VCE Biology Unit 4 Area of Study 2 Practice Flashcards

Vocabulary practice flashcards generated from VCE Biology Unit 4 Area of Study 2 lecture notes and case study materials.

Sympatric Speciation

The evolution of a new species from an ancestral population without geographic isolation, occurring while populations continue to share the same physical space.

Resident Killer Whales

A fish-eating ecotype of Orcinus orca in the Pacific Northwest that feeds up to 80-90% on Chinook salmon, lives in large matrilineal pods of 10-40+ animals, and uses frequent, loud echolocation.

Bigg's (Transient) Killer Whales

A mammal-eating ecotype of Orcinus orca in the Pacific Northwest that feeds on seals, sea lions, and porpoises, lives in small fluid groups of 2-7 animals, and hunts using silent stalking.

Incomplete Lineage Sorting

A genomic phenomenon where different regions of the genome reveal different evolutionary histories, making speciation trees difficult to resolve with certainty.

Cranial Capacity

The internal volume of the braincase measured in cubic centimetres ($\text{cc}$ or $\text{cm}^3$), used as a proxy for brain size in hominin fossil analysis.

Homo naledi

A hominin species discovered in South Africa's Rising Star Cave, dated to 236,000-335,000 years ago, displaying a small cranial capacity ($465\text{--}610\,\text{cc}$) combined with modern Homo-like limbs for walking and manipulation.

Introgression

The transfer of genetic material between species or populations through interbreeding, such as the acquisition of Neanderthal and Denisovan DNA in modern human populations.

Sahul

The ancient landmass uniting Australia, New Guinea, and Tasmania during periods of lower sea levels.

Prehensile Hands and Feet

Grasping digits common to primates, featuring five digits, an opposable digit, and flat fingernails instead of claws.

Hominoidea

A primate superfamily (hominoids) characterised by a shorter spine, lack of a tail, broader ribcage and pelvis, increased cranium size, and distinctive lower molar teeth.

Expensive Brain Hypothesis

An evolutionary theory proposing that increased brain size provides cognitive and social benefits but requires higher energy input, driving changes in diet and food production.

Out of Africa Hypothesis

The model proposing that modern Homo sapiens first evolved in Africa before migrating outwards across Eurasia, replacing earlier hominin species.

Multiregional Hypothesis

The model proposing that modern Homo sapiens evolved concurrently in multiple regions across the world from regional populations of Homo erectus.

Silent Mutation

A point mutation in which a nucleotide substitution changes a codon to one that codes for the exact same amino acid, leaving the polypeptide chain unaltered.

Missense Mutation

A point mutation in which a nucleotide substitution alters a codon to code for a different amino acid, changing the resulting polypeptide chain.

Nonsense Mutation

A point mutation where a nucleotide substitution creates a premature STOP codon, prematurely halting translation and resulting in a shortened protein.

Frameshift Mutation

An insertion or deletion of one or two nucleotides that alters the reading frame of DNA codons, causing major disruptions to protein structure and function.

Horizontal Gene Transfer

The direct transfer of genetic material between organisms other than vertical transmission from parent to offspring, commonly seen in prokaryotes.

Genetic Drift

Random fluctuations in allele frequencies within a population over time, having its most pronounced impact on small populations.

Bottleneck Effect

A form of genetic drift occurring when a severe, random reduction in population size drastically eliminates alleles and reduces genetic diversity.

Founder Effect

A form of genetic drift occurring when a small, unrepresentative group breaks off from a larger main population to establish a new population with reduced genetic diversity.

Natural Selection

The evolutionary process where environmental selection pressures favour individuals with advantageous phenotypes, increasing their biological fitness and shifting allele frequencies.

Biological Fitness

A measure of an organism's capacity to survive, reproduce, and pass its advantageous alleles to the next generation within its specific environment.

Allopatric Speciation

The divergence of populations into distinct species caused by geographical isolation that completely prevents gene flow.

Antigenic Drift

Small, gradual mutations in the genes encoding viral surface antigens over time, requiring periodic adjustments in host immunological memory.

Antigenic Shift

Sudden and major mutations or genomic recombinations encoding viral surface antigens, capable of triggering epidemics or pandemics.

Index Fossil

A widespread fossil of a species that existed for a short, known period of time, used as a reference point to correlate and determine the relative age of unknown rock strata.

Radiometric Dating

An absolute dating method that calculates the exact age of rock or fossil specimens by measuring the ratio of unstable radioisotopes to their stable decay products.

Half-Life

The amount of time required for half of the initial mass of a radioisotope to decay into stable daughter products.

Stromatolites

Layered sedimentary rock structures formed by the mineral-trapping activity of photosynthetic prokaryotes, specifically cyanobacteria.

Cambrian Explosion

A period of rapid diversification of multicellular life characterised by the evolutionary appearance of hardened body parts like shells and bones.

Homologous Structures

Anatomical traits present in different species that share a common evolutionary ancestry and structural layout, but serve different functions due to divergent evolution.

Analogous Structures

Anatomical traits in different species that perform similar functions but evolved independently without a recent common ancestor, reflecting convergent evolution.

Vestigial Structures

Anatomical remnants that have lost their original ancestral function over evolutionary time.

Molecular Clock

A model that estimates evolutionary divergence time based on the concept that heritable gene and protein mutations accumulate at a relatively steady rate over time.

Mitochondrial DNA (mtDNA)

Circular DNA located inside mitochondria that is inherited purely through the maternal line without genetic recombination.