Evolution Flashcards
How long ago was the big bang?
13.7 billion years
How long ago was the sun formed?
5.6 billion years ago
How long ago was the Earth formed?
4.6 billion years ago
How long ago was the first life?
3.6 billion years ago
Can we know for sure how and when life on Earth began? Why?
no
no-one was there to observe it
we cannot do experiments to repeat the origin of life
What was Lamarck’s theory?
The inheritance of aquired characteristics
What does Lamarck’s theory say?
characteristics of individuals change during their own lifetime
the changed (aquired) characteristics are passed on to the next generation
Use the example of long necks for giraffes to explain Lamarck’s theory
giraffes used to have short necks, but they preffered to eat leaves from high trees
as they reached for high trees their necks became longer
the long neck characteristic was passed on to offspring
What are the pros of Lamarck’s theory?
changes in individuals can be aquired over time
What are the cons of Lamarck’s theory?
aquired characteristics are not passed on
What was Darwin’s theory?
Theory of evolution by natural selection
What was Darwin’s observations on finches?
there is a lot of variation between species
different islands have different food sources
different beaks suit different food sources
What were Darwin’s conclusions?
finches show variation in beak size and shape
finches with long, thin beaks are better adapted to catch insects living between rocks, compared to finches with wide, short breaks
finches with long, thin beaks are more likely to survive and breed while less well adapted finches may die before reproducing
the characteristics of the finches with long, thin beaks are passed on to the offspring
over time the number of finches with long, thin beaks increases, while the number of finches with short, wide beaks decreases
What is natural selection
mechanism for evolution
explains how some characteristics become more common
What does natural selection show about selection pressures?
selection pressures exist in environment (e.g. food source)
this leads to selection (survival) of those organisms that are best suited to this particular environment
these survive and pass on their genes (while others don’t)
characteristics of these organisms become more common
What are some examples of selection pressures?
predators
food
disease
climate
finding a mate
where does variation come from?
random mutations in genes
not forced by the environment
variation exists before selective pressures (but can be useful later)
Complete this beetle example diagram
what are peppered moths?
there are dark and light forms of the peppered moth
moths rest on tree bark during the day
before the industrial revolution what was the case with tree bark and peppered moths?
tree bark was covered with lichen (makes bark pale)
predomincance of light forms of moth in UK
after the industrial revolution what was the case with tree bark and peppered moths?
dark forms in polluted areas (light forms in rural areas)
Complete this table about peppered moths
Complete this table about antibiotic resistant bacteria
Complete this table about sickle cell anaemia
why is it better to be a carrier of sickle cell anaemia in regions with malaria than not to be?
if you are a carrier then you cannot have sickle cell anaemia
thus you are protected
what is the definition of Darwin’s Theory of Evolution?
all species of living things have evolved from simple life-forms which first developed more than three billion years ago through the process of natural selection
what is the variation, selection pressure and organisms selected for for rabbits with very long ears in the desert?
variation = different ear length
selection = hot temperature
organisms selected for = long ears - larger SA/V ratio, easier to lose heat
what is the variation, selection pressure and organisms selected for stick insects?
variation = different colours/shape of insect
selection pressure = predators
organisms selected for = good camouflage - harder for predator to find them
what is the variation, selection pressure and organisms selected for giraffes having long necks?
variation = different neck length
selection pressure = food - high up and mates
organisms selected for = long necks -able to reach food, attractive
what is the variation, selection pressure and organisms selected for cacti having spines instead of leaves?
variation = different sized spines/ leaves
selection pressure = heat (water loss), herbivores
organisms selected for = smaller SA and least water is lost, protection from predators
what is the variation, selection pressure and organisms selected for peacocks having brighlty coloured feathers?
variation = different feather colours
selection pressure = finding a mate (sexual selection)
organisms selected for = most brightly coloured feathers - most attractive
what is a fossil?
mineralised or otherwise preserved remians of organisms
what two categories of fossils are there?
body fossils
trace fossils
what is a body fossil?
fossilised remains of an organism
what are some examples (9) of body fossils?
bones
claws
teeth
eggs
embryos
skin
muscles
tendons
organs
what is a trace fossil?
fossilised record of the activity of an organism
what are some examples (6) of a trace fossil?
trackways (set of footprints)
toothmarks
gastroliths (stones swallowed and used for digestion to grind food)
coprolites (fossilised faeces)
burrows
nests
what are the types (3) of fossils?
mold fossils
cast fossils
true form fossils
what is a mold fossil?
fossilised impression (negative image)
what is a cast fossil?
formed when mold fills in
what is a true form fossil?
fossil of actual organism
what are the types (6) of formation of fossils?
unaltered preservation
permineralisation = petrification
replacement
carbonisation = coalification
recrystallisation
authigenic preservation
what is unaltered preservation?
insects or plant parts trapped in amber, a hardened form of tree sap
what is permineralisation?
= petrification
rock-like minerals seep in slowly and replace the original organis tissue with silica, calcite or pyrite, forming rock-like fossil
what is replacement?
an organism’s hard parts dissolve and are replaced by other minerals, like calcite, silica, pyrite or iron
what is carbonisation?
= coalification
in which only the carbon remains in the specimen - other elements, like oxygen and nitrogen are removed
what is recrystallisation?
hard parts either revert to more stable minerals or small crystals turn into larger ones
what is authigenic preservation?
molds and casts of organisms that have been destroyed or dissolved
what can fossils tell us (3)?
when animals presumbly lived
how much or how little species have changed over time
what sorts of organisms existed that are no longer around
what can’t fossils tell us (2)?
what organisms looked like exactly
if organisms are really derived from one another
what is extinction?
the permanent loss of all the members of a species from earth
what is mass extinction?
loss of a number of species at the same time
what are some examples (4) of mass extinction?
environmental change - climate change (e.g. the Ice Age), meteorites, vocanoes
new predators
new diseases
competition
what is this type of formation of fossils is this?
insects or plant parts trapped in amber, a hardened form of tree sap
unaltered preservation
what is this type of formation of fossils is this?
= petrification
rock-like minerals seep in slowly and replace the original organis tissue with silica, calcite or pyrite, forming rock-like fossil
permineralisation
what is this type of formation of fossils is this?
an organism’s hard parts dissolve and are replaced by other minerals, like calcite, silica, pyrite or iron
replacement
what is this type of formation of fossils is this?
= coalification
in which only the carbon remains in the specimen - other elements, like oxygen and nitrogen are removed
carbonisation
what is this type of formation of fossils is this?
hard parts either revert to more stable minerals or small crystals turn into larger ones
recrystallisation
what is this type of formation of fossils is this?
molds and casts of organisms that have been destroyed or dissolved
authigenic preservation
Complete this gap fill:
One important piece of … for how life has developed on eath is …. The most common type are formed when parts of the … or … are replaced by … as they decay over long periods of time. Some … were formed when an organisms did not … after it died. … are rare.
One important piece of evidence for how life has developed on eath is fossils. The most common type are formed when parts of the plant or animals are replaced by minerals as they decay over long periods of time. Some fossils were formed when an organisms did not decay after it died. Ice fossils are rare.
Complete this gap fill:
The theory of evolution states that all the … which are alive today - and many more which are now extinct … from simple life forms, which first developed more than three … years ago. Darwin’s theory of evolution takes place through … selection. Studying the similarities and differenced between species helps us to understand how they have evolved and how closely … they are to each other. When a … has a good effect it produced an … which makes an … better suited to its …. This makes it more likely to … and …. The … then gets passed on to the next …. This is ….
The theory of evolution states that all the species which are alive today - and many more which are now extinct evolved from simple life forms, which first developed more than three billion years ago. Darwin’s theory of evolution takes place through natural selection. Studying the similarities and differenced between species helps us to understand how they have evolved and how closely related they are to each other. When a mutation has a good effect it produced an adaptation which makes an organism better suited to its environment. This makes it more likely to survive and reproduce. The mutation then gets passed on to the next generation. This is natural selection.
Complete this gap fill:
… is the permanent loss of all the members of a … from the …. It may be caused by changes in the … or …, to new …, new … or possibly new …
Extinction is the permanent loss of all the members of a species from the earth. It may be caused by changes in the environment or climate, to new predators, new disease or possibly new competitors
what is selective breeding?
breeding only those individuals with desired characteristics (artificial insemination)
what are some desired characteristics (8) for plants?
high yield
disease resistant
pesticide resistant
hardier (survive in harsh climates)
good nutrient balance in crops
high growth rate
flavour
looks (e.g. flower)
what are some desired characteristics (7) for animals?
more meat, milk, eggs
more fur/better quality fur
more offspring
disease resistant
soeed (e.g. race horse)
looks (e.g. dogs)
character (e.g. dogs)
How does selective breeding work in milk cows?
there is natural variation in milk cows
select high yield milk cow
mate with bull from high yield milk cow family (artificial insemination)
select high yield offspring and repeat process
what is the selection pressure in natural selection vs artificial selection (selective breeding)?
natural selection = disease, climate, predators
artificial selection = human choice
who survies the selection pressure in natural selection vs artificial selection (selective breeding)?
natural selection = only organisms with favourable traits survive and breed
artificial selection = only organisms with desired traits are chosen to breed
what is the selection pressure of wheat?
high yield
high resistance
what is a modern breeding technique?
cloning
what is cloning?
any method that produces genetically identical offspring
what two ways can you clone plants?
cutting
micropropagation
how do you clone plants through cuttings?
take a small piece of plant and grow it in the right conditions
how do you clone plants through micropropagation?
take a few cells/ or small parts from the plant (= explants)
put them into culture medium
let them grow into many new plants
what way can you clone animals?
reproductive cloning
how do you clone animals through reproductive cloning?
transfer a nucleus from a somatic cell of donar A to an empty egg cell from B to form a diploid zygote with A’s DNA
the developing embryo is implanted into the uterus of a foster mother (C) to develop and give rise to a clone of A
what is the natural variation (due to chance mutation) in sickle cell anaemia in malaria-free regions (e.g. Europe) vs regions with malaria (e.g. Africa)
malaria-free regions = sickle cell haemoglobin + normal haemoglobin
malaria = sickle cell haemoglobin + normal haemoglobin
what is the selection pressure in sickle cell anaemia in malaria-free regions (e.g. Europe) vs regions with malaria (e.g. Africa)
malaria-free regions = oxygen transport
malaria = oxygen transport + malaria
which type has the selective advantage in sickle cell anaemia in malarie-free regions (e.g. Europe) vs regions with malaria (e.g. Africa)
malarie-free = HnHn
malaria = HnHs
(H = haemoglobin, N = normal, S = sickle)
which type is selected for in sickle cell anaemia in malarie-free regions (e.g. Europe) vs regions with malaria (e.g. Africa)
malaria-free = HnHn
malaria = HnHs
(H = haemoglobin, N = normal, S = sickle)
which type is selected against in sickle cell anaemia in malarie-free regions (e.g. Europe) vs regions with malaria (e.g. Africa)
malaria-free = HsHs, HnHs
malaria = HsHs, HnHn
what is the result over generations in sickle cell anaemia in malarie-free regions (e.g. Europe) vs regions with malaria (e.g. Africa)
malaria-free = sickle cell anaemia-free
malaria = sickle cell anaemia still present
Why do people in regions with malaria want one HnHs?
they will survive and cannot catch malaria
HsHs = dies of malaria
HnHn = can catch malaria and die
Describe what is meant by a mutation and explain the effect a mutation could have in a population of organisms
mutation = change/damage/ mistake to genetic material
passed on
rare/random
alters characteristics (e.g. sickle cell)
increase/decrease of gene/allele/ numbers in population
natural selection/evolutio
must give examples of advantages/disadvantages and characteristics
describe the process of selective breeding
humans/farmers select organisms
desired features/characteristics chosen
mate/reproduce/cross/artificial insemination
repeat/several generations/ select offspring
give one example of two desired characteristics developed by selective breeding in a named crop plant
desired characteristic = high yield / short stem
crop plant = wheat
give two ways in which natural selection differs from selective breeding
- the selection pressure of selective breeding is human choice whereas in natural selection it is factors such as disease or predators
- in artificial selecion, only organisms with desired traits are chosen to breed whereas in natural selection only organisms with favourable traits survive and breed
