APES 1st Semester Final Study Guide - Definitions

Mutation

A change in the DNA sequence of an organism's genome, leading to variations in traits.

Natural Selection

The process by which individuals with favorable traits are more likely to survive and reproduce.

Artificial Selection

The intentional breeding of organisms with desirable traits by humans.

Adaptation

A trait that enhances an organism's ability to survive and reproduce in its environment.

Divergent Evolution

The process by which related species evolve different traits due to differing environments or selective pressures.

Speciation

The process by which new species arise from existing species.

Selective Pressure

Environmental factors that influence which individuals in a population survive and reproduce.

Niche

The role or function of an organism within its ecosystem.

Habitat

The physical environment in which an organism lives.

Generalist Species

Organisms that can thrive in a wide variety of environmental conditions.

Specialist Species

Organisms that have specific habitat requirements and diet.

Endemic Species

Species that are native to and found only within a specific geographic area.

Invasive Species

Non-native species that outcompete native species for resources.

Keystone Species

A species that has a disproportionately large impact on its ecosystem.

Indicator Species

Species whose presence reflects the health of an ecosystem.

Resource Partitioning

The process by which similar species reduce competition by using different resources.

Symbiotic Relationships

Interactions between two different species living together.

Mutualism

A symbiotic relationship where both species benefit.

Commensalism

A symbiotic relationship where one species benefits, and the other is neither helped nor harmed.

Parasitism

A symbiotic relationship where one species benefits at the expense of the other.

Primary Succession

The establishment of a biological community in an area that has never been colonized.

Secondary Succession

The re-colonization of an area after a disturbance that did not eliminate all life.

Species Diversity

The variety of different species in an ecosystem, including species richness and evenness.

Species Richness

The number of different species in an ecosystem.

Species Evenness

The relative abundance of each species in an ecosystem.

Habitat Fragmentation

The process of breaking up large habitats into smaller, isolated patches.

Threatened Species

Species that are likely to become endangered in the near future.

Endangered Species

Species that are at serious risk of extinction.

Habitat destruction, Invasive species, Pollution, Population (human), Climate change, Overexploitation

HIPPCO

Population Size

The total number of individuals in a population.

Population Density

The number of individuals per unit area or volume.

Random Dispersion

Individuals are spaced unpredictably.

Uniform Dispersion

Individuals are evenly spaced.

Clumped Dispersion

Individuals are grouped in patches.

Age Structure

The distribution of individuals of different ages within a population.

Pre-Reproductive Age Group

Individuals not yet capable of reproduction.

Reproductive Age Group

Individuals capable of reproduction.

Post-Reproductive Age Group

Individuals beyond their reproductive years.

Biotic Potential

The maximum reproductive capacity of an organism under optimal conditions.

Intrinsic Rate of Growth (r)

The rate at which a population increases, calculated based on birth rate minus death rate.

Logistic Growth

A population growth model that levels off as it approaches carrying capacity (K).

Carrying Capacity (K)

The maximum number of individuals an environment can sustainably support.

Environmental Resistance

The sum of environmental factors that limit population growth.

Habitat Corridors

Strips of natural habitat that connect isolated populations.

Immigration

Movement of individuals into a population.

Emigration

Movement of individuals out of a population.

Zero Population Growth

A situation where births plus immigration equal deaths plus emigration.

Replacement Level Fertility

The average number of children each woman needs to have to maintain a stable population size.

Total Fertility Rate

The average number of children a woman would have during her lifetime.

Sustainability

The ability to meet the needs of the present without compromising future generations' ability to meet their own needs.

Sustainable Yield

The rate at which a resource can be harvested without depleting its stock, ensuring it regenerates over time.

GDP (Gross Domestic Product)

The total monetary value of all goods and services produced within a country's borders in a specific time period.

Per Capita GDP

GDP divided by the total population of a country, providing average economic output per person.

Developed Nations

Countries with high levels of industrialization, high incomes, and high standards of living.

Developing Nations

Countries with lower levels of industrialization, lower incomes, and lower standards of living.

Tragedy of the Commons

A situation where individuals acting in self-interest deplete a shared resource, leading to its degradation.

Open Access Resource

Resources available to all individuals without restrictions, leading to potential overuse.

Renewable Resources

Resources that can be replenished naturally over time, like solar energy and forests.

Nonrenewable Resources

Resources that do not replenish at a sustainable rate, such as fossil fuels.

Point Source Pollutants

Single, identifiable sources of pollution, for example, a factory discharge pipe.

Nonpoint Source Pollutants

Diffuse sources of pollution, such as runoff from agricultural fields.

Anthropogenic

Environmental changes or pollution that result from human activity.

Biodegradable

Substances that can be broken down by natural processes, like food waste.

Nondegradable

Substances that cannot be broken down by natural processes, such as plastics.

Entropy

A measure of disorder or randomness in a system, associated with the second law of thermodynamics.

NPP (Net Primary Productivity)

The rate at which plants produce biomass after accounting for energy used in respiration.

GPP (Gross Primary Productivity)

The total energy produced by photosynthesis in an ecosystem before energy use for respiration.

Respiration

The process by which organisms convert glucose and oxygen into energy, releasing carbon dioxide.

Biological Oxygen Demand (BOD)

A measure of the amount of oxygen that microorganisms consume while decomposing organic matter.

Ecological Efficiency

The percentage of energy transferred from one trophic level to the next in an ecosystem, typically around 10%.

Synergy

The interaction of two or more agents or forces such that their combined effect is greater than the sum of their individual effects.

Time Delays

The lag between an action and its observable effects in an ecosystem, complicating management.

Tipping Points

Thresholds beyond which a system can change dramatically and irreversibly.

Prokaryotic

Simple, unicellular organisms without a nucleus, such as bacteria.

Eukaryotic

Complex organisms with cells that contain a nucleus and organelles, including plants and animals.

Abiotic

Non-living components of an ecosystem such as water, soil, and climate.

Biotic

Living components of an ecosystem such as plants, animals, and microorganisms.

Range of Tolerance

The range of environmental conditions an organism can withstand before experiencing stress.

Limiting Factors

Environmental conditions that restrict the growth or distribution of an organism.

Trophic Level

The position an organism occupies in a food chain, determining its feeding relationships.

Autotroph

Organisms that produce their own food through photosynthesis or chemosynthesis.

Heterotroph

Organisms that rely on consuming other organisms for food.

Decomposers

Organisms that break down dead organic matter, recycling nutrients back into the ecosystem.

Biomagnification

The increasing concentration of toxic substances in organisms at higher trophic levels.

Bioaccumulation

The accumulation of substances in an organism over its lifetime.

Transpiration

The process by which water is absorbed by plants and released as vapor through stomata.

Infiltration

The process by which water enters the soil from the ground surface.

Percolation

The movement of water through soil and porous rock, filtering and purifying water.

Nitrogen-Fixing

Nitrogen gas (N2) in the atmosphere is converted into ammonia (NH3) by nitrogen-fixing bacteria in the soil, making it usable by plants

Assimilation

Plants absorb the fixed nitrogen (ammonia or nitrate) from the soil and incorporate it into their tissues

Nitrification

Bacteria convert ammonia into nitrite (NO2-) and then nitrate (NO3-) which is readily available to plants

Ammonification

When organisms die or excrete waste, decomposers break down organic nitrogen compounds into ammonia

Denitrification

Certain bacteria convert nitrate back into nitrogen gas, returning it to the atmosphere

Nitrogen fixation—> Assimilation—> Ammonification—> Nitrification—> Denitrification

Order of the Nitrogen Cycle

Permeability

The ability of soil to allow water to pass through it

Water-Holding Capacity

The ability of soil to retain moisture

Loam

A soil that is a balanced mixture of sand, silt, and clay, ideal for agriculture due to its good drainage and nutrient-holding capacity.

Humus

Decomposed organic matter that enriches soil fertility, improves structure, and enhances moisture retention.

Conventional Tillage

Involves plowing and turning the soil, which can increase erosion.

Conservation Tillage

Reduces soil disturbance, leaving crop residues to protect the soil.