Chapter 14 Flashcards
what are the two types of variation?
environmental and genetic
what cause genetic variation?
the fusion of two sets of DNA - one from mother, one from father
examples of characteristics influenced only by genes (3)
eye colour
inherited diseases
blood group
what causes environmental variation?
the conditions and environment an organism lives and grows in
definition of environmental variation
differences between organisms of the same species due to differences in their surroundings
definition of genetic variation
the combination of two sets of DNA leading to different characteristics in the offspring
examples of characteristics caused by environmental variation 3
suntan
education
height of plants
what are most characteristics caused by?
both environmental and genetic variation
what is natural selection?
the organisms with the most suitable characteristics for an environment survive and pass on these successful alleles
what is a mutation?
a change in the genetic code
what does evolution through natural selection suggest?
only the most well adapted to an environment will survive and pass on their alleles, leading to changes in the characteristics of organisms
4 key steps in natural selection
mutation of gene - advantage of survival - breed - pass on genes
what will a mutation very rarely lead to?
a new phenotype
theory of evolution
all of todayโs species have evolved from simple life forms that started to develop billions of years ago
example of mutation in action
the Malpeque Bay oysters
came down with a disease that killed many of them but a few had a mutation of a disease resistant gene so went on to breed all oysters with this gene
what is the phenotype caused by?
genes
what is speciation?
development of a new species
how does speciation occur?
the phenotype of an organism changes so much that a completely new species is formed
what is extinction?
no individuals of a species remain
3 reasons for extinction
new predator
new disease
catastrophic event