WACE ATAR Biology flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Independent variable

The factor deliberately changed or manipulated by the investigator between treatment groups, so that its effect on the measured dependent variable can be observed and compared.

Controlled variable

A factor kept constant across all treatment groups so that any observed difference in the dependent variable can be attributed to the independent variable rather than a confounder.

Validity

The extent to which a test or investigation measures what it claims to measure, achieved by controlling confounders, using appropriate techniques and selecting a representative sample.

Reliability

The consistency of repeated measurements or trials under the same conditions; it is improved by repeated trials, larger sample sizes and standardised procedures.

Accuracy versus precision

Accuracy is how close a measurement is to the true value, affected by systematic error; precision is how close repeated measurements are to each other, affected by random error.

Null hypothesis

A statement that there is no significant difference between groups or no association between variables; statistical tests estimate the probability of the data if it were true.

Standard error of the mean

A measure of uncertainty in an estimated mean, calculated as the standard deviation divided by the square root of the sample size; it decreases as sample size grows.

Random sampling

A sampling method in which every individual in the population has an equal chance of selection, reducing selection bias and improving how well the sample represents the population.

Peer review

Independent scrutiny of a manuscript by experts in the field before publication; it checks methods, analysis and interpretation, filtering poor work but not guaranteeing correctness.

Scientific theory

A well-supported explanatory framework that has survived repeated testing and is consistent with accumulated evidence, distinct from a hypothesis or an unsupported guess.

Provisional nature of science

Scientific claims are open to revision when new evidence, better instruments or reanalysis appear, so accepted knowledge represents current best evidence rather than final certainty.

Conflict of interest

A situation where financial, commercial or personal interests could bias the design, interpretation or reporting of research; managed by disclosure and independent replication.

Open data sharing

Public release of research data so other groups can verify findings and reuse information, which accelerated projects such as the Human Genome Project and vaccine development.

Indigenous ecological knowledge

Long-term observations and land management practices held by Indigenous peoples, increasingly combined with Western science in fire management, conservation and species monitoring.

Genetic diversity

The variety of alleles within and among populations of a species; higher diversity improves the capacity of populations to adapt to environmental change and resist disease.

Species richness

The number of different species present in a defined community or area, one component of biodiversity that does not account for how evenly individuals are distributed.

Species evenness

How similar the abundances of species in a community are; a community with equal abundances has high evenness even if species richness is low.

Keystone species

A species whose influence on community structure is disproportionately large relative to its abundance; its removal causes cascading changes in other populations.

Trophic efficiency

The proportion of energy at one trophic level transferred to the next, typically about ten percent, with the remainder lost mainly as heat through respiration.

Carrying capacity

The maximum population size an environment can sustain indefinitely given available resources; symbol K in the logistic growth equation, where growth slows as N approaches K.

Primary succession

The sequence of community change beginning on newly formed substrate without soil, such as bare rock or lava, where colonising pioneer species must first build soil.

Secondary succession

Community change following a disturbance that leaves soil and propagules intact, such as after fire or abandonment of farmland, typically proceeding faster than primary succession.

Mutualism

A symbiotic relationship in which both participating species benefit, for example nitrogen-fixing bacteria in root nodules receiving carbohydrates while supplying usable nitrogen.

Prokaryote versus eukaryote

Prokaryotes lack a membrane-bound nucleus and organelles and are typically smaller; eukaryotes have a nucleus, mitochondria and internal membrane-bound compartments.

Surface area to volume ratio

The ratio of a cell's membrane area to its volume; it falls as cells enlarge, limiting diffusion, which constrains cell size and drives compartmentalisation in large cells.

Mitosis

Nuclear division producing two daughter cells genetically identical to the parent cell, used for growth, repair and asexual reproduction in diploid organisms.

Meiosis

Two successive nuclear divisions producing four haploid gametes that are genetically distinct because of crossing over in prophase I and independent assortment in metaphase I.

Codominance

A situation where both alleles in a heterozygote are fully expressed in the phenotype, illustrated by AB blood type where A and B antigens both appear.

Incomplete dominance

A situation where the heterozygote shows an intermediate phenotype between the two homozygotes, such as pink flowers from red and white parents.

Genetic drift

Random change in allele frequencies due to chance, strongest in small populations; founder and bottleneck effects are examples that reduce genetic diversity.

Hardy-Weinberg equilibrium

A model in which allele and genotype frequencies stay constant across generations if there is no mutation, migration, selection or drift and mating is random; genotypes follow p squared plus 2pq plus q squared.