Ecology, Population Dynamics, and Environmental Sustainability

Comprehensive practice flashcards defining essential ecological concepts, population growth models, interspecific interactions, nutrient cycling pathways, and environmental sustainability from lecture notes.

Ecology

The study of interactions between living organisms and between living organisms and their environment.

Biosphere

The part of the planet that contains living organisms, including deep in the oceans, rock, air, and soil.

Ecosystem

A group of organisms that interact with each other and their environment as a unit.

Habitat

A place where an organism lives.

Population

All members of the same species living together in an area.

Community

All the different populations of plants, animals, bacteria, and fungi living together in an area.

Conservation

The wise management of our environment and existing natural resources to prevent the death and extinction of organisms.

Niche

The functional role an organism plays in an ecosystem, including where it lives, what it eats, when it is active, how it survives, and how it interacts with other organisms.

Adaptation

A structural or behavioral feature that helps an organism successfully carry out its niche and survive in its environment.

Biodiversity

The variety of life that exists in an area across all levels of biological organization.

Habitat Diversity

A measure of the number of different habitats present within an ecosystem.

Genetic Diversity

A measure of the variation of alleles present in a population within an ecosystem.

Species Diversity

The number and abundance of different species living in an ecosystem.

Pollution

Any harmful addition to the environment, such as herbicides, pesticides, or fertilisers.

Pollutant

A substance that causes pollution and damages the environment.

Deforestation

The large-scale clearing of forests for agriculture, logging, or development, resulting in habitat destruction and reduced biodiversity.

Carrying Capacity

The maximum population size that an ecosystem's available resources can support.

Abiotic Factors

Non-living environmental factors that influence ecosystems, such as soil pH, light intensity, temperature, water, and space.

Biotic Factors

Living factors that influence an ecosystem, such as competition, food availability, predation, and disease.

Producers

Autotrophic organisms, such as plants, that carry out photosynthesis to synthesize their own food.

Consumers

Heterotrophic organisms, such as animals, that obtain energy by feeding on other organisms.

Primary Consumers

Herbivores that occupy the second trophic level and feed directly on producers.

Decomposers

Microorganisms, such as bacteria and fungi, that break down dead organic matter and recycle nutrients.

Detritivores

Detritus feeders, such as earthworms, that physically ingest dead and decaying organic matter.

Detritus

Dead organic matter that accumulates in an ecosystem, including fallen leaves, plant fragments, animal remains, and waste material.

Secondary Consumers

Carnivores that feed directly on primary consumers in a food chain.

Tertiary Consumers

Carnivores that feed on secondary consumers, occupying the fourth trophic level in a food chain.

Scavengers

Animals, such as hyenas and crows, that consume the dead bodies of other animals.

Omnivores

Animals that regularly consume both plant and animal matter, such as humans, bears, and badgers.

Food Chain

A sequence of organisms showing the transfer of energy in which each organism is eaten by the next.

Grazing Food Chain

A food chain in which the initial producer is a living organism, such as grass.

Detritus Food Chain

A food chain that begins with dead organic matter, such as dead leaves, consumed by detritivores or decomposers.

Trophic Level

A feeding stage in a food chain occupied by a specific group of organisms.

Food Web

A complex network consisting of two or more interlinked food chains showing interconnected feeding relationships.

Pyramid of Numbers

An ecological diagram representing the total number of individual organisms present at each trophic level in a food chain.

Inverted Pyramid of Numbers

A pyramid of numbers where higher trophic levels outnumber lower levels, occurring when producers have massive biomass or when parasites are present.

Pyramid of Biomass

A diagram showing the total dry mass of organisms at each trophic level in a food chain, accounting for organism size.

Species Diversity Index (SDI)

A quantitative measurement of biodiversity that evaluates both species richness and species evenness in an ecosystem.

Simpson’s Diversity Index

A measure of biodiversity calculated using $D = 1 - \frac{\sum n(n-1)}{N(N-1)}$, which gives the probability that two randomly selected individuals belong to different species.

J-curve (Exponential Growth)

A population growth curve showing a rapid, unrestricted upward rise over time when resources are unlimited and limiting factors are absent.

S-curve (Logistic Growth)

A sigmoid-shaped population curve where initial rapid growth slows and stabilizes around the carrying capacity as resources become limited.

Competition

An active struggle between organisms for a resource, such as food, light, water, space, or mates, that is in scarce or limited supply.

Intra-specific Competition

Competition that takes place between individuals belonging to the same species.

Inter-specific Competition

Competition that occurs between individuals belonging to different species.

Contest Competition

A form of competition where two individuals engage in a direct physical confrontation and only one organism wins the entire resource.

Scramble Competition

A form of competition in which all competing individuals obtain a small share of the limited resource.

Predation

The biological interaction involving the catching, killing, and eating of one organism by another.

Predator

An organism that hunts, catches, kills, and feeds on another organism.

Prey

An organism that is hunted, killed, and eaten by a predator.

Parasitism

A feeding interaction where one organism obtains nutrition from a living host while causing the host physiological harm.

Parasite

An organism that lives on or inside another living organism, feeding off it and causing it harm.

Host

A living organism that is inhabited, fed on, and harmed by a parasite.

Endoparasites

Parasites, such as tapeworms or liver flukes, that inhabit the internal organs or tissues of a host organism.

Exoparasites

Parasites, such as fleas or greenflies, that live and feed on the external surface of a host organism.

Obligate Parasites

Parasites that are entirely dependent on a living host organism to complete their reproductive cycle.

Symbiosis

A close biological relationship between two organisms of different species in which at least one individual benefits.

Mutualism

A form of symbiotic relationship where both interacting species derive mutual benefit from the association.

Commensalism

A symbiotic relationship in which one organism benefits while the other is neither helped nor harmed.

Nutrient Recycling

The cyclical exchange of chemical elements, such as carbon and nitrogen, between the living and non-living components of an ecosystem.

Nitrogen Fixation

The chemical conversion of inert atmospheric nitrogen gas ($N_2$) into bioavailable compounds such as ammonia or nitrates.

Nitrification

The biological process in which chemosynthetic soil bacteria convert ammonia into nitrites, and subsequently into nitrates.

Denitrification

The biological process in which anaerobic denitrifying bacteria convert nitrates in the soil back into atmospheric nitrogen gas ($N_2$).

Eutrophication

The enrichment of aquatic environments with excess nutrients, which leads to rapid algal growth, oxygen depletion upon decomposition, and the suffocation of aquatic life.

Acid Rain

Precipitation formed when industrial emissions of sulfur dioxide dissolve in rainwater, creating sulfuric acid that lowers soil pH and impairs plant chlorophyll synthesis.

Sustainability

Meeting today's needs without compromising the ability of future generations to meet theirs, by balancing social, health, economic, and environmental priorities.