APES Unit 1 study guide

Abiotic

Abiotic

Non-living components of an ecosystem, such as sunlight, water, temperature, and minerals, that influence living organisms.

Autotrophs (producers)

Organisms that produce their own food using sunlight (photosynthesis) or chemical energy (chemosynthesis), forming the base of the food chain.

Biosphere

The global sum of all ecosystems, where life exists, encompassing land, water, and the atmosphere.

Biotic

Living components of an ecosystem, including plants, animals, fungi, and microorganisms, that interact with each other and their environment.

Carnivores

Animals that primarily eat other animals, playing a key role in controlling prey populations and maintaining ecological balance.

Cellular respiration

The process by which cells convert glucose and oxygen into energy (ATP), producing carbon dioxide and water as byproducts.

Chemosynthesis

The process by which certain organisms, like bacteria, convert inorganic compounds (e.g., hydrogen sulfide) into organic matter using chemical energy, often in environments without sunlight.

Community

A group of different species living together in a particular area, interacting with each other and their environment.

Decomposers

Organisms, such as bacteria and fungi, that break down dead organic matter, recycling nutrients back into the ecosystem.

Detrivores

Organisms that feed on dead organic matter and organic waste, helping to break it down and recycle nutrients within ecosystems.

Acid rain (deposition)

Precipitation with a lower pH due to pollutants, primarily sulfur dioxide and nitrogen oxides, which can harm ecosystems, soil, and water bodies.

Aquifer

A geological formation that can store and transmit water, typically made up of permeable rock or sediment, providing groundwater for wells and springs.

Ammonification

The process by which decomposers convert organic nitrogen (from dead organisms and waste) into ammonia, making it available for further processing in the nitrogen cycle.

Assimilation

The process by which plants and animals incorporate nutrients (like nitrogen and phosphorus) from their environment into their own cells and tissues.

Biogeochemical cycles

Natural processes that recycle nutrients in different forms from the environment to living organisms and back, including cycles like the carbon, nitrogen, and water cycles.

Carbon cycle

The series of processes by which carbon is exchanged among the atmosphere, land, oceans, and living organisms, including processes like photosynthesis, respiration, and combustion.

Cellular respiration

(Already defined earlier) The process by which cells convert glucose and oxygen into energy (ATP), producing carbon dioxide and water as byproducts.

Combustion

A chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light, and producing carbon dioxide and water as byproducts.

Condensation

The process by which water vapor in the atmosphere cools and changes into liquid water, forming clouds and precipitation.

Ecological pyramids

Diagrams that represent the distribution of energy, biomass, or the number of organisms in an ecosystem at different trophic levels, typically structured as pyramids with producers at the base and top predators at the apex.

Ecosystem

A community of living organisms interacting with their physical environment, including both biotic (living) and abiotic (non-living) components, functioning together as a system.

Energy flow

The movement of energy through an ecosystem, typically starting from sunlight, which is captured by producers through photosynthesis and then transferred to consumers through food chains and webs.

Food web

A complex network of interconnected food chains within an ecosystem, illustrating how energy and nutrients flow among various organisms, highlighting the multiple feeding relationships.

Gross primary productivity (GPP)

The total amount of energy captured by photosynthetic organisms (producers) in an ecosystem during a given time period, before accounting for the energy used in respiration.

Herbivores

Organisms that primarily consume plants or plant-based materials, serving as primary consumers in food chains and webs and playing a vital role in energy transfer.

Heterotrophs (consumers)

Organisms that cannot produce their own food and rely on consuming other organisms (plants or animals) for energy. This group includes herbivores, carnivores, and omnivores.

Net primary productivity (NPP)

The amount of energy that remains after producers have used some energy for their own respiration; it represents the energy available for consumers in the ecosystem.

Phytoplankton

Microscopic, photosynthetic organisms found in aquatic environments, serving as primary producers in marine and freshwater ecosystems and forming the base of the food web in these habitats.

Photosynthesis

The process by which green plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose and oxygen, providing energy for the organism and oxygen for the atmosphere.

Decomposition

The process by which dead organic matter is broken down by decomposers (such as bacteria and fungi), recycling nutrients back into the ecosystem and enriching the soil.

Denitrification

The process by which bacteria convert nitrates in the soil back into nitrogen gas (N₂), returning nitrogen to the atmosphere and completing the nitrogen cycle.

Eutrophication

The process by which excessive nutrients (often from fertilizers) enter water bodies, leading to algal blooms, oxygen depletion, and harm to aquatic life as the decomposition of algae consumes oxygen.

Evaporation

The process by which water changes from a liquid to a gas (water vapor) due to heat, playing a crucial role in the water cycle and contributing to cloud formation.

Fossil fuels

Natural fuels, such as coal, oil, and natural gas, formed from the remains of ancient plants and animals over millions of years, serving as major energy sources but also contributing to carbon emissions.

Groundwater

Water that fills the spaces and cracks in underground soil and rock formations, serving as a vital source of freshwater for drinking, irrigation, and ecosystems.

Hydrologic cycle

The continuous movement of water through the environment, involving processes such as evaporation, condensation, precipitation, infiltration, and runoff, maintaining the distribution of water on Earth.

Infiltration

The process by which water on the ground surface enters the soil, replenishing groundwater supplies and affecting water availability for plants and ecosystems.

Nitrogen cycle

The series of processes by which nitrogen is converted between its various chemical forms in the environment, including nitrogen fixation (conversion of atmospheric nitrogen into usable forms), ammonification, nitrification (conversion of ammonia into nitrates), assimilation by plants, and denitrification, ensuring the availability of nitrogen for living organisms.

Population

A group of individuals of the same species that live in a specific area and interact with each other, often studied in terms of size, density, distribution, and demographics.

Potential energy

The stored energy in an object due to its position or arrangement, such as the energy stored in a rock at the top of a hill or in chemical bonds within molecules.

Primary consumer

An organism that feeds directly on producers (plants or phytoplankton), forming the second trophic level in food chains and webs. Primary consumers are typically herbivores.

Scavengers

Animals that consume dead organisms (carrion) instead of hunting live prey, playing an important role in the decomposition process and nutrient recycling within ecosystems.

Secondary consumer

An organism that feeds on primary consumers, typically carnivores or omnivores, occupying the third trophic level in a food chain or web.

Tertiary consumer

An organism that feeds on secondary consumers, often at the top of the food chain, typically consisting of larger carnivores that have few or no natural predators.

Thermodynamics (first and second laws)

First Law

Energy cannot be created or destroyed, only transformed from one form to another. This means that the total energy in a closed system remains constant.

Second Law

Energy transformations are not 100% efficient; some energy is always lost as heat, leading to increased entropy (disorder) in the system.

Trophic level

Each step in a food chain or web, indicating the position of an organism in relation to the flow of energy and nutrients. Trophic levels typically include producers (first level), primary consumers (second level), secondary consumers (third level), and tertiary consumers (fourth level).

Zooplankton

Microscopic animals that drift in aquatic environments, serving as primary and secondary consumers by feeding on phytoplankton and other small organisms, and forming a crucial part of aquatic food webs.

Nitrogen fixation

The process by which atmospheric nitrogen (N₂) is converted into ammonia (NH₃) or related compounds by certain bacteria, making nitrogen available for uptake by plants.

Nitrification

The process by which ammonia is converted into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by bacteria, making nitrogen more accessible for plants and completing part of the nitrogen cycle.

Phosphorus cycle

The movement of phosphorus through the environment, primarily between rocks, soil, water, and living organisms. Unlike nitrogen and carbon, phosphorus does not have a gaseous phase and primarily cycles through geological and biological processes, playing a vital role in DNA, RNA, and ATP production.

Percolation

The process by which water moves downward through soil and rock layers due to gravity, filtering and purifying water as it passes through, ultimately recharging groundwater supplies.

Photosynthesis

(Already defined earlier) The process by which green plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose and oxygen, forming the foundation of energy production in most ecosystems.

Precipitation

Any form of water (rain, snow, sleet, or hail) that falls from the atmosphere to the Earth's surface, playing a key role in the water cycle and providing essential moisture for ecosystems.

Runoff

Water that flows over the land surface after precipitation, eventually entering streams, rivers, and lakes. Runoff can carry nutrients and pollutants, impacting water quality in aquatic ecosystems.