Transcript L3 evolution

How do giraffes get long necks?
Evolution
Learning Objective:
In order to be successful in this lesson you must be able to:
Describe and explain the effects of competition on different
populations of organisms
Learning Objective:
Interpret information
Describe Darwin’s theory
Explain why Darwin’s
from evolutionary trees
of evolution by natural
theory was only
to explain how closely
selection and compare
gradually accepted
related
are.
In
to be
successful in this lesson you must
bespecies
able to:
withorder
Lamarck’s
theory.
Theories of evolution
Read through sheet explaining Darwin and Lamarck’s theories of evolution.
Explain each to your learning partner
Tell me.
Natural Selection
Darwins theory is often referred to as Darwin’s
theory of evolution by natural selection
Explain how natural selection occurs. 3 marks
variation (between organisms within species)
allow described example
allow mutation – but not if caused by change in conditions
1
those most suited / fittest survive
1
genes / alleles passed on (to offspring / next generation)
allow mutation passed on
1
Gradual acceptance...
Darwins theory was only gradually accepted
because...
1. The theory challenged that God made all the
animals and plants on earth
2. There was insufficient evidence at the time
to convince most scientists
3. The mechanism of variation and inheritance
was not understood until 50 years after
Darwin’s theory was published.
Apply your knowledge
(i)
The image below shows:
•
Phiomia, an ancestor of elephants
•
a modern African elephant.
Phiomia lived about 35 million years ago.
Phiomia
African elephant
Both Phiomia and the African elephant
reach up into trees to get leaves.
In the 1800s, Darwin and Lamarck had
different theories about how the long
nose of Phiomia evolved into the
trunk of the African elephant.
Use Darwin’s theory of natural
selection to explain how the
elephant’s trunk evolved.
(4 marks)
(ii)
Lamarck’s theory is different from
Darwin’s theory.
Use Lamarck’s theory to explain how the
elephant’s trunk evolved.
(2 marks)
(i) In the 1800s, many scientists
could not decide whether Lamarck’s
theory or Darwin’s theory was the
right one.
Give two reasons why.
(2)
(ii) Before the 1800s, many people
had a different idea to explain where
all the living things on Earth came
from.
What idea was this?
(1)
(
(i)
1
variation (in population) / mutation
longer nosed individuals get more food /
leaves
allow longer nosed individuals more likely
to survive
1
(these) survivors breed (more)
1
pass on genes / alleles / DNA (for long
nose)
allow pass on mutation
1
ii)
Phiomia / ancestor stretched its
nose (during its lifetime) to reach
food / leaves
1
passed on (stretched nose) to offspring
allow offspring inherit (stretched nose)
do not allow ref to genes
1
(i) insufficient evidence / no proof
ignore other theories, eg religion
do not allow no evidence
1
mechanism of inheritance not known
allow genes / DNA not discovered
1
(ii) God made all living things / them
allow creationism
ignore religion
1
Evolutionary trees
In this evolutionary tree, species A and B share
a common ancestor. Species F and G share a
common ancestor, which itself shared a
common ancestor with species E. All seven
species share a common ancestor, probably
from the distant past.
The more closely related the
species, the closer the
branches are
Evolutionary trees
M1.
1
(a)
lemur(s)
(b) gorilla(s)
in either order
1
chimpanzee(s)
accept chimps
1
(c) (i) vegetarian finch
1
(ii) R
1
(iii) mangrove and woodpecker finches
1
(d) (i) tree
1
(ii) hippopotamus and pig
both required, either order
allow hippo
1
(iii) new evidence from fossils
1