examples of each.
Renewable energy sources can be replenished naturally within a human lifespan and include solar and wind power. Non-renewable energy sources exist in finite quantities and include fossil fuels (oil, coal) and nuclear fuels. Renewables generally produce fewer emissions but may have intermittent availability, while non-renewables provide consistent energy but contribute to pollution and climate change.
Define "pollution" and explain the difference between point and non-point sources.
Pollution is the introduction of harmful substances or products into the environment. Point sources discharge pollutants at specific, identifiable locations (like factory pipes or smokestacks), making them easier to monitor and regulate. Non-point sources are diffuse, coming from many different places simultaneously (like agricultural runoff or urban stormwater), making them more difficult to control.
Define "biodiversity" and explain why its conservation is important.
Biodiversity refers to the variety of life forms within a given ecosystem, biome, or the entire Earth. Conservation is important because: biodiversity provides ecosystem services (clean air, water, pollination); offers resources for medicine, agriculture, and industry; increases ecosystem resilience to disturbances; has intrinsic and cultural value; and maintains genetic diversity essential for adaptation to environmental changes.
Describe the energy transfer efficiency between trophic levels in an ecosystem.
Energy transfer between trophic levels is typically only 10-20% efficient. This means that when one organism consumes another, only 10-20% of the energy from the consumed organism is incorporated into the consumer's biomass. The rest is lost as heat through metabolic processes or as waste.
Explain the concept of "ecological footprint" and its significance.
The ecological footprint measures human demand on nature by quantifying the area of biologically productive land and sea required to produce the resources we consume and absorb our waste. Its significance lies in highlighting whether our consumption patterns are sustainable or if we're exceeding Earth's regenerative capacity.
Describe the environmental impacts of fossil fuel extraction and combustion.
Environmental impacts include: air pollution (releasing particulates, sulfur dioxide, nitrogen oxides); greenhouse gas emissions contributing to climate change; habitat destruction from mining operations; water pollution from mining waste and oil spills; soil degradation; and health impacts on nearby communities such as respiratory problems and increased cancer risks.
Explain three ways in which air pollution affects human health.
Air pollution affects human health by: (1) Causing respiratory diseases like asthma, bronchitis, and emphysema due to particulate matter and ground-level ozone; (2) Increasing cardiovascular problems including heart attacks and strokes from fine particulates entering the bloodstream; and (3) Potentially causing developmental issues in children and contributing to certain cancers from long-term exposure to toxins like benzene and formaldehyde.
Compare and contrast in-situ and ex-situ conservation strategies.
In-situ conservation protects species within their natural habitats (e.g., protected areas, national parks), maintaining natural ecological processes and relationships. Ex-situ conservation preserves species outside their natural habitats (e.g., zoos, botanical gardens, seed banks). In-situ approaches preserve entire ecosystems but are vulnerable to habitat degradation, while ex-situ approaches provide insurance against extinction but cannot maintain all ecological relationships and evolutionary processes.
Explain the difference between a food chain and a food web.
A food chain is a linear sequence showing how energy passes from one organism to another as each consumes the previous organism. A food web is a more complex, interconnected network of multiple food chains within an ecosystem, showing all the possible feeding relationships at various trophic levels.
Identify three factors that contribute to increased resource consumption globally.
Three factors include: (1) Population growth - more people require more resources; (2) Rising affluence and consumption patterns - as people become wealthier, they tend to consume more resources; and (3) Technological development, which can both increase efficiency but also enable greater resource extraction and use.
Explain the concept of "energy efficiency" and provide three methods to improve it.
Energy efficiency refers to using less energy to perform the same task, reducing energy waste. Three methods to improve it include: (1) Improved building insulation to reduce heating/cooling needs; (2) Development of energy-efficient appliances and technologies; and (3) Implementation of smart grid technologies to optimize electricity distribution and use.
Describe the causes and effects of eutrophication in aquatic ecosystems.
Eutrophication is caused by excessive nutrients (particularly nitrogen and phosphorus) entering water bodies, typically from agricultural fertilizers, sewage, and detergents. Effects include: excessive algal growth; reduced water clarity; oxygen depletion as algae decompose; fish kills; changes in species composition; loss of biodiversity; and potential toxic algal blooms that can harm wildlife and humans.
Define "sustainable development" and explain its three pillars.
Sustainable development meets present needs without compromising future generations' ability to meet their own needs. The three pillars are: (1) Environmental sustainability - maintaining ecological integrity and natural resources; (2) Economic sustainability - promoting economic growth without environmental degradation; and (3) Social sustainability - ensuring equitable access to resources, health, education, and political participation for all people.
Define the term "ecosystem" and identify its main components.
An ecosystem is a biological community of interacting organisms and their physical environment. The main components include abiotic factors (non-living elements like climate, soil, water), biotic factors (living organisms like plants, animals, microorganisms), energy flows, and nutrient cycling.
Distinguish between exponential and logistic population growth.
Exponential growth occurs when a population increases at a constant rate over time, resulting in a J-shaped curve with no environmental constraints. Logistic growth occurs when environmental factors limit population size, resulting in an S-shaped curve as growth slows and eventually stabilizes at the carrying capacity.
hat are the advantages and limitations of nuclear power as an energy source?
Advantages include low greenhouse gas emissions during operation, high energy density, and reliable baseload power. Limitations include high construction costs, long-term radioactive waste management challenges, potential for catastrophic accidents, security concerns regarding nuclear material, and limited uranium resources.
Explain how biological indicators can be used to assess water quality.
Biological indicators are organisms whose presence, absence, or condition reflects environmental health. They can assess water quality by: examining species diversity (higher diversity often indicates better quality); monitoring indicator species that have known tolerance levels to pollution; assessing community structure changes; and observing physical abnormalities in organisms. Examples include macroinvertebrates like mayfly larvae (sensitive to pollution) and certain algae that proliferate in nutrient-rich conditions.
Explain the importance of Environmental Impact Assessments (EIAs) in development projects.
EIAs systematically identify, predict, and evaluate the environmental effects of proposed projects before implementation. Their importance lies in: identifying potential environmental issues early in planning; providing information for decision-making; suggesting mitigation measures; encouraging public participation; promoting sustainable development; complying with regulations; and potentially preventing costly environmental damage.
What is biomagnification and why is it an environmental concern?
Biomagnification is the process where certain substances (usually toxins or pollutants) increase in concentration as they move up the food chain. It's a concern because top predators can accumulate dangerous levels of these substances, which can lead to reproductive failure, behavioral abnormalities, diseases, and population declines in these species.
What is the demographic transition model, and what are its stages?
The demographic transition model describes how populations change over time in response to economic development. It has four main stages: Stage 1 (high birth rates, high death rates, stable population); Stage 2 (high birth rates, falling death rates, rapid population growth); Stage 3 (falling birth rates, low death rates, slowing population growth); Stage 4 (low birth rates, low death rates, stable or declining population). Some models include a fifth stage with birth rates below death rates.
Describe how hydroelectric power generation works and its potential environmental impacts.
Hydroelectric power generates electricity by using the energy of flowing water to turn turbines connected to generators. Environmental impacts include: alteration of river ecosystems; disruption of fish migration; changes in water quality and temperature; displacement of human communities; methane emissions from decomposing vegetation in reservoirs; and modification of downstream sediment transport affecting river delta ecosystems.
Describe the causes of acid rain and its environmental impacts.
Acid rain is caused primarily by emissions of sulfur dioxide and nitrogen oxides from burning fossil fuels, which react with water, oxygen, and oxidants in the atmosphere to form acidic compounds. Environmental impacts include: damage to aquatic ecosystems by lowering pH in water bodies; forest damage through soil acidification; reduced biodiversity; accelerated weathering of buildings and monuments; and leaching of toxic metals from soil into water supplies.
Describe three strategies for sustainable forest management.
Three sustainable forest management strategies include: (1) Selective logging - harvesting only certain trees while leaving the forest structure largely intact; (2) Certification programs (like FSC) - ensuring timber comes from responsibly managed forests through standards and auditing; and (3) Community forestry - involving local communities in forest management decisions, combining traditional knowledge with scientific approaches while providing economic benefits to residents.