Science Test

Population

All individuals of a single species living in a specific area at the same time

Community

All the different populations of living organisms (biotic factors) interacting in a given area

Ecosystem

A biological community plus all the non-living (abiotic) factors in that area

Habitat

The specific physical environment or place where an organism normally lives and finds resources

Biotic Factor

The living components of an ecosystem (e.g., plants, animals, fungi, bacteria, viruses)

Abiotic Factor

The non-living physical and chemical elements of an ecosystem (e.g., sunlight, temperature, rainfall, dissolved oxygen)

Commensalism

A symbiotic relationship where one organism benefits and the other is unaffected (+/0)

Mutualism

A symbiotic relationship where both organisms benefit (+/+)

Parasitism

A symbiotic relationship where one organism benefits and the other is harmed (+/-)

Intraspecific Competition

Competition for resources between members of the same species

Producer (Autotroph)

An organism that makes its own food using sunlight or chemical energy (e.g., plants, algae)

Consumer (Heterotroph)

An organism that cannot make its own food and must obtain energy by eating other organisms

Decomposer / Detritivore

An organism (like fungi, bacteria, or earthworms) that breaks down dead organic matter and returns nutrients to the soil

Predator

An animal that naturally hunts, kills, and feeds on other organisms (prey)

Primary Consumer

An organism that eats producers (herbivores)

Secondary Consumer

An organism that eats primary consumers (carnivores or omnivores)

Tertiary / Quaternary Consumer

Carnivores at higher trophic levels that feed on other consumers

Trophic Level

The hierarchical position or feeding level an organism occupies in a food chain or food web

Food Chain

A single, linear sequence showing the direct flow of energy from one organism to another

Food Web

A complex network of interconnected food chains representing all feeding relationships in an ecosystem

10% Rule (Energy Pyramid)

Only about 10% of energy is transferred from one trophic level to the next; the rest is lost as heat

Energy Transfer Calculation Example

If a producer makes 35,000 kJ, primary consumers get 3,500 kJ, secondary get 350 kJ, and tertiary get 35 kJ

Carrying Capacity

The maximum population size of a species that a specific environment can sustainably support over time

Limiting Factor

An environmental factor (biotic or abiotic) that restricts or limits the growth, abundance, or distribution of a population

Photosynthesis Equation

Carbon dioxide + Water \rightarrow Glucose + Oxygen (requires sunlight)

Cellular Respiration Equation

Glucose + Oxygen \rightarrow Carbon dioxide + Water + Energy (ATP)

Relationship Between Photosynthesis & Respiration

Complementary processes: the products of photosynthesis (glucose + O_2) are the reactants for cellular respiration, and vice versa

Atmosphere

Earth's sphere containing all the gases surrounding the planet (air)

Hydrosphere

Earth's sphere containing all water (oceans, lakes, groundwater, rivers)

Lithosphere

Earth's rigid outer layer containing rocks, minerals, and bedrock

Biosphere

The global sum of all ecosystems; the zone of life on Earth

Infiltration

Water soaking downward from the surface into the soil and groundwater

Transpiration

The process where plants absorb water through roots and release water vapor through pores in leaves

Surface Run-off

Water that flows over the land surface rather than soaking into the ground

Nitrogen Fixation & Nitrification

Bacterial processes that convert unreactive atmospheric nitrogen (N_2) into usable forms like nitrates and ammonia for plants

Assimilation

The process by which plants absorb and incorporate usable nitrogen compounds into organic molecules

Algal Bloom

A rapid increase of phytoplankton/algae caused by excess nutrient runoff (like fertilizer), leading to oxygen depletion in water bodies

Carbon Sink

A reservoir (such as forests or oceans) that absorbs more carbon dioxide from the atmosphere than it releases

Carbon Source

A process or reservoir that releases more carbon dioxide into the atmosphere than it absorbs (e.g., burning fossil fuels, traffic emissions)

Bioaccumulation

The accumulation of toxic substances or heavy metals (like lead or mercury) in a single organism's body over its lifetime

Biomagnification

The increase in concentration of toxins at higher trophic levels as apex predators consume many contaminated prey items

Impact of Toxins in Plants (e.g., Lead in Cactus)

Apex predators/top carnivores at the highest trophic level will be most heavily impacted due to biomagnification

Crop Rotation

The practice of growing a series of different types of crops in the same area across seasons to improve soil health and nutrient cycling

Agroforestry

The intentional integration of trees and shrubs into crop and animal farming systems to provide shade, wind protection, and biodiversity

Cover Crops

Plants sown to cover topsoil rather than for harvest, used to manage soil erosion, fertility, and quality