B15 Flashcards
what did gregor mendel do
carried out breeding experiments using pea plants in mid 1800s
he counted the number of plants with a particular characteristic and recorded his findings
what did mendel observe about his pea plants
observed clear patterns of inheritance in pea plants
what did mendel find out
found that there are separate units of inheritance that are passed on unchanged
some characteristics are dominant
how did mendel describe the patterns
using mathematical models
what is a monohybrid inheritance
the inheritance of a single characteristics involving pairs of units
what happened after mendel
chromosomes were observed in late 1800s
early 1900s scientists realised mendels units behaved in a similar way and this led to the idea that his units were genes on chromosomes
what is the modern gene theory
that genes code for the production of proteins
how long ago do scientists estimate life began on earth
3 billion years ago
what did jean baptiste lamark do
suggested a theory called the ‘inheritance of acquired characteristics’
what is the theory of inheritance of acquired characteristics
characteristics that develop during an organisms lifetime can be passed on to the next generation
what did charles darwin do
suggested the theory of natural selection after his journey to the galapagos islands
how did darwin come across his theory
he noticed that organisms of a particular species show a wide range of variation for a particular characteristic
also observed that reproduction always gives more offspring than the environment can support
what did darwins theory suggest
small changes in organisms took place over a very long time
those that are best adapted to their environment breed and pass on their characteristics
why were darwins ideas slow to be accepted
the theory challenged the idea that god made all animals and plants that live
many scientists didnt agree because there wasn’t enough evidence
how did darwin try to back his theory
tried to show finches on the galapagos islands could change over time if they lived under different environments
what was Wallaces theory suggested
proposed a theory of evolution by natural selection at the same time as darwin
what was wallace most known for
speciation
what is speciation
the process by which new species form
how did wallace think speciation could occur
geographical isolation
environmental isolation
what is geographical isolation
occurs if an island seperates from the mainland or if a new river separates two areas
what is environmental isolation
organisms of a species in one area may be exposed to different environmental conditions
how do scientists conclude speciation has happened
if the two populations are bought together later and cannot breed with eachother
