IB Biology SL

Evolution

change in the inherited characteristics of a population

Selective Breeding

humans decide the favourable variations in organisms and use these organisms as the next generation of parents

Molecular Phylogeny

the comparative analysis of sequences of nucleotide bases and amino acids in proteins

Molecular Clock

measures time from changes in the DNA

Homologous Structures

same basic structure indicating a common ancestry through a common evolutionary organ; indicates divergent evolution

Divergent Evolution

when organisms from the same ancestor adapt to different environmental conditions according to the pressures of natural selection

Analogous Structures

body parts with the same function but different structures; indicate convergent evolution

Convergent Evolution

when distantly related groups of organisms face similar environmental conditions and adapt similarly

Speciation

the process by which new species arise

Reproductive Isolation

barriers that prevent populations of the same species from interbreeding/producing fertile offspring

Differential Selection

measure of the association between a trait value and its ability to confer reproductive success or increase survival rates

Variation

differences between individuals

Evolutionary Fitness

ability to survive and reproduce

Biodiversity

the diversity of life on Earth

Genetic Variation

differences in the genomes among individuals of the same species; prerequisite for natural selection

Mutations

errors in copying the genetic information during DNA replication, resulting in alleles

Selection Pressures

factors that lead to differential survival or reproduction, changing the genetic composition of a population

Density-Dependent Factors

factors that affect population size based on population density

Density-Independent Factors

factors that affect population size irrespective of population density

Biological Fitness

ability of an organism to reproduce and pass on its genetic material to its offspring

Intraspecific Competition

when individuals of the same species compete for limited resources

Sexual Selection

natural selection where the focus is on finding a mate and reproducing

Intrasexual Selection

competition between individuals of one sex to mate with the opposite sex

Intersexual Selection

individuals of one sex choosing an individual of the opposite sex as a mate

Karyotyping

isolating condensed chromosomes taken from cells in mitosis allowing for the comparison of chromosomes between two individuals

Genome

genetic information of an organism

Genome Sequencing

process of determining the order of the bases in an organism's genetic code

Genetic Diversity

variation that exists in the genes of a population

Species Diversity

variety of species seen in a particular habitat

Species Richness

number of different species in an area

Species Evenness

Relative abundance of different species in a given area

Ecosystem Diversity

variety of ecosystems in a given geographical area

Ecosystem

community of organisms and the abiotic environment

Habitat

place where an organism lives and interacts with its surroundings; location that provides the necessary resources for an organism's survival and reproduction

Adaptation

genetic change that increases an organism's chances of survival and reproduction in a particular environment

Sand Dunes

accumulation of sand that has been carried inland from the beach by onshore winds and trapped by debris or plants

Halophytes

plants that can survive high salinity levels

Species Distribution Range

the geographic location and range of occurrence of a particular species

Range of Tolerance

range of environmental conditions within which an organism can optimally survive and function

Transect Line Method

technique to gather data on the distribution and abundance of species in a particular area

Belt Transect

placing a long narrow belt over the area of interest and counting the number of individuals within the belt

Observational Transect

observe and record data along a linear path/transect in a habitat

Line Intercept

recording the points where a line intersects with foliage or stems

Sensors

machines that measure physical or chemical properties

Biome

community of species that occupy a distinct geographical region and are adapted to its environmental conditions; groups of ecosystems that share similar abiotic conditions

Desert

arid regions with little rainfall

- extreme dryness

- high temperatures

- lack of water and vegetation

Rainforest

tropical areas near the equator

- high rainfall

- warm temperatures year round

- moist and humid environment

Specialist Species

limited region in which a species lives with a narrow set of conditions

Generalist Species

broader range of environments in which a species can survive

Ecological Niche

where an organism lives and its role and impacts on the ecosystem

Obligate Anaerobe

cannot survive in oxygen and will respire when there is no oxygen

Facultative Anaerobe

can make ATP when oxygen is present and fermentation if oxygen is absent

Obligate Aerobe

requires oxygen as a final electron acceptor in order to carry out respiration and release energy

Archaea

unicellular and have no true nucleus but are different from bacteria

Hominins

modern and extinct humans and their immediate ancestors

Hominids

hominins and great apes

Herbivores

animals that only eat plant material

Fundamental Niche

ecosystem in which an organism can live and reproduce

Realized Niche

where the organism is best adapted and can live and reproduce

Competitive Exclusion Principial/Gause's Law

it's impossible for two species to occupy the same niche for a long period of time as one will outcompete the other

Niche Partitioning

natural selection permits competing species to occult close areas or niches

Spacial Partitioning

species differ in where they acquire resources

Temporal Partitioning

species have evolved to cope with existing in the same habitat

Population

a group of organisms of the same species that interbreed, sharing a common gene pool

Random Sampling

the unbiased selection of organisms where they each have an equal chance of being chosen

Quadrat Sampling

used to study populations of sessile organisms

Chi-Squared Test

statistical analysis used to determine whether there is a significant association between two categorical variables

Carrying Capacity

maximum population size that a given environment can sustain over a certain period

Population Density

how closely packed individuals are within a given space

Negative Feedback

regulatory mechanisms that counteract or reverse a biological system change, helping maintain homeostasis and equilibrium

Intraspecific Relationships

occur among individuals of the same species

Intraspecific Cooperation

when individuals collaborate to increase their chances of survival and reproduction

Communities

populations within a specific area

Interspecific Interactions

relationships that occur between different species within an ecosystem

Symbiotic Relationships

associations between different species in an ecosystem where they have close and long-lasting connections, resulting in coevolution and adaptation

Herbivory

feeding relationship in which a herbivore consumes plant material as its primary source of nutrients

Predation

predator captures and consumes its prey

Interspecific Competition

when different species compete for limited resources in an ecosystems

Parasitism

symbiotic interaction in which the parasite benefits at the expense of its host

Pathogens

microorganisms capable of causing disease in its host

Mutualism

symbiotic interaction between species where both parties obtain benefits from the relationship

Invasive Species

any organism that is introduced to an ecosystem outside of its native range, potentially causing harm

Population Control

regulation of the size and growth of populations in an ecosystem, helping maintain ecological balance and preventing detriment effects

Top-Down Control

when the abundance or behaviour at lower trophic levels is regulated by the presence and activities at higher trophic levels

Bottom-Up Control

when the availability of resources at lower trophic levels influences the abundance and distribution of organisms at higher trophic levels

Allelopaths

organisms that release chemical substances into their environment to deter potential competitors

Matter

nutrients, gases and substances essential for the functioning of living organisms

Energy

ability to perform work or cause change required for biological processes

Open System

allows energy and matter to be exchanged with its surroundings allowing for continuous inputs and outputs of energy and matter

Closed System

exchange of energy with the surrounding environment but restricts the flow of matter

Isolated System

neither energy nor matter are exchanged (ideal)

Decomposers

break down dead organisms and organic matter by extracting energy and nutrients from decaying materials

Decomposition

the breaking down of complex organic substances in the environment

Saprotrophs

decomposers that obtain nutrients with external digestion

Detritivores

decomposers that obtain nutrients with internal digestion

Heterotrophs

consumers that cannot produce their own organic molecules and rely on consuming other organisms or organic matter to obtain energy and nutrients

External Digestion

release of hydrolytic enzymes into the surrounding environment to break down complex organisms

Internal Digestion

ingestion of food, digestion within specialized organs and absorption thhat transports smaller molecules to the cells for assimilation

Mixotrophs

organisms that acquire nutrients through autotrophic and heterotrophic means

Cell Respiration

oxidation of carbon compounds so organisms can extract energy from organic molecules and convert it to ATP