IB Environmental systems and societies 2.2 Energy and Biomass in Ecosystems Key Definitions

Autotrophs are organisms that can synthesize their own food from inorganic sources of carbon (typically carbon dioxide, CO₂) and other essential elements.

Bioaccumulation refers to the process by which the concentration of non-biodegradable pollutants increases in an organism over time.

Biomass is the total mass of living organisms in a given area or volume.

Cellular respiration is the conversion of stored chemical energy in glucose into a usable chemical form that fuels metabolic processes in living cells.

Chemoautotrophs are organisms that use inorganic chemical reactions to obtain energy, typically through exothermic reactions, to drive the process of chemosynthesis.

Consumers are organisms that obtain energy by feeding on other organisms.

Consumers are organisms that obtain chemical energy by consuming other organisms or organic material.

Decomposers, such as fungi and bacteria, are organisms that break down organic matter into simpler substances.

Detritivores are organisms that feed on dead organic matter, such as decaying plants and animals.

Ecological efficiency refers to the percentage of energy that is transferred from one trophic level to the next in an ecosystem.

Ecological pyramids are graphical representations used to show the relative numbers, biomass, or energy at different trophic levels in an ecosystem.

Entropy refers to the measure of disorder or randomness within a system.

The First Law of Thermodynamics states that energy cannot be created or destroyed. It only changes from one form to another, maintaining a constant total amount.

A food chain is a linear sequence that shows how organic matter and energy flow from one organism to another.

Food webs are networks of interconnected food chains that show how energy and matter flow through an ecosystem.

Gross Primary Productivity (GPP) refers to the total amount of energy captured by producers (typically plants and algae) through photosynthesis.

Gross Productivity (GP) refers to the total amount of biomass produced by an organism or a trophic level over a given period of time.

Herbivores are animals that feed primarily on plants or algae.

Heterotrophs are organisms that cannot synthesize their own food. Instead, they obtain carbon compounds (such as glucose, proteins, and lipids) by consuming other organisms, either autotrophs (plants and algae) or other heterotrophs (animals, fungi, etc.).

Maximum sustainable yield (MSY) is the largest amount of biomass that can be harvested from an ecosystem without depleting its resources, ensuring long-term sustainability.

Microplastics are small plastic particles, typically less than 5 millimeters in diameter, that result from the breakdown of larger plastic waste or are intentionally manufactured at that size.

Net Primary Productivity (NPP) refers to the amount of carbon that is captured by plants through photosynthesis and is available for growth and reproduction after subtracting the energy used by the plants for cellular respiration.

Net Productivity (NP) is the amount of biomass remaining after the losses due to cellular respiration have been subtracted from the gross productivity.

Nutrient cycling is the movement of nutrients like nitrogen, phosphorus, and carbon through the soil, plants, and atmosphere.