WJEC A-level Biology Unit 2.1 Vocabulary

Vocabulary flashcards covering core definitions, ecological sampling, classification, and conservation concepts from WJEC A-level Biology Unit 2.1.

Biodiversity

The variety of different species and the number of individuals within those species in an area.

Species

A group of organisms that can interbreed under natural conditions to produce fertile offspring.

Endemic species

A species found only in a particular geographical area.

Invasive species

A non-native organism introduced to an area that spreads and can harm native species or habitats.

Bimodal distribution

A distribution where the curve has two peaks.

Quadrat

A sampling tool used to estimate the abundance or percentage cover of organisms in a defined area.

Transect

A sampling line used to investigate how the distribution or abundance of species changes across an environmental gradient.

Line transect

A transect method that records organisms touching or occurring along a line.

Belt transect

A transect method that samples an area along the line using quadrats.

Kick sampling

A stream sampling method where the net is placed downstream on the stream bed and stones upstream are kicked so disturbed organisms drift into the net.

Simpson's Diversity Index

A measure of diversity calculated using the formula $D = 1 - \frac{\Sigma n(n - 1)}{N(N - 1)}$, where higher values indicate greater diversity.

Classification hierarchy

The taxonomic rank sequence: Domain $\rightarrow$ Kingdom $\rightarrow$ Phylum $\rightarrow$ Class $\rightarrow$ Order $\rightarrow$ Family $\rightarrow$ Genus $\rightarrow$ Species.

Phylogenetic tree

A branching diagram that shows evolutionary relationships and common ancestry, where each branching point represents a common ancestor.

Homologous structures

Structures that possess a similar underlying structure, but perform different functions.

Analogous structures

Structures that possess a similar function, but have a different underlying structure.

Biological control

The use of a living organism to reduce the growth or numbers of a pest or invasive species.

Wildlife corridors

Connections of native vegetation (such as trees) that link isolated habitat patches to allow animals to move, access resources, and breed.

Critically endangered species

Organisms that face an extremely high risk of extinction in the wild.