Mr G Science chapter 2 notes

Abiotic factor

Non-living physical or chemical element of an ecosystem (e.g., temperature, light, pH).

Biotic factor

Living component of an ecosystem affecting organisms (e.g., predators, competition).

Population

Group of individuals of the same species living in a specific area.

Population density

Number of individuals per unit area.

Natality

Birth rate in a population.

Mortality

Death rate in a population.

Limiting factors

Environmental factors that restrict population growth (e.g., food, water, space).

Carrying capacity (K)

Maximum population size an environment can sustainably support.

Biotic potential

Maximum reproductive capacity of a population under ideal conditions.

r-selected species

Species with many offspring, low parental care, rapid growth (e.g., insects).

K-selected species

Species with few offspring, high parental care, populations near carrying capacity (e.g., elephants).

S-curve

Population growth that slows and stabilizes at carrying capacity due to limiting factors.

J-curve

Exponential population growth without leveling off, usually unsustainable.

Fundamental niche

Full potential habitat of a species without competition or limiting factors.

Realized niche

Actual habitat occupied by a species, limited by competition or other factors.

Predation

One species hunts and eats another.

Herbivory

Animal feeds on plants.

Parasitism

One organism benefits, other is harmed.

Mutualism

Both species benefit.

Competition

Species compete for the same limited resource, harming both.

Energy flow

Transfer of energy through trophic levels in an ecosystem.

Producers

Autotrophs that create organic matter from sunlight or chemicals.

Consumers

Organisms that eat producers or other consumers for energy.

Decomposers

Organisms that break down dead matter (e.g., fungi, bacteria).

Bioaccumulation

Build-up of toxins in an organism over time.

Biomagnification

Increase in toxin concentration at higher trophic levels.

Denitrification

Bacteria convert nitrates into nitrogen gas, returning N₂ to atmosphere.

Nitrogen fixation

Conversion of nitrogen gas into nitrates by bacteria or lightning.