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84 terms

IB Biology Review

Review of all IB Biology subjects.
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ecology
the study of relationships between living organisms and between organisms and their environment
ecosystem
a system made up of organisms as well as the abiotic factors in the area
population
a group of organisms of the same species who live in the same area at the same time
community
a group of populations living and interacting with each other in an area
species
a group of organisms which can interbreed and produce fertile offspring
habitat
the environment in which a species normally lives or the location of a living organism
autotrophs
producers; they can make their own food
heterotrophs
consumers; they feed on ready made organic material
detritivores
organisms that feed on the detritus and decomposing organic material of living organisms
saprotrophs
decomposers; organisms that feed on dead organisms and products of living organisms
carrying capacity
the maximum number of organisms of a species, or the maximum population size which an environment is able to support
random sample
a sample where every individual in a population has an equal chance of being chosen
trophic level
Position in the food chain, determined by the number of energy-transfer steps to that level; a functional classification of taxa within a community that is based on feeding relationships
standard deviation
used to summarize the spread of values around the mean; ∑((X-X)²/n-1)
species
a group of organisms with similar characteristics, which can interbreed and produce fertile offspring
protoctista
unicellular and multicellular eukaryotic organisms; may be auto or heterotrophic and live in salt and fresh water
fungi
eukaryotic and feed by absorption of nutrients; cell walls are made of chitin
plantae
eukaryotic photosynthetic organisms; cell wall contains cellulose and cells contain chlorophyll
animalia
feed by ingestion
evolution
change in a gene pool of a species over a period of time
half-life
the number of years it takes for 50% of a sample to decay
organelle
a discrete structure within a cell, and has a specific function
magnification
measure size of diagram ÷ actual size of object
tissue
an integrated group of cells that share structure and are adapted to perform a similar function
organ
a combination of two or more tissues which function as an integrated unit, performing one or more specific functions
organ system
a group of organs that specialize in a certain function together
diffusion
movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient
osmosis
passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration across a semi permeable membrane
organic
molecules containing carbon that are found in living systems (Not CO2); often have covalent bonds
enzyme
a globular protein that accelerates a specific reaction; catalysts that can be used over and over
active site
the region of an enzyme surface that binds to the substrate during the reaction catalyzed by the enzyme
denaturation
a structural change in a protein that results in a loss of its biological properties
degenerate
more than one codon can code for a single amino acid
universal
codes are the same for all living organisms
recombination
the reassortment of genes into different combinations from the parents
gene
a heritable factor that controls a specific characteristic consisting of a length of DNA occupying a specific position on a chromosome called a locus
allele
a specific form of a gene, usually differing from other alleles by one or a few bases only and occupying the same locus as other alleles of the gene
genome
the total genetic material of an organelle, organism, or cell
gene pool
the total of all genes carried by the individuals in a population
gene mutation
a change in the base sequence of a gene
genotype
the alleles possessed by an organism
phenotype
the characteristics of an organism
dominant allele
an allele which as the same effect on the pheno type whether it is in a homozygous or heterozygous state
recessive allele
an allele which has an effect on the phenotype in the homozygous state
codominant alleles
alleles which have a partial effect in the heterozygous state but a more pronounced effect in the homozygous state
locus
the position of a gene on the chromosome
homozygous
having two copies of an allele
heterozygous
having different alleles of a gene
carrier
an individual that has a recessive allele that does not have an effect on the phenotype
test cross
testing a suspected heterozygote by crossing it with a known recessive homozygote
sex linkage
genes carried on the sex chromosomes, usually the X
linkage group
a group of genes whose loci are on the same chromosome
polygenic inheritance
the inheritance of a characteristic which is controlled by more than one gene
genetic screening
testing individuals in a population for the presence of a gene (or a certain allele of a gene)
clone
a group of organisms of identical genotype or a group of cells descended from a single parent cell
cell respiration
the controlled release of energy in the form of ATP from organic compounds in cells
pathogens
organisms that cause disease
active immunity
immunity due to production of antibodies by the organism itself after infection
passive immunity
immunity due to acquisition of antibodies from another source (can be injected by needle or passed through placenta or breast milk)
natural immunity
immunity due to infection
artificial immunity
immunity due to a vaccine
resting potential
electrical impulse across a cell membrane when not propagating an impulse
action potential
the localized reversal and then restoration of electrical potential between the inside and outside of a neuron as the impulse passes along it
innate behavior
behavior that normally occurs in all members of a species despite natural variation in environmental influences
taxis
locomotion in a particular direction in response to an external stimulus
kinesis
movement in an organism where the rate depends on the stimulus
classical conditioning
modification of behavior in an animal as a result of the detection of correlations between external events
operant conditioning
a learning procedure in which a reinforcement follows a particular response
imprinting
an attachment to an object encountered during a short period after birth, usually a parent
food chain
a linear and simple feeding relation, where one organism has one type of food and is eaten by one type of organism
food web
more complex than a food chain and it includes a larger variety of organisms, Each of which feed on a variety of other organisms and they are in turn fed on by more organisms
greenhouse effect
a NATURAL PHENOMENON that was required for life to form on the planet
energy flow (in a food chain)
energy losses between trophic levels include material not consumed or material not assimilated and heat loss through cell respiration
population size factors
if (natality + immigration) > (mortality + emigration) then a population is increasing
exponential phase
occurs when there are no controlling factors
transitional phase
the birthrate begins to decrease
plateau phase
occur as carrying capacity is reached
density dependent factors
more effect in crowded populations (predation and disease)
density independent factors
independent of population size (weather, natural disasters)
extrinsic population-regulating mechanisms
originate outside the population (food supply, natural enemies, disease, weather)
intrinsic population-regulating mechanisms
seen in the physiology or behavior (less offspring in crowded populations, mass migration)
kingdoms
prokaryotae, protoctista, fungi, plantae and animalia
prokaryotes
unicellular organisms lacking a nucleus and other membrane-bound organelles; circular DNA
Taxa hierarchy
kingdom, phylum, class, order, family, genus and species