CHAPTER 15 Flashcards
What did gregor mendel do
he noticed that characteristics in pea plants were passed down from one generation to the next
why did no one understand mendel’s theory at first
no one knew about chromosomes or genes
when was mendels work finally accepted
16 years after his death
1884
What happened in the late 19th century
behaviour of chromosomes during cell division was observed
what were the three conclusions mendel reached
1 characteristics in plants are determined by hereditary units
2 hereditary units were passed unchanged from parents to offspring
3 hereditary units can be dominant or recessive and there must be two recessive for it to show
what happened in the early 20th century
it was observed that there were striking similarities between chromosomes and mendels units. his unit was discovered to be a gene
what were mendels hereditary units
genes
who were in the rivalling teams studying dna
rosalind franklin and maurice wilkins
james watson and francis crick
what were franklin and wilkins doing
they were looking at the structures of dna using x rays
what were crick and watson doing
they were trying to build a 3d model of dna to explain how it works
how was the double helix model of dna discovered
watson and crick used franklins picture
what is lamarcks theory of evolution
the more an organism uses a certain feature the more it develops and grows
these useful characteristics are then passed onto the animals children
what was the main problem with lamarcks idea
his experiments didn’t support his hypothesis -
what is the accepted theory of evolution
all of todays species evolved from simple life forms that started to develop 3 billion years ago
what impact did the south american rheas have on darwin
there were two different types of bird in two different environments - this would support natural selection
under the linnean system of classification what was the largest group
a kingdom
what did carl woese do
proposed the idea of the 3-domain system
how were the new models of classification developed
knowledge and understanding of biochemical processes and microscopes improved
what were the three domains in woese’s system
archaea
bacteria
eukaryota
what are archaea
primitive forms of bacteria
example of archaea
extremophiles
how many kingdoms are in the archaea domain and what are they
1 archaebacteria
example of bacteria
ecoli
how many kingdoms are in the bacteria domain and what are they
eubacteria 1
what are eukaryota
organisms with nuclei that contain genetic material
example of eukaryota
animals
how many kingdoms are in the eukaryota domain and what are they
protista
fungi
plants
animals
what are evolutionary trees
a diagram showing how species are related to each other
how are evolutionary trees for living animals created
by looking at dna
how are evolutionary trees for extinct animals created
by using fossil records
what is classification
the grouping of organisms to their similarities
what did carl linnaeus propose
a classification system where organisms were grouped according to their characteristics
what were the 7 groups linnaeus created
kingdom phylum class order family group species
what is a species
a group of organisms that can breed to produce fertile offspring
under what system are organisms named
the bi-nomial system
who proposed the bi-nomial system
Linnaeus
what language is the bi-nomial naming system in
latin
what are three rules for writing scientific names q
the first name is the genus and is written with a capital letter
the second name is the species and is written without a capital
the name is underlined when hand written or in italics when printed
why were new models of classification proposed
improvements in understanding and knowledge of biochemical processes improvements in microscopes
how do bacteria become antibiotics resistant
they develop a mutation which allows them to survive breed and pass on the resistant allele leading to a whole species becoming resistant
what is a superbug
a bacteria strain that is resistant to most known antibiotics
example of a superbug
MRSA
3 ways to prevent more strains of resistant bacteria being created
not using antibiotics
patients must Finnish their whole course of antibiotics
the agricultural use of antibiotics is being restricted
why is it important to finish the whole course of antibiotics
To ensure all bacteria are destroyed so none are left to mutate and become resistant
why do antibiotics do to contribute to antibiotic resistance
they created a situation where the competitors have been killed so these bacteria have an advantage and increase in numbers
examples of hygiene to stop spreading bacteria 3
medical stage wash hands regularly
infected invidivuals should be isolated
visitors should wash hands thoroughly
problems with the development of new antibiotics
progress is slow and expensive
what is the main cause of extinction throughout history
changes to the environment and climate
how can we tell when there have been mass extinction
fossil evidence - huge numbers of species will disappear
when was the most recent mass extinction and what happened
65 million years ago, dinosaurs became extinct
what is the main idea of what caused extinction of dinosaurs
a giant asteroid hitting earth
evidence to support the idea of an asteroid killing dinosaurs 3
huge crater in mexico
lots of iridium found - only when asteroid strikes there is a layer of rock created by crater debris across the world q
why would an asteroid kill the dinosaurs
huge fires, eruptions spurt gas into atmosphere this made everywhere dark drop in temperature = global winter plants died dinosaurs died
why is the fossil record very limited
only small bits of bones have been found for some species
what is extinction
the permanent loss of all members of a species
how will a species become extinct
as conditions change new species evolve and survive
the old unadapted species will eventually die out
how can a new predator cause mass extinction
if a species cant evolve quickly enough and the predator is powerful it will eradicate a species
5 reasons for extinction
the environment changes to quickly a new predator a new disease competition from another species a catastrophic event
what is a fosil
remnants of organisms from long ago that are found in rocks or ice
what are the three ways in which fossils are created
gradual
replacement by minerals
casts and impressions preservation
how do fossils form by replacement by minerals q
body parts that dont decay easily
eg bones and teeth will last a long time
eventually they will be replaced by minerals
these minerals are shaped like the original part
how do fossils form by casts and impressions
an organism is buried in a soft material
eg clay
the clay will later harden the organism decays
a cast is left
why do fossils form in glaciers
its too cold for the decay causing microbes to operate
why do fossil form in amber
there is no oxygen or moisture so decay causing ,microbes dying
why do fossils form in peat bogs
too acidic for the decay microbes
how is a fossil discovered
the organism dies and is buried in layers of rock
the skeleton becomes mineralised and turns into rock
the rock shift inside the earth whilst still holding the fossil
due to erosion it is gradually exposed
why is the record incomplete 3
many of the earliest forms of life were soft bodied ,
meaning they would leave little fossil evidence behind most organisms didn’t fossilise
there are many fossils still to be found
what is the most common way in which populations of a species become isolated
geographical isolation
examples of geographical isolation 3
a new mountain range
a new river
formation of an island
what is environmental isolation
where the climate that one organism lives in will change but it won’t elsewhere
what is speciation
the development of a new species
how do you know when speciation has occurred
the offspring of interbreeding are infertile
process of speciation
populations are isolated by a barrier conditions on either side of the barrier will be different
each population shows genetic variation
different alleles will be successful - different natural selection
these organisms will be successful and pass on these alleles
characteristics will become more common
why did darwin panic after receiving news from wallace
their ideas were similar and he didn’t want to lose credit
which scientist suggested speciation
walace
what characteristics of animals was the main piece of evidence to support wallaces theory
the warning colours used by animals to deter predators are a successful characteristics developed by natural selection
how did darwin gather evidence to support his ideas 3
he analysed animals and plants he had seen on the different islands to show variation
he bred pigeons to show how characteristics could be inherited
he built up a network of supporting fellow scientists
how have new discoveries helped support darwins theory
we know that phenotypic variations are caused by genetic variations caused by mutations
these beneficial variations are passed on to offspring via natural selection
what is the idea of survival of the fittest
the organisms with the most suitable characteristics for the environment would be more successful competitors and so more likely to survive
3 reasons why people disagreed with darwins theory
it went against religious beliefs
there wasn’t enough evidence to convince scientists
he couldnt explain how variation and inheritance happened
how did the finches of the galapagos islands support darwins ideas
there were similarities between them all but each species was specially adapted to their habitat
what were darwins 3 main ideas
the individuals in a species show a wide range of variation for a characteristic
the environment cant support too many offspring too the fittest and best adapted will survive
these successful organisms will pass on the characteristics that made them survive
