3.2 Flashcards
natural selection
explain darwins theory of natural selection
living organisms that reproduce sexually show great variety in characteristics due to mutation
they produce an excess of offspring which increases competition
some organisms gain advantageous characteristics so they are more likely to survive and pass on the advantageous characteristic to offspring and it is likely the ones who don’t have this trait will die out
define evolution
the process by which natural selection acts on variation to bring about adaptations and eventually speciation over long periods of time
define natural selection
the evolution of organisms as a result of variation leading to different phenotypes within a specific environment, the alleles which have advantageous attributes are most likely to be passed on to the next generation
define genotype
the genetic make-up of an organism with respect to a particular feature
define phenotype
physical traits expressed as a result of the interactions of the genotype with the environment
define ecology
the study of the interactions of organisms with each other and the environment they are in
define niche
the role of an organism within the habitat in which it lives
what is anatomical adaptations
adaptation involving the form and structure of an organism
what are physiological adaptations
an adaptation involving the way the body of the organism works
what is the mammalian diving response
diving mammals are suited to be under water for longer periods of time as once they are under water their heart rate drops so blood is pumped around the body less often so oxygen is used slower
their main body muscles also work more efficiently using anaerobic respiration so oxygen can focus on brain and heart
what are behavioral adaptations
an adaptation involving programmed or instinctive behavior making an organism better adapted to survive
what is selection pressure
the pressure exerted by a change in an environment or niche on individuals in a population, changes in selection pressure result in evolution of a species
explain how natural selection occurred in oysters
almost wiped out by Malpeque disease
small number of individuals carried an allele giving them resistance to the disease
the frequency of this gene in the population increased rapidly and the oyster remained the same species but are better adapted
explain how natural selection occurred in peppered moths
originally most moths were cream with black spots and some entirely black but the population of black moths remained low as they were easily visible on the pale trees so the frequency of this allele remained low until the industrial revolution occurred and trees became covered in soot and smoke causing the black butterfly allele to become advantageous so the frequency of the allele in the population increased
what is industrial melanism
the evolution of dark-coloured individuals in a habitat due to pollution
state 2 reasons in which natural selection occurs
survival
attracting a mate
what is directional selection
natural selection showing a change from one dominant phenotype to another in response to a change in the environment
define gene pool
all of the alleles of all of the genes in a population
which bacteria do penicillin target
gram-positive bacteria
what is bacterial resistance
a bacterium which is not effected by an antibiotic
what causes bacteria to be resistant to penicillin
an enzyme called penicillinase splits the penicillin molecule so it no longer works
explain antibiotic resistance
original population contains some rare bacteria with mutation for antibiotic resistance
the antibiotic is taken and the bacteria with the mutation are more likely to survive
the new population contains a higher proportion of resistant bacteria and if the antibiotic is taken again this will continue to occur leaving almost entirely resistant bacteria
state factors which contribute to antibiotic resistance
too widely prescribed
wide-spectrum antibiotic are used even when the infection is uncertain of being a bacteria
people don’t complete their course of antibiotics
antibiotics are widely used in the food chain
hygiene in hospitals
no financial incentives to develop new antibiotics
state ways in which we are overcoming antibiotic resistance
reduce use of antibiotics in patients and in food
better education
prescribing the best antibiotic for the infection to maximize effect
DNA sequencing bacteria to identify new ways of targeting them
developing new antibiotics
define species
a group of closely related organisms that are capable of producing fertile offspring
what is speciation
the formation of a new species
how does speciation occur
isolated populations experience different conditions and natural selection occurs in different directions for the two populations until they are no longer capable of interbreeding to produce a fertile offspring
what is hybridization
the production of offspring as a result of sexual reproduction between individuals from different species
when is hybridisation common
in plants
what is geographical isolation
a physical barrier separates individuals from an original population
what is ecological isolation
two populations inhabit the same region but develop preferences for different parts of the habitat
what is seasonal (temporary) isolation
the timing of flowering or sexual receptiveness in some parts of a population drifts away from the norm of the group leading to two groups reproducing separate months apart
what is behavioral isolation
changes occur in the courtship ritual, display or mating pattern that others may not recognize as potential mates
what is mechanical isolation
a mutation changes the genitalia of animals
what is allopatric speciation
speciation that takes place when populations are physically or geographically separated and there can be no interbreeding or gene flow between the populations
what is an endemic species
a species that evolves in geographical isolation and is only found in one place
what is adaptive radiation
when one species evolves rapidly to form a number of different species which all fill different ecological niches
what are marsupials
mammals that give birth to immature young and protect them in pouches
what are monotremes
primitive mammals that lay eggs
what are placenta mammals
mammals that provide for the developing fetus during gestation through the placenta
what is sympatric speciation
speciation that takes place between populations of a species living in the same place
