Variation and classification Flashcards
species
group of organisms that are capable of breeding to produce fertile offspring
every organism in a species has the same…
anatomy, physiology, morphology and behaviour
classification
the process of sorting living organisms into groups, organisms within a group share similar features
why do scientists classify organisms?
-to identify species
-to predict characteristics
-to find or show evolutionary links
what are the levels in the system used to classify organisms?
-kingdom
-phylum
-class
-order
-family
-genus
-species
what happens as you move down the hierarchy?
the organisms share more characteristics but there are fewer in each group
what is the smallest unit of classification and why?
species as each group only contains one type of organism
what are the two types of classification?
-artificial classification
-natural classification
describe artificial classification
-groups organisms together based on observable characteristics
why can artificial classification lead to difficulties?
variation within a species can causes difficulties as there may be observable characteristics e.g. dogs look very different but are all the same species
describe natural classification
-organisms are grouped based on a common ancestor
-species may look different but be closely related e.g. the closest living relatives of the elephant are the manatee
how does natural classification work?
-through DNA sequencing scientists can find links between organisms by looking at their evolutionary relationships
what is phylogeny?
the study of evolutionary links
how are phylogenetic links established?
by studying the similarities and differences in DNA between species, the more similar the DNA the more closely related the species
what do phylogenetic trees show?
the evolutionary links between species
speciation events
when a group within a species separates from other members of its species and develops its own unique characteristics- shown by a split in branches
common ancestor
at the point the branches meet, branches that do not reach modern day show species that are extinct
what’s the scientific name for lion?
panthera leo
what’s the genus of a lion?
panthera
what’s the species of a lion?
leo
how do you know the genus of an organism?
the first word in its scientific name
how do you know the species of an organism?
the second word of the scientific name
genome
all of the genetic material of an organism
chromosome
strand of DNA containing genes
karyotype
the number and appearance of all of the chromosomes in a cells nucleus
meiosis
cell division to produce haploid cells
haploid
cells which contain one set of chromosomes
diploid
cells which contain two sets of chromosomes
allele
different versions of the same genes
mitosis
cell division to produce genetically identical diploid cells
phenotype
characteristics that are observed in an organism
gamete
sex cell
gene
section of DNA that codes for a characteristic (protein)
codon
three bases on a strand of mRNA are given this name
homozygous
organisms who have 2 copies of the same allele
heterozygous
organisms who have different alleles for a single parent
dominant
version of a gene whose characteristics are always expressed
recessie
versions of a gene whose characteristic is always expressed is 2 versions are present
evolution
gradual change of species over time
natural selection
the process by which organisms are best suited to their environment survive and reproduce, passing on those alleles
