Ecology & Population Practice Test Vocabulary

Vocabulary flashcards covering core ecological concepts, population growth models, ecosystem spheres, food web dynamics, experimental design variables, and population density calculations.

Abiotic Factor

A nonliving part of an ecosystem, such as temperature, water, sunlight, soil pH, or an office building.

Biotic Factor

A living part of an ecosystem, such as plants, animals, bacteria, predators, human, or food availability.

Biosphere

The Earth sphere that includes all living organisms.

Geosphere

The Earth sphere that includes Earth's rocks, minerals, and land.

Optimal Range

The specific range of environmental conditions, such as between $20 proposal^\text{C}$ and $25^\text{C}$, in which an organism or population grows best.

Population

All the members of one species living in the same area.

Community

Several populations of different species living and interacting in the same area.

Habitat

The physical place where an organism lives.

Fundamental Niche

The full range of conditions and resources an organism could theoretically use to survive without competition.

Realized Niche

The actual resources and environmental conditions an organism uses because of environmental interactions such as competition and predation.

Random Distribution

A population dispersion pattern where individuals are scattered with no obvious pattern, such as trees in a field.

Clumped Distribution

A population dispersion pattern where individuals are packed closely together in groups around available resources, such as penguins around food.

Uniform Distribution

A population dispersion pattern where individuals are evenly spaced apart due to direct competition for territory or resources.

Population Growth Equation

The mathematical equation representing population change: $\text{Population Growth} = \text{Births} - \text{Deaths} + \text{Immigration} - \text{Emigration}$.

Population Equilibrium

A state where population growth equals $0$ because total gains from births and immigration equal total losses from deaths and emigration.

Exponential Growth

Rapid population growth that occurs without major limits, producing a J-shaped curve.

Logistic Growth

Population growth that begins rapidly but slows as limiting factors increase and levels off around carrying capacity, producing an S-shaped curve.

Carrying Capacity

The maximum population size an environment can sustainably support.

Producer

An organism located at the first trophic level of a food chain (such as grass) that generally has the most available energy.

Primary Consumer

An organism at the second trophic level that consumes producers, such as a rabbit in a grass $\rightarrow$ rabbit $\rightarrow$ fox chain.

Ten Percent Rule

The principle that approximately $10\%$ of energy is transferred from one trophic level to the next in a food chain.

Independent Variable

The variable tested or manipulated by a scientist in an experiment, such as the amount of fertilizer given to plants.

Dependent Variable

The variable measured in response to changes in an experiment, such as plant height measured after $30\,\text{days}$.

Constant

A factor kept unchanged across all experimental conditions to ensure a controlled test, such as keeping the type of plant identical.

Control Group

A baseline group in an experiment that does not receive the experimental treatment, serving as a comparison for the experimental group.

Population Density

The measurement of population per unit area, calculated as $\text{Population Density} = \frac{\text{Number of organisms}}{\text{Area}}$, yielding $2\,\text{deer/km}^2$ for $600\,\text{deer}$ in $300\,\text{km}^2$.