B4.2 Niches (SL)

Vocabulary flashcards covering key terms related to ecological niches, modes of nutrition, respiratory strategies, and adaptive traits discussed in the lecture notes.

Ecological niche

The functional position and role of a species within its environment, including all abiotic and biotic interactions needed for survival.

Abiotic factors

Non-living environmental components such as sunlight, temperature and oxygen that influence an organism's niche.

Biotic factors

Living components of an ecosystem such as food source, competition and activity patterns that shape an organism's niche.

Competitive exclusion

When two species compete for identical resources, the more efficient one drives the other to local extinction.

Resource partitioning

The division of resources or habitats by competing species so both can coexist.

Fundamental niche

The full range of environmental conditions a species could occupy in the absence of competitors.

Realized niche

The actual portion of the niche a species occupies after interactions with other organisms.

Obligate anaerobe

Organism that respires without oxygen and cannot survive in its presence.

Obligate aerobe

Organism that requires oxygen for aerobic respiration and cannot live without it.

Facultative anaerobe

Organism capable of switching between aerobic and anaerobic respiration depending on oxygen availability.

Autotrophic nutrition

Mode of nutrition in which organisms manufacture organic molecules from CO₂ using an external energy source.

Heterotrophic nutrition

Mode of nutrition where organisms obtain organic compounds by consuming other organisms.

Photosynthesis

Autotrophic process that uses light energy to convert CO₂ and water into organic molecules.

Chemosynthesis

Autotrophic process that uses energy from chemical reactions to synthesize organic compounds.

Saprotrophic nutrition

Heterotrophic mode in which decomposers secrete enzymes onto dead organic matter and absorb the digested products.

Holozoic nutrition

Heterotrophic mode where food is ingested, internally digested, absorbed and assimilated.

Mixotrophic nutrition

Combination of autotrophic and heterotrophic nutrition used by some protists such as Euglena.

Phototroph (archaea)

Archaeon that derives ATP from light-driven reactions.

Lithotroph

Archaeon that gains energy from oxidation of inorganic compounds.

Organotroph

Archaeon that obtains energy by breaking down organic compounds.

Methanogenesis

Unique archaeal process that produces methane as a metabolic by-product.

Liana

Woody vine adapted to climb host trees to reach sunlight in forest canopies.

Overstory tree

Emergent tree that grows above the main forest canopy to access light.

Understory plant

Shade-adapted herb or shrub with large leaves that grows beneath the canopy.

Epiphyte

Plant that grows on another plant’s branches for support without rooting in soil.

Spines / thorns

Physical plant defenses that deter herbivore ingestion.

Mandibles

Specialized insect mouthparts adapted for biting or chewing plant material.

Ruminant gut flora

Microbial community in herbivore stomachs that produces enzymes for digesting plant cellulose.

Camouflage

Prey adaptation that allows an organism to blend with its environment to avoid detection.

Mimicry

Prey strategy in which an organism resembles another species or object to deter predators.

Predator claws and teeth

Sharp anatomical adaptations enabling carnivores to catch and tear prey.

Dentition

Arrangement and type of teeth used to infer diet; broader molars in herbivores, sharp canines in carnivores/omnivores.