variation and extinction Flashcards
what is tissue culture
this is where a few plant cells are put in a growth medium with hormones and they grow into clones of the parent plant
what is tissue culture used for
- to preserve rare plants that are hard to reproduce naturally
- by plant nurseries to produce lots of stock quickly
what do cutting do
they produce genetically identical copies of each parent plant
pros of cuttings
plants can be produced quickly and cheaply
how do you make animal clones
by using embryo transplants
adult cell cloning
how do embryo transplants work
1) sperm cells are taken from the male animal and egg cells are taken from the female animal
2) the sperm is then used to artificially fertilise an egg cells and the embryo that develops is then split many times to form clones before any cells become specialised
3) these cloned embryos can be implanted into lots of other female animals where they grow into babies which will all be genetically identical to each other
how does adult cell cloning work
1) you take an unfertilised egg cell and remove its nucleus
2) then another nucleus is then removed from an adult body cell and is inserted into the egg cell
3) the egg cell is then stimulated by an electric shock, making it divide
4) when the embryo is a ball of cells its implanted into the womb of an adult female and grows into a genetically identical copy of the original adult body cell as it has the same genetic information
what technique was used for the clone sheep dolly
adult cell cloning
cons of cloning
- it reduces the gene pool, reducing variation making the whole population more prone to being wiped out by a disease as there may not be an allele in the population to give resistance to the disease
- cloned animals may not be as healthy as notmal ones
- may lead to humans being cloned in the future with disabilities
pros of cloning
- could lead to a greater understanding of the development of the embryo and ageing of age-related disorders
- could help preserve endangered species
what are fossils
the remains of organisms from many thousands of years ago
what do fossils show
how much or how little an organism has changed over time
3 ways fossils were formed
1) from the gradual replacement by minerals
2) from casts and impressions
3) from preservation in places where no decay happens
how were fossils formed from GRADUAL REPLACEMENT BY MINERALS
1) things that dont decay easily e.g teeth can last a long time when buried
2) they are eventually replaced by minerals as they decay, forming a rock like substance
3) the surrounding sediment also turns to rock but the fossils stay distinct inside the rock and eventually someone digs them up
how were fossils formed from CASTS AND IMPRESSIONS
1) the fossils that formed when an organism is buried in a soft material e,g clay hardens around it and the organism decays, leaving a cast for itself
2) footprints can be also pressed into these material when soft leaving an impression
how were fossils formed from PRESERVATION IN PLACES WHERE NO DECAY HAPPENS
1) n amber ( a clear yellow stone) and tar pits there is no oxygen or moisture so decay microbes cant survive
2) in glaciers its too cold for decay microbes to work
3) peat bogs are too acidic for decay microbes
why cant hypotheses of the foramtion life be accepted
as there is no evidence to support it since
- many early forms of life were soft bodied and many soft tissue tends to decay away completely so the fossil record is incomplete
- fossils that did form millions of years ago may have been destroyed by geological activity
what are species
a group of similar organisms that can reproduce to give fertile offspring
what is isolation
where populations of a species are separated due to a physical barrier
how does isolation lead to speciation
conditions on either side of the barrier will be different causing the environment to be different on each different, causing different characteristics to be more common in each population due to natural selection
what is speciation
the development of new species
when does speciation occur
when the population of the same species become so different that they can no longer sucessfully interbreed to produce fertile offspring
what causes isolation
natural disasters causes barriers causing some species to geographically isolate
what did Wallace do
he came up with the idea of natural selection and published work on the subject with Darwin in 1858, this then caused Darwin to publish on the origin o species, and Wallace’s observation provided lots of evidence of the theory of evolution by natural selection
what causes antibiotic resistance
mutations in a bacterias DNA
why are antibiotic resistance becoming more common
- as bacteria are so rapid at reproducing so they can evolve quickly
- the overuse and inappropriate use of antibiotics
why is antibiotic resistance an advantage for bacteria
as it allows the bacteria to survive even in a host whos being treated to get rid f the infection and so it lives for longer and reproduces many more times, increases the population size of the antibiotic strain
why is antibiotic resistant a problem for people who become infected with these bacteria
as they arnt immune to the new strain and there is no effective treatment, this means that the infection easily spreads between people
why is it important to finish the full course of antibiotics
to make sure all the bacteria is destroyed, so there are none left to mutate and develop into antibiotic resistant strains
what does the antibiotics do in farming
prevent animals from getting sick but can grow bacteria faster, leading to the development of antibiotic resistance in animals which can spread to humans
how have we tried to fix bacteria strains
by drug companies developing new antibiotics which are effective against the resistant strains, however, the rate of development is slow, which means were unlikely to be able to keep up with the demand for new drugs, plus its very expensive
order of Linnaean system
1) kingdom
2) phylum
3) class
4) order
5) family
6) genus
7) species
what is classification
organising living organisms into groups
what does the Linnaeas system do
groups living things according to their characteristics and the structures that make them up
why was the three domain system created
as Carl Woese found that species were not as closely related than shown in the Linnaeas system
what is the 3 domain system
a system that splits organisms into three large groups called domains:
Archaea
bacteria
eukaryotic
what organism were found in the Archaea
different types of prokaryotic cells usually living in extreme environment
what organism were found in the Bacteria
true bacteria
what organisms were found in the eukaryotic
protists, fungi, plants and animal
how are organisms named
according to their binomial system
what does the first part of the binomial refer to
the genus this gives you the information on the organisms ancestry e.g homo is the genus for homo sapiens
what does the second part of the binomial refer to
the species e.g sapiens is the species for homo sapiens
pros of the binomial system
its used worldwide so that scientist from different countries refer to a particular species by the same name to avoid confusion
what do evolutionary trees show
they show ow different species are related to each other by showing a common ancestor and relationship between species
how do scientists work out revolutionary relationships for living organisms
by using current classification data
how do scientists work out revolutionary relationships for extinct organisms
by using information from fossil records
