IB Environmental Systems and Societies Topic 2: Ecology

Species

a group of organisms sharing common characteristics that can interbreed and produce offsprings that can also interbreed and produce young.

Population

a group of organisms of the same species living in the same area at the same time, and which are able to interbreed.

Habitat

the environment in which a species normally lives

Niche

where ,when and how an organism lives.

Fundamental Niche

full potential of where, when and how a species can exist.

Realized Niche

where, when how the species actually exist.

Abiotic Factors

non-living parts of the environment. Such as factors that determine the fundamental and realized niche.

Biotic Factors

the living part of the environment. Interactions between organisms are also [...].

Predation

when one animal hunts and eats another organism

Predator-Prey Relationship

The interaction between predator and prey.

Herbivory

an interaction where an animal feeds on plant.

Parasitism

an organism that benefits at the expense of another from which it derives food.

Pathogen

An organism that causes disease

Mutualism

when both species benefit from the relationship.

Intraspecific Competition

competition within the same species

Interspecific Competition

competition between different species.

S-Population Curve

a curve that shows initial rapid growth and then slows down as the carrying capacity is reached.

J-Population Curve

curve where the exponential growth is an increasing or accelerating rate of growth.

Limiting Factors

factors that limit the distribution or numbers of a particular population. [...] within the environment tend to slow down population growth.

Community

many species living together.

Ecosystem

a community of interdependent organisms and the physical environment they inhabit.

Photosynthesis

the flow where light energy is converted into chemical energy and is then stored in biomass.

Respiration

the conversion of organic matter into carbon dioxide and water in all living organisms releasing energy.

Producers

an organism that is able to produce its own food from inorganic substances.

Consumers

organisms that cannot make their own food eat other organisms to obtain energy and matter.

Decomposers

organisms that obtain their food and nutrients from the breakdown of dead organic matter.

Trophic Level

the position that an organism occupies in the food chain

Pyramid of Numbers

the model that records the number of individuals at each trophic level coexisting in an ecosystem.

Pyramid of Biomass

the model that represents the biological mass of the standing stock at each trophic.

Pyramid of Productivity

shows that flows of energy through each trophic level of the food chain over a period of time.

Bioaccumulation

the retention or build-up of non-biodegradable or slowly biodegradable chemicals in the body.

Biomagnification

the process whereby the concentration of a chemical increases at each trophic level.

Primary Productivity

the gain by producers in energy or biomass per unit area per unit time.

Secondary Productivity

the biomass gained by heterotrophic organisms through feeding and absorbed, measured in units of mass or energy per unit area per unit time.

Gross Productivity

the total gain in energy or biomass per unit area per unit time.

Net Productivity

the gain in energy or biomass per unit area per unit time remaining after allowing for respiratory losses.

Gross Primary Productivity

the mass of glucose created by photosynthesis per unit area per unit time in primary producers.

Net Primary Productivity

the gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses.

Gross Secondary Productivity

the total energy or biomass assimilated by consumers and is calculated by subtracting the mass of faecal loss from the mass of food consumed.

Net Secondary Productivity

the gain by consumers in energy or biomass per unit area per unit time remaining after respiratory loss.

Maximum Sustainable Yield

the maximum flow of a given resource such that the stock does not decline over time.

Biomes

collections of ecosystems sharing similar climatic conditions.

Insolation

the amount of solar radiation reaching a given area.

Precipitation

rain, snow or hail

Climate Change

refers to the rise in average surface temperatures on Earth

Succession

the change over time in an ecosystem involving pioneer, intermediate, and climax communities.

Diversity

It is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet.

r-Strategist Species

species that grow and mature quickly, have small offspring

K-Strategist Species

species that grow gradually and produce few but large offspring that also mature slowly.

C- Strategist Species

species that lie between r-strategist Species and K-strategist Species.

PH

is a measure of hydrogen ion concentration; a measure of the acidity or alkalinity of a solution.

Temperature

the degree or intensity of heat present in a substance or object

Turbidity

the cloudiness or haziness of fluid, it affects the penetration of sunlight into water and rates of photosynthesis.

Population Density

the number of individuals of each species per unit area.

Species Diversity

number of species and their relative abundance in a given area or sample.