BIOL 1010 | Midterm Definitions

Chapters: 1, 13, 14, 15, 16, 17, 18, 19

biology

The scientific study of life and living organisms.

life

The condition that separates living organisms (plants, animals, etc.) from nonliving matter, characterized by growth, reproduction, functional activity, and ongoing change until death.

cell

The basic structural and functional unit of life; all living things are made of one or more cells that carry out essential life processes.

taxonomy

The branch of biology that names, classifies, and organizes species into hierarchical categories.

domains

The highest level of taxonomic classification, above kingdoms

domain bacteria

Single-celled, prokaryotic organisms found in nearly every environment on Earth.

domain archaea

Single-celled, prokaryotic organisms that thrive in extreme conditions such as hot springs or salt lakes.

domain eukarya

Domain containing all organisms with eukaryotic (complex) cells, including plants, animals, fungi, and protists.

protist

Mostly unicellular eukaryotes that can function as producers, consumers, or decomposers in ecosystems.

plantae

Kingdom of multicellular organisms that produce their own food through photosynthesis.

fungi

Kingdom of mainly multicellular organisms that decompose organic material and often form symbiotic relationships with plants.

animalia

Kingdom of multicellular organisms that obtain energy by consuming other organisms.

emergent properties

New characteristics that arise at each level of biological organization due to the interaction and arrangement of parts; these properties are not present at lower levels

biosphere

all life on Earth and the places where life exists

ecosystem

all organisms in a particular area and the physical components that life interacts with

community

all organisms in an ecosystem

population

all individuals of a particular species living in a community

organism

an individual living thing

organs and organ systems

body parts that perform specific functions

tissue

group of similar cells performing a specific function

cell

structural and functional unit of life

organelle

membrane-enclosed functional structure in a cell

molecule

chemical structure consisting of 2+ units/atoms

science

An approach to understanding the natural world based on verifiable evidence and systematic observation.

data

Recorded observations used as evidence in scientific study; can be qualitative or quantitative.

qualitative data

Descriptive observations that capture qualities or characteristics (e.g., color, texture, behaviour).

quantitative data

Numerical measurements or counts (e.g., temperature, length, frequency).

hypothesis

a proposed explanation for a set of observations that can be tested through further observation or experimentation but cannot be proven true

experiment

A controlled test designed to investigate a hypothesis by manipulating variables and recording results.

prediction

A statement that describes what is expected to happen in an experiment or observation if the hypothesis is correct.

scientific consensus

The collective agreement among scientists about a hypothesis or theory that is strongly supported by evidence and has withstood repeated testing.

scientific theory

A broad, well-supported explanation for a wide range of observations that generates new hypotheses and is backed by extensive evidence.

variables

Factors or conditions that can change or vary in an experiment.

independent variable

The factor that is manipulated by the researcher to test its effect.

dependent variable

The factor that is measured to determine the outcome of the experiment; it changes in response to the independent variable.

controlled experiment

An experiment in which the researcher manipulates only one variable while keeping all other conditions the same, comparing an experimental group to a control group.

clinical trial

A controlled experiment involving human participants to test medical treatments or interventions.

placebo

A harmless, inactive substance or treatment given to a control group in place of the real treatment to measure the psychological or physiological effect of simply receiving treatment.

double-blind trial

A study in which neither the participants nor the researchers know who receives the real treatment or the placebo, reducing bias in results.

retrospective study

An observational study that looks backward in time using existing data (e.g., interviews, medical records, death certificates) to identify factors related to an outcome.

prospective study

n observational study in which researchers follow a group (cohort) over time, collecting data to see how certain factors influence future outcomes.

evolution

The process of change that has transformed life on Earth from its earliest forms into the diverse organisms present today.

adaptations

Inherited traits that improve an organism’s ability to survive and reproduce in a specific environment.

descent with modification

The idea that species living today descended from ancestral species that were different from them, accumulating changes over generations.

natural selection

The process by which individuals with advantageous inherited traits are more likely to survive and reproduce than those without those traits.

the tree of life

A diagram that represents the evolutionary relationships among all species, showing how diverse life forms share common ancestors.

artificial selection

The selective breeding of domesticated plants and animals to promote the occurrence of desirable traits in future generations.

genetic engineering

The direct manipulation of an organism’s DNA using biotechnology to alter genes or introduce new ones, producing organisms with specific desired traits.

fossil

Preserved remnant or impression of an organism that lived in the past

casts

Fossils formed when an organism buried in sediment decomposes, leaving a mold that later fills with minerals to create a replica

imprints

Marks or impressions left by organisms in sediment (e.g. footprints, burrows, or coprolites) that reveal behavior and environment

coprolites

Fossilized feces that provide information about diet, digestion, and habitat of ancient organisms

strata

Layers of rock formed as new sediment covers older layers; used to determine relative ages of fossils

paleontologists

Scientist who studies fossils

fossil record

Chronological record of evolution preserved in rock layers over geologic time; incomplete due to missing or destroyed fossils

transitional forms

Provide evidence for the gradual changes that occur over time in species; fossils or organisms that show intermediate states between an ancestral form and that of its descendants

homology

Similarity in characters resulting from a shared ancestry

homologous structures

Structures in different species that are similar because of common ancestry but may have different functions

molecular biology

Study of biological structures, functions, and heredity at the molecular level

homologous genes

Genes in different species that share a sequence similarity due to inheritance from a common ancestor

evolutionary divergence

Process by which two or more species evolve different traits from a common ancestor, leading to increased diversity

vestigial structures

Non-functional remnants of a body part that once served a purpose in an organism's ancestor

pseudogenes

DNA segments resembling functional genes but have lost their ability to code for proteins; considered “genetic fossils”

evolutionary tree

a branching diagram that shows hypotheses about the evolutionary relationships among different groups of organisms. Each branch point represents a common ancestor shared by the species that descend from it.

variation

the differences in characteristics (such as colour, size, or behaviour) among individuals within a population that allow selection to act.

heritability

the ability of a trait to be passed from parent to offspring through genetic transmission.

genetic variation

the diversity in gene frequencies within a population that contributes to differences among individuals and provides the raw material for evolution.

phenotypic variation

the observable differences in physical or biochemical traits among individuals within a population, influenced by both genetic and environmental factors.

mutation

a change in the nucleotide sequence of DNA (or RNA in viruses) that serves as the ultimate source of genetic variation.

population

a group of individuals of the same species that live in the same geographic area and can potentially interbreed.

gene pool

the total collection of all alleles for every gene (locus) in all individuals of a population.

allele

an alternative form of a gene that occupies a specific locus on a chromosome and contributes to genetic variation.

locus (loci)

the specific location or position of a gene on a chromosome.

microevolution

small-scale evolutionary changes within a population’s gene pool from one generation to the next.

dominant

an allele that is expressed in the phenotype when at least one copy is present in the genotype (e.g., AA or Aa).

recessive

an allele that is only expressed in the phenotype when two copies are present (homozygous, e.g., aa).

hardy-weinberg equilibrium

the condition in which allele and genotype frequencies in a population remain constant across generations, meaning no evolution is occurring.

genetic drift

a random change in allele frequencies within a population due to chance events, which has a stronger effect in small populations.

bottleneck effect

a type of genetic drift that occurs when a large population is drastically reduced by a disaster, leaving behind a smaller population with different allele frequencies and lower genetic diversity.

founder effect

a type of genetic drift that occurs when a small group of individuals colonizes a new area, leading to allele frequencies that differ from those of the original population.

gene flow

the transfer of alleles between populations through the movement of individuals or their gametes, which reduces genetic differences between populations.

survival of the fittest

a phrase describing how individuals with traits that enhance survival and reproduction are more likely to pass those traits on to the next generation.

reproductive success

the ability of an organism to survive, reproduce, and contribute fertile offspring to the next generation’s gene pool.

relative fitness

the measure of an individual’s reproductive success compared to others in the population; individuals with higher relative fitness leave more offspring.

directional selection

a type of natural selection that favours one extreme phenotype, causing the population’s overall traits to shift in that direction.

stabilizing selection

a type of natural selection that favours intermediate phenotypes, maintaining the status quo and reducing variation.

disruptive selection

a type of natural selection that favours both extreme phenotypes over intermediate ones, potentially leading to two distinct forms within a population.

sexual selection

a type of natural selection in which individuals with traits that enhance their ability to attract or compete for mates are more likely to reproduce.

secondary sexual characteristics

traits not directly involved in reproduction but that distinguish males and females, such as coloration, size, or ornamentation.

sexual dimorphism

distinct differences in size, coloration, or ornamentation between males and females of the same species.

intrasexual selection

competition among individuals of the same sex (often males) for access to mates, sometimes through combat or displays of dominance.

intersexual selection

mate choice, in which individuals of one sex (typically females) select mates based on certain traits, such as coloration, displays, or songs.

antibiotics

drugs that kill or inhibit the growth of infectious microorganisms, often by interfering with their cellular processes such as cell wall formation or protein synthesis.

MRSA (methicillin-resistant Staphylococcus aureus)

a bacterial strain resistant to methicillin and many other antibiotics, making it difficult to treat and a major public health concern.

speciation

the process by which one species splits into two or more distinct species, resulting in the formation of new species over time.

species

a group of populations whose members can interbreed in nature and produce viable, fertile offspring.

biological species concept

defines a species as a group of populations that can interbreed and produce fertile offspring but are reproductively isolated from other groups.

reproductive isolation

biological barriers that prevent members of different species from interbreeding successfully to produce viable, fertile offspring.

hybrids

offspring produced from the mating of two different species or two genetically distinct populations; they may be viable or sterile.

morphology

the study of the physical form and structure of organisms.