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Science
Stage 5
Evolution
Set 3: Evolution by selection
NEW SOUTH WALES
D E PA R T M E N T
OF EDUCATION
AND TRAINING
Number: 43943
Title: Evolution
This publication is copyright New South Wales Department of Education and Training (DET), however it may contain
material from other sources which is not owned by DET. We would like to acknowledge the following people and
organisations whose material has been used:
Photograph of Tyrannosaurus Rex © Rhonda Caddy
Extracts from Science Syllabus Years 7-10 ©Board of Studies, NSW 2003
Photograph of T-Rex model © Rhonda Caddy
Photograph of fossilised bones, USA © Rhonda Caddy
Photograph of an apatosaurus © Rhonda Caddy
Photograph of a velociraptor © Rhonda Caddy
Photograph of Earth from space © NASA
Photograph of a waratah ©Jane West
Diagram of the tree of life from Messel H (ed) (1963) Science for High School Students,
Nuclear Research Foundation, University of Sydney
Front Cover, Set
Covers and
Set 1 p 14
Introduction pp iii-v
Set 1 p 15
Set 1 pp 16, 41
Set 1 p 19
Set 1 p 20
Set 1 p 41
Set 2 p 8
Set 3 p 4
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© State of New South Wales, Department of Education and Training 2005.
i
Evolution
Here are the names of the lessons in this unit.
Set 1
☞
A history of Earth
Lesson 1
Lesson 2
Lessons 3 and 4
Lesson 5
Thinking about change
So what has happened?
Timeline Earth
A look at dinosaurs
Set 2
Evolutionary theories
Lesson 6 and 7
Different ideas and viewpoints
Lessons 8 and 9
Scientific theories
Lesson 10
Multiple choice questions
Set 3
Evolution by selection
Lesson 11
Darwin’s theory
Lessons 12 and 13
The importance of evidence
Lesson 14
New evidence, new theories
Lesson 15
Selection to extinction
Evolution Set 3
ii
Set 3: Evolution by selection
Contents
What will you learn in Set 3? ...................................................................... iii
What do you need for Set 3? ....................................................................... iv
Lesson 11
Darwin’s theory ........................................................ 1
Lessons 12 and 13
The importance of evidence.................................... 7
Lesson 14
New evidence, new theories................................. 13
Lesson 15
Selection to extinction ............................................ 17
Checking your progress.............................................................................. 27
Suggested answers ...................................................................................... 29
Send-in pages ............................................................................................... 35
Evolution Set 3
iii
What will you learn in Set 3?
In Set 3, you will have opportunities to:
•
evaluate the theories proposed by Cuvier and Lamarck
•
discuss evidence for evolution of life on Earth
•
construct diagrams to explain evolution by natural selection
•
use the theory of natural selection to explain how evolution occurs
•
identify advantages and disadvantages of DNA changing
•
describe how ideas come to be accepted by groups of scientists
•
identify examples where non-scientific ideas have impacted on science
•
extract information from a game
•
discuss how humans can limit their impact on environments.
Evolution Set 3
iv
What do you need for Set 3?
Here is a reminder of the items you need for Set 3. To save time,
it might be a good idea to get all these things ready before you start.
Items marked with a star, *, are optional.
For
Home
Lesson 11
• pencil
• ruler
Lessons
12 and 13
* one or two sheets of paper
Lesson 15
• die (two of these are called dice)
• token, such as a button
• scissors
* toothpick or match
* sticky tape
Evolution Set 3
1
Lesson 11
Darwin’s theory
The theories of evolution that are currently used by scientists are
based on the theory proposed by Charles Darwin.
Who was Charles Darwin?
Darwin (English, 1809–1882) was a
naturalist (a scientist who studies
nature, particularly the structure and
behaviour of organisms). At that time
in history, it was a common thing for
people from wealthy families to collect
and study organisms and rocks.
Darwin became interested in organisms
as a child. He started to study medicine
to become a doctor, like his father.
However, he changed courses to learn
theology (the study of ideas about God).
He could have become a minister of
the Church of England when he
finished his studies in 1831.
Instead, Darwin left England on a ship called the HMS Beagle.
The ship was going to South America and Australia to survey islands
and coastlines, and Darwin went along as an unpaid naturalist.
On this journey, he observed a wide variety of plants and animals.
He saw many similarities and differences but was particularly
impressed by differences between very similar species. He was also
amazed to see organisms that were like fossils he had seen.
When he returned to England, Darwin continued to study and
investigate nature. He observed and checked much of the evidence
that scientists were using (and still use) to show that organisms change
over time. (This is the same evidence that you studied in Set 2,
except that Darwin did not have information about DNA and genes.)
He tried to find a new explanation of how evolution occurred.
Evolution Set 3
2
What was Darwin’s theory?
Darwin observed that there are many different organisms on Earth.
This is called diversity. He also saw that populations of organisms
gradually change over time, or evolve. What explanation did he propose?
Natural variation
Darwin observed that organisms in a population were not all alike.
These differences between individuals are called variations.
For example, here are some variations in a population of prawns.
A
1.
B
C
D
Compare prawn A with the other three prawns. You will be able
to see a lot of similarities. But there are some differences too.
How can you distinguish between prawn A and prawn:
B?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
C?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
D?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Turn to the answer pages and read the instructions for using suggested answers
in this lesson. Then check your answers for Question 1.
Natural selection
Darwin suggested that the differences between organisms meant that
some individuals were more likely to survive and reproduce than others.
He said that these organisms were chosen, or selected, to pass on their
characteristics.
Which ones survived and reproduced depended on the environment;
that is, on nature. So the selection of organisms was done by nature.
Darwin called this process natural selection.
Evolution Set 3
3
Try this example.
2.
Imagine that the four prawns on page 2 live in a dark-coloured lake.
Which one do you think is most likely to be caught by a seagull?
Did you think that the dark-coloured prawns (A, B and C) would be
better able to hide in a dark lake? Prawn D would be easier to see so it
could be easier for a seagull to catch it.
Darwin would explain that the pale-coloured prawns would be eaten.
It would be less likely that they would survive and reproduce.
Gradually over time, there would be fewer and fewer pale-coloured
prawns. Eventually, all the prawns in this dark-coloured lake would
be dark-coloured.
Now imagine another example.
3.
A dark-coloured lake contains a lot of dark weed. Prawns with
short antennae and short legs can swim more quickly through the
weed to escape from fish in the lake. Which prawn do you think
is most likely to survive and reproduce? Explain your answer.
Please check your answer.
4.
Predict the changes that might happen in the population of
prawns in a light-coloured lake with lots of pale weed.
Compare your answer with the ones in the answer pages.
These small changes in a prawn population could occur over a period
of a few years. Darwin proposed that many small changes over the
millions of years that life has been on Earth would lead to large changes.
These large changes would produce organisms that are very different.
Thus, Darwin explained the diversity and evolution of life on Earth.
Evolution Set 3
4
The idea that populations of organisms can gradually change their
features over time is often represented in a diagram. This kind of
diagram can be called a tree of life.
© Harry Messel (ed), 1965 Science for High School Students
The tree of life diagram below illustrates the theory that all living things
have developed from one ancient life form. Gradual change over
millions of years has produced the diversity of life that we are able to
observe in the fossil record and in the world today.
The numbers in the diagram represent the approximate number of species in each group named.
Evolution Set 3
5
Darwin’s theory of evolution by natural selection is sometimes called
the survival of the fittest. Both these phrases – natural selection, and
survival of the fittest – are names given to Darwin’s theory.
Survival of the fittest
What do you think of when you hear the word fittest? It often describes
the person who can run the fastest, or for the longest. But that is not
what Darwin meant.
Darwin described the individual that was best able to survive
and reproduce in its environment as the fittest. It had
characteristics that made it suited, or adapted, to its environment.
It stayed alive, or survived, because it was adapted to its surroundings.
And because it stayed alive, it was more likely to reproduce and
so pass its characteristics on to new individuals in the population.
But survival of the fittest also means that many organisms die
without reproducing. This is what happens in nature. Many offspring
are often produced – sometimes thousands, even millions – yet only
a few survive to be adults and to reproduce themselves.
Review of Darwin’s theory
Here are some tasks for you to try.
5.
Outline what is meant by natural selection.
6.
How does survival of the fittest account for evolution?
Evolution Set 3
6
7.
Draw diagrams to complete this summary of Darwin’s theory.
Many offspring are produced in a population.
Although these individuals are very similar,
they are different from each other.
Individuals that are adapted to their environment
tend to stay alive. Individuals that are less suited
to the environment die or are killed.
Individuals that survive are able to reproduce.
They pass their features, which have helped them
to survive, on to their offspring.
So, there is a gradual change in the features
of individuals in the population.
Please compare your answers with the ones in the answer pages.
Exercise 11
Now complete this send-in exercise about Darwin’s theory.
Evolution Set 3
7
Lessons 12 and 13
The importance of evidence
Evidence is very important in science. It is what scientists collect
to deduce and test their inferences, hypotheses, theories and laws.
You also need to present evidence to support the answers that
you give in science lessons and tests.
Evidence and scientific theories
So far in this unit, you have learned about three different scientific
theories that are based on the same types of evidence. How can you
tell which theory is the best scientific explanation?
Scientists look for more and more evidence. They study evidence from
different areas of science that might test the theory in a different way.
They deduce new theories that are better scientific explanations of
the evidence. (Remember, there are other ways to explain everything,
based on your viewpoint and beliefs. Scientists look for scientific
explanations.)
In this section, you’ll review the evidence for evolution and the
theories of Cuvier, Lamarck and Darwin. You’ll see how evidence
affects which scientific theories are currently accepted.
Using scientific evidence to assess scientific theories
Here is a reminder of the types of evidence available to Cuvier,
Lamarck and Darwin. (Recall that they did not know about DNA
and genes.)
Evolution Set 3
8
The fossil record
Fossils are evidence of organisms that
lived on Earth in the distant past.
Recorded
genetic changes
Selective breeding
by humans has
produced variation
in plants and animals.
Similar variations
have also occurred
naturally.
Structural and chemical
similarities of organisms
Geographical distribution of
related species
Different organisms contain
parts that are alike, such as
the forelimbs of vertebrates.
All organisms are based on
carbon compounds and almost all
pass on genetic information
stored in DNA.
Endemic species develop
when areas are separated
by geographical features.
Organisms tend to be more
different if they come from
areas that are geographically
further apart.
Scientific evidence and Cuvier’s theory
Cuvier’s theory of extinction explained the fossil record. His belief in
the perfection of organisms accounted for the geographical distribution
of organisms and for their structural and chemical similarities.
But Cuvier could not explain how organisms could be changed by
selective breeding. This evidence meant that Cuvier’s theory had to be
either changed or discarded. Scientists decided to look for a better theory.
Scientific evidence and Lamarck’s theory
Lamarck’s theory of acquired features explained all four types
of evidence. However, scientists gradually realised that it could not
be correct. They found evidence that refuted the theory.
Consider this situation.
You have two mice…
and you cut off their tails.
Using Lamarck’s theory, you would predict that these mice would
develop in other ways to make up for their lost tails. They would
learn to do without a tail.
Evolution Set 3
9
Then you mate the tail-less mice so that they reproduce.
Using Lamarck’s theory, you would predict that the offspring would
not have tails because they would inherit the new characteristic of
being tail-less from their parents.
But what are the offspring like?
They all have tails.
Scientists did experiments like this over and over. They tested
different plants and animals. But they could not find evidence that
offspring inherit changes in features that parents have acquired
during their lifetime. Lamarck’s theory had to be replaced.
Interestingly, Lamarck’s theory continued to be the politically and
scientifically accepted theory of evolution in Russia until the 1920s.
Most Russian scientists ‘saw’ evidence to support the theory because
they believed it (or because they would be punished if they did not).
Scientists elsewhere in the world did not observe the same results
because they had a different viewpoint.
Try these tasks using the information provided on page 8 and 9.
(This means that you should use information from page 8 and 9 only.
Do not use any other information, even if you think it is better! In a test,
this direction means that other answers would be marked as wrong.)
1.
Describe how an idea can gain acceptance in the scientific
community as either theory or law.
2.
Political ideas in Russia at the beginning of the 1900s
affected the development of scientific ideas about evolution.
Discuss this idea by:
(a) identifying the political belief about evolution in Russia
at that time
Evolution Set 3
10
(b) justifying the conclusion that this political belief affected the
scientific development of ideas about evolution in Russia.
Compare your answers with the ones in the answer pages.
Scientific evidence and Darwin’s theory
Darwin’s theory of natural selection explained all four types of evidence.
The discovery of new evidence – DNA and genes – helped to support
his theory even more.
As yet, scientists have not found any scientific evidence that refutes Darwin’s
theory so it continues to be accepted by most scientific communities.
But this does not mean that Darwin’s theory has not been altered.
New evidence had lead to small changes, producing the current theories
of evolution. You’ll learn more about these theories later.
What about non-scientific theories about evolution?
There are many, many non-scientific theories about evolution.
Some use scientific evidence to support them; others use
non-scientific evidence. They are all based on other viewpoints
or ways of looking at the world.
Would you like to find out about some of these other theories?
For example, you can access a website called The Talk. Origins
Archive that presents a range of ideas, from a link at:
http://www.cli.nsw.edu.au/kto12
How do non-scientific ideas influence scientific ideas?
Other viewpoints about many things have an impact of scientific ideas
and scientific developments. (Remember how political ideas in Russia
in the early 1900s affected Russian scientific ideas about evolution?)
Here are some more examples of how other viewpoints, such as
societal, religious and ethical viewpoints, have impacted on the
development of ideas about evolution.
Evolution Set 3
11
Cuvier and the idea of perfection
It was a common idea in Cuvier’s time that the world and everything
in it was perfect. This kind of idea comes from many religions.
Because Cuvier had this religious idea, he did not consider similarities
in features of organisms to be evidence of the evolution of populations
of organisms. His religious belief impacted on his scientific ideas.
Lamarck and Darwin and the idea of gradual improvement
The 1800s was a time of great change. Machines were making new
products and changing the way that people lived. There were big changes
in art and music. There was a feeling in society that things were getting
better and better. Both Lamarck and Darwin included this societal belief
about gradual improvement in their theories of evolution. They thought
that evolution was occurring to make organisms better and more complex.
Their societal belief impacted on their scientific ideas.
(Scientists no longer think that evolution causes improvement.
Evolution changes organisms to make them different, not better.
‘Better’ depends on the organism’s environment at that time.)
Current theories and our ideas of right and wrong
Ethical ideas about what is right and wrong are influencing current
scientific developments related to evolution and changes in genes.
For example, discussions about the ethics of cloning humans,
genetic engineering (changing the genes in organisms) and the
human genome project (identifying all of the code in human DNA)
have an influence on what current scientists think and do.
Darwin as an example
The development and acceptance of Darwin’s theory of evolution is
often used as an example of how societal, religious and ethical values
impact on science. Would you like to find out more about this?
There is a great deal of information about Darwin in biology
textbooks. You’ll also find plenty of information on the Internet.
You can access some websites to collect more ideas and information
from links at: http://www.cli.nsw.edu.au/kto12
Evolution Set 3
12
Now it is time to use ideas from Lessons 12 and 13 and from
throughout the unit to complete some send-in exercises.
Exercises 12.1, 12.2 and 12.3
Complete these exercises now.
Evolution Set 3
13
Lesson 14
New evidence, new theories
One of the problems for Cuvier, Lamarck and Darwin was that
they could not explain how characteristics were passed from parents
to offspring. It was not until around the beginning of the twentieth
century that scientific theories and laws about reproduction and
inheritance were developed to match the scientific evidence.
How are characteristics inherited?
In 1900, scientific investigations by an
Austrian monk named Gregor Mendel
were understood and accepted by the
scientific community in Europe.
(Mendel conducted his research
during the 1860s but it was not
recognised as important at that time.)
Mendel’s theory was that characteristics
of organisms were due to particular
information stored in cells.
This information could be passed
from an individual to its offspring
in its sex cells.
Each organism had two copies of the information; one had come from
each parent. The information from the parent did not change but was
passed intact from parent to offspring and so on. Whether the feature
appeared in an individual depended on which kind of information
the organism inherited and whether the information was dominant
or recessive.
Does Mendel’s theory ring bells in your head? Does it make you
think of genes and DNA? Mendel had discovered the evidence
that sent scientists looking for structures in cells that could carry
information from parents to offspring. This lead to the discovery
of chromosomes, genes and DNA and to the branch of science
called genetics.
Evolution Set 3
14
Discoveries in genetics have very important implications for theories
of evolution. Try these tasks.
1.
Why do you think that the discovery of genes made of DNA
helped to show that Lamarck’s theory should be rejected?
2.
Why do you think that the discovery of genes made of DNA
helped to show that natural selection could change the features
in a population?
Check your answers before you continue.
DNA is a very stable chemical substance.
It can be copied (replicated) over and over,
millions and millions of times, and every time
it is exactly the same.
This means that every cell in an organism’s body
has the identical copy of genetic information
about how to grow and develop. The cells can
work together to help the organism to survive
and reproduce.
The double helix
structure of DNA
Segments of DNA
code information
for particular features.
These segments
are called genes.
It also means that if that organism reproduces, identical genes will be
passed to offspring. The offspring will inherit genes that should
make them well-adapted for that environment.
So, the stability of DNA and the evidence that it replicates exactly
both support Darwin’s theory of evolution by natural selection.
Evolution Set 3
15
How do new characteristics occur?
The discovery of DNA and its complex structure led to another
major discovery – mutations.
DNA replicates exactly, except just sometimes when there is a
mistake or change. These mistakes are examples of mutations.
When DNA changes, the information it carries is slightly different
and may produce a slightly different feature in the organism.
(And because DNA normally replicates exactly, the mutation can be
passed on to offspring.)
Mutations can also be caused by chemicals (carcinogens) and by
electromagnetic radiation (such as gamma rays, X-rays and UV light).
Because DNA is so complex and it is replicated so many times,
small changes in DNA – mutations – are fairly common. For example,
you probably have about 100 mutations in your DNA.
Of these, three to five may end up causing you a disease.
That is the main problem with mutations – some of them are harmful.
But most mutations have no effect at all. And depending on the
environment, some mutations are beneficial, or helpful.
Mutations are important for producing the variation of features
observed in a population. This variation is essential for natural
selection to be able to occur. On rare occasions, mutations can
produce entirely new genes that give new features to organisms.
Mutations do not happen because organisms need a new feature or
because the environment has changed. Mutations just happen.
Organisms with mutated genes that make them better adapted
to the environment are able to survive and reproduce, passing on
the mutation.
Some examples of mutations that help organisms to survive and
reproduce in particular environments include antibiotic resistance
in bacteria and sickle-cell shaped human red blood cells, which
protects ‘sufferers’ against malaria.
Exercise 14
Using information from pages 14 and 15 only, answer the questions
in this send-in exercise.
Evolution Set 3
16
Adjusting Darwin’s theory of evolution
Here is some extra reading about current theories of evolution.
It would be a good idea to read this if you plan to study Stage 6 Science.
The discovery of genes and DNA changed how Darwin’s theory was
explained. So although modern theories of evolution are strongly based
on Darwin’s theory, they also take into account new evidence and ideas.
(There are a variety of these slightly different new ideas being discussed
and debated within the scientific community. That is why this unit
refers to current theories of evolution and not just to one modern theory.)
There are three main ways that current (or modern or contemporary)
evolutionary theories are different from Darwin’s theory.
•
As already noted, the reasons that evolution occurs are now
explained in terms of genes and DNA.
(Darwin did not know about these.)
•
Darwin thought that it was fairly easy for new species to form.
Modern theories say that many, many small mutations and
selection based on these small mutations (microevolution)
can cause large changes (macroevolution) over a very long period
of time.
Darwin thought that populations of organisms changed in a
steady progression. Modern theories say that species become
different over a relatively short time, then continue to change
more slowly. (This is called punctuated evolution.)
•
Scientists think that natural selection is only one of the reasons
that evolution occurs. Other reasons include:
–
mutations
–
genetic drift, where genes can disappear from small populations (For
example, there is a 50:50 chance of a baby being a boy or
a girl. But some families have all boys; others have all girls.
This randomness happens with genes too. It can mean that
some genes ‘accidentally’ disappear altogether from a population.)
–
gene flow, where genes from different populations are shared
so that even unfavourable genes may remain in a large population
–
non-random mating (For example, in some animal communities,
the only male that mates is the dominant male so only the
dominant male’s characteristics are passed on.)
The scientific explanation for the evolution of life on Earth continues
to evolve as new scientific evidence is identified and new hypotheses
are developed.
Evolution Set 3
17
Lesson 15
Selection to extinction
Throughout Earth’s history, extinction has mostly happened by chance.
Changes in the environment have favoured some organisms more than
others. Sometimes environmental changes occur gradually; sometimes
they happen very quickly.
Organisms that are better suited to the changed environment are
able to survive and reproduce while less suited organisms do not.
Groups of organisms that are not suited to the changed environment
may decline in numbers and eventually become extinct.
More recently, the activities of humans have caused the extinction
of many organisms. Humans are changing many environments,
over relatively short periods of time, making them unsuitable for
whole communities of organisms. The rate at which species are
currently disappearing from Earth concerns us all.
The game of extinction
For this game, you will need:
•
•
•
•
•
•
a die (two of these are called dice) or make the spinner on page 25
a token, such as a button, to move around the gameboard
scissors
species boxes from page 21
page 23, to extract some information from the game as you play
pages 18 and 19, the gameboard. (Leave them in your booklet.)
What to do:
•
•
•
•
•
Begin the game with 100 small species ‘boxes’ from page 21.
Place your token on START and roll the die for each turn.
Follow the instructions attached to any space on the gameboard
where you land. (Use extra boxes from page 21 or page 25 when
you need to add new species.)
No matter what you roll on the die, always stop and follow the
instructions at a STOP HERE space.
Keep rolling the die and moving around the board until you reach END .
Complete the ‘Game progress sheet’ while you are playing the game.
Evolution Set 3
18
New species evolve
Add 40 boxes.
Mass extinction about
430 million years ago,
probably caused by
climate change.
Throw away 80%
ST
O
(8 boxes from every 10)
P
HE
of your species.
RE
START
New species evolve
Add 30 boxes
if you land here.
New species evolve
Add 20 boxes
if you land here.
Minor extinction
Throw away 10 boxes.
The game
of extinction
Extinction of many species, mainly
due to humans destroying habitat and
introducing species from other environments.
Throw away 80% (8 boxes from every 10)
of your species.
END
STOP HERE
Extinction of many species
50 thousand years ago due to hunting
and changes caused by humans.
Throw away 30% (3 boxes from every 10)
of your species.
New species evolve
Add 1 box.
New species evolve
Add 30 boxes.
Minor extinction
Throw away 10 boxes.
STOP HERE
Minor extinction
Throw away 2 boxes.
Evolution Set 3
19
Minor extinction
Throw away 10 boxes.
S
T
O
P
H
E
RE
Mass extinction about
370 million years ago,
perhaps caused by
changes in sea levels and
chemicals in sea water.
Throw away 80%
(8 boxes from every 10)
of your species.
New species evolve
Add 40 boxes.
Minor extinction
Throw away 20 boxes.
New species evolve
Add 50 boxes.
New species evolve
Add 40 boxes.
New species evolve
Add 30 boxes.
Mass extinction about
250 million years ago,
perhaps caused by
massive volcanic eruptions.
Throw away 90%
(9 boxes from every 10)
of your species.
STOP HERE
Mass extinction about
65 million years ago ending
the reign of dinosaurs,perhaps
due to a meteorite collision.
Throw away 70%
(7 boxes from every 10)
of your species.
ST
OP
HE
RE
New species evolve
Add 50 boxes.
New species evolve
Add 50 boxes.
New species evolve
Add 30 boxes.
Minor extinction
Throw away 10 boxes.
Minor extinction
Throw away 10 boxes.
New species evolve
Add 40 boxes.
ST
O
P
New species evolve
Add 50 boxes.
Evolution Set 3
HE
RE
Mass extinction about
200 million years ago;
cause unknown.
Throw away 80%
(8 boxes from every 10)
of your species.
20
Clarifying ideas from the game
Complete this page once you have played the game. You need your answers
from page 23 to complete this page. You will also need to look at the gameboard.
(a) Define extinction.
(b) How does the game model the chance nature of extinction?
(c) Extract information from the game about how species appear and disappear.
(d) What are some causes of natural mass extinctions?
(e) Compare the impact of humans with mass extinctions in Earth’s past.
(f) Recommend how human activity must be modified to protect the number
and variety of species on Earth. (The number and variety of organisms
on Earth is often referred to as biodiversity.)
(g) How is this game different from what really happens? (Evaluate the game.)
Check your answers.
Exercise 15
Complete this send-in exercise now.
Evolution Set 3
21
Species sheet
Each small numbered box below represents approximately the same number
of species. You can think of each box representing a thousand species.
The number is not as important as the idea that many species
are involved in the changes you are modelling in this game.
The boxes are numbered to help you to count how many ‘boxes’
of species you have.
To start the game, cut the boxes apart on the double lines to make
four large blocks of boxes. You can cut these blocks into strips or
sections to add or remove boxes during the game.
There are extra boxes on page 25 if you need them.
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Evolution Set 3
22
Evolution Set 3
23
Game progress sheet
Answer these questions as you progress through the game.
1.
How many boxes of species do you have
at the beginning of the game?
______________
You should have 100 (10 rows of 10 boxes).
2.
3.
4.
5.
6.
7.
8.
How many boxes of species do you have
after the mass extinction, 430 million years ago?
______________
How many boxes of species do you have
after the mass extinction, 370 million years ago?
______________
How many boxes of species do you have
after the mass extinction, 250 million years ago?
______________
How many boxes of species do you have
after the mass extinction, 200 million years ago?
______________
How many boxes of species do you have
after the mass extinction, 65 million years ago?
______________
How many boxes of species do you have
when humans began hunting, 50 thousand years ago?
______________
How many boxes of species do you have
at the end of the game (in the present time)?
______________
Now think about these questions.
9.
Do you think you would get different answers to the questions
above if you played the game again? Explain.
10. Try the game again.
Did your answers to Questions 2 to 8 above change?
Evolution Set 3
24
Evolution Set 3
25
Making a spinner for the game
If you do not have a die, you can make the following spinner.
Cut around the outline
of the hexagonal spinner.
Push a toothpick or match
through the centre of the spinner.
You may need to use some
sticky tape to hold the spinner
onto the toothpick.
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4
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6
1
Quickly turn the spinner by
twisting the toothpick between
your thumb and a finger.
The number you use is the one
closest to the tabletop when
the spinner stops.
2
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Evolution Set 3
26
Evolution Set 3
27
Send-in page
Name
______________________________
Checking your progress
Tick the things below that you can do.
Then send this page to your teacher.
❒
❒
❒
❒
❒
❒
❒
❒
❒
evaluate the theories proposed by Cuvier and Lamarck
discuss evidence for evolution of life on Earth
construct diagrams to explain evolution by
natural selection
use the theory of natural selection to explain
how evolution occurs
identify advantages and disadvantages of DNA changing
describe how ideas come to be accepted by groups
of scientists
identify examples where non-scientific ideas
have impacted on science
extract information from a game
discuss how humans can limit their impact
on environments
Congratulations!
Evolution Set 3
Signed:
28
Evolution Set 3
29
Suggested answers
Lesson 11
Page 2
Darwin's theory
Natural variation
1.
B
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C
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D
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Prawn A has different antennae (whiskers) from prawn B.
Prawn A has longer antennae than prawn B.
Prawn A has longer and thinner antennae than prawn B.
Prawn A has longer and thinner antennae, and longer legs on its
body, than prawn B.
Prawn A has different antennae (whiskers) from prawn C.
Prawn A has shorter antennae than prawn C.
Prawn A has shorter antennae than prawn C. Prawn A also has a
shorter pair of legs attached to its head than Prawn C.
Prawn A has shorter antennae than prawn C. Prawn A also has
its third pair of legs attached to the head that are shorter than those
of Prawn C.
Prawn A is a different colour from prawn D.
Prawn A is a darker colour than prawn D.
Prawn A is the same darker colour all over but prawn D is a
lighter colour that varies. Prawn D is slightly darker along the top
of its back but very light near its legs.
Natural selection
Page 3
3.
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4.
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B (or D) because it has short antennae.
B because it has short antennae and short legs.
B because it has short antennae and short legs, and because it is
dark-coloured.
B because it has short antennae and short legs so that it can swim
quickly through the weed to escape from fish. It is also dark-coloured
so it can more easily hide in a dark-coloured lake.
The prawns could gradually become lighter.
The prawns could gradually become lighter and have shorter
antennae and legs.
The prawn population could gradually change so that individuals
are lighter and have shorter antennae and legs.
Evolution Set 3
30
•
Page 5
Light-coloured prawns with short antennae and legs would be
better suited to the lake. They would be more likely to survive and
reproduce so the prawn population could gradually change so that
most, or even all, individuals are lighter and have shorter antennae
and legs.
Review of Darwin’s theory
5.
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6.
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Natural selection means that nature selects which living things
stay alive and have babies.
Natural selection means that the environment chooses which living
things stay alive and have babies.
Natural selection means that conditions in the environment choose
which organisms survive and reproduce.
Natural selection means that conditions in the environment choose
which organisms survive and reproduce. Organisms that survive and
reproduce are able to pass their characteristics on to their offspring.
Natural selection means that conditions in the environment choose
which organisms survive and reproduce. Organisms that survive and
reproduce are able to pass their characteristics on to their offspring.
These offspring are also more likely to be able to survive and reproduce
in the same environment.
Evolution occurs because the fittest survive and reproduce.
Evolution occurs because the fittest survive and reproduce.
Less fit organisms die or are killed without reproducing.
Evolution occurs because organisms that are best adapted to their
environment survive and reproduce. Organisms that are not as
well adapted die or are killed without reproducing.
Organisms gradually change over time because the ones that are
best adapted to their environment survive and reproduce.
Organisms that are not as well adapted die or are killed without
reproducing.
Organisms gradually change over time because the ones that are
best adapted to their environment survive and reproduce. They
pass on their favourable adaptations to their offspring so that they
too are more likely to survive and reproduce in that environment.
Organisms that are not as well adapted die or are killed without
reproducing and so do not pass on their characteristics.
Evolution Set 3
31
Lesson 11 continued
Page 6
7.
There are many different ways to draw diagrams for this answer.
You can make your diagrams fun and interesting if you like.
They should also be neat and you’ll find them easier to draw if you keep
them simple (unless you are using a computer, like me!).
But the important thing is the scientific information that you show.
Here is an example of a good answer. Extra comments have been added
to point out some features of these diagrams.
Many offspring are produced in a population.
Although these individuals are very similar,
they are different from each other.
all the same kind of organism
a large number of individuals
variation (differences) between individuals
Individuals that are adapted to their environment
tend to stay alive. Individuals that are less suited
to the environment die or are killed.
some organisms with similar features survive
most individuals die
Individuals that survive are able to reproduce.
They pass their features, which have helped them
to survive, on to their offspring.
offspring resemble parents
variation in offspring
So, there is a gradual change in the features
of individuals in the population.
population with features that are different from the original population
variation in population that could lead to more natural selection
Evolution Set 3
32
Lessons
12 and 13
The importance of evidence
Scientific evidence and Lamarck’s theory
Pages
1.
Scientists have to agree that the theory explains the available evidence.
There must not be evidence that scientists agree refutes the theory.
However, not all groups (communities) of scientists throughout the
world have to agree with each other about the theory or the evidence.
2.
(a) Lamarck’s theory is the idea that organisms can pass on
characteristics that they have acquired during their lifetime to
their offspring.
9 & 10
(b) Their political belief affected how Russian scientists viewed the
evidence (because the observations you make depend on your
viewpoint). Scientists were also prevented from using or
investigating any theory of evolution other than Lamarck’s theory.
Lesson 14
New evidence, new theories
How are characteristics inherited?
Page 14
1.
Features of an individual are caused by genes. An organism would not
make a new gene in every cell just because it had changed in some way
during its lifetime. New genes could not be made and passed on to
offspring so acquired features could not be inherited.
2.
Organisms in a population are different because they have different
genes. The organisms that are able to survive and reproduce pass their
genes on to their offspring. The population gradually gets more and
more individuals with these genes and the features caused by the genes.
Organisms that die without reproducing do not pass on their genes and
so their genes gradually disappear from the population along with the
features caused by these genes.
Evolution Set 3
33
Lesson 15
Page 20
Selection to extinction
Clarifying ideas from the game
(a) Extinction means the dying out of a species. The species disappears
forever from Earth (because it cannot survive and reproduce).
(b) The chance nature of extinction is modelled by rolling a die to see what
happens.
(c) New species are constantly appearing throughout the game, due to
evolution. Existing species are constantly disappearing because they
become extinct.
(d) Some possible causes of the mass extinctions in Earth’s past include
climate change, changes in sealevels and chemicals in sea water,
volcanic eruptions and meteorite collisions.
(e) Humans are causing as many extinctions as the major mass extinction
events in Earth’s past.
(f) Humans will have to change what they do to Earth’s environments.
They will have to reduce the changes that they make to environments.
For example, they need to reduce the destruction of habitats and stop
introducing new species into existing environments.
(g) The game is a model based on scientific information. It may have
worked for you or, by chance, it might have given you a picture of
extinction that is different from the real situation. The biggest problem
with the model is that there need to be many, many more steps with
more species evolving. Hopefully you enjoyed learning from the game,
while recognising that the current extinction rate is serious (not fun).
Evolution Set 3
34
Evolution Set 3
35
Send-in page
Lesson 11:
Name
______________________________
Darwin’s theory
Exercise 11
In your answer below, you will relate natural selection to the theory
of evolution.
How does natural selection account for evolution?
Evolution Set 3
36
Evolution Set 3
37
Send-in page
Name
Lessons 12 and 13:
______________________________
The importance
of evidence
Exercise 12.1
Cuvier was a socially and politically capable French scientist of the
early 1800s. (He managed to work for all sides of politics through the
period of the French Revolution, without losing his head!)
Lamarck was much less able to put himself and his ideas forward.
He too was a French scientist of the early 1800s.
Darwin came from a different culture. He was an English scientist of
the early and mid 1800s.
1.
Identify one scientific idea that was contributed by each of these
seventeenth century scientists.
2.
Evaluate Cuvier’s theory of evolution.
3.
Evaluate Lamarck’s theory of evolution.
Evolution Set 3
38
Exercise 12.2
You need to think carefully as you prepare your answer for this task.
You have not been given the answer before. You will have to
construct an answer using information from throughout the unit.
It will probably help you to think about how evidence supported or
refuted Cuvier’s, Lamarck’s and Darwin’s theories of evolution.
Here is the task.
Discuss evidence that present-day organisms have developed
from different organisms in the distant past.
In your answer you will need to identify different kinds of evidence
for evolution of life. You will need to explain how each kind of
evidence supports the idea that present-day organisms have evolved
from different organisms in Earth’s past. You will also need to
explain any ways that each kind of evidence may not support the
idea that organisms have evolved.
Plan your answer carefully. It would be a good idea to draft it on
your own paper. Then present your answer on the following page(s).
You may choose to present it as sentences and paragraphs,
as a diagram or in another way.
Evolution Set 3
39
Send-in page
Name
Lessons 12 and 13:
Exercise 12.2
______________________________
The importance of
evidence (continued)
(continued)
Use the lines below and/or the blank space opposite for your answer.
Evolution Set 3
40
Exercise 12.3
Outline how the scientific ideas of Cuvier, Lamarck or Darwin
(or their followers) were influenced by societal, religious or
ethical values.
Evolution Set 3
41
Send-in page
Lesson 14:
Name
______________________________
New evidence, new theories
Exercise 14
Use information from pages 14 and 15 only to answer these questions.
Your answers summarise information from these pages.
1.
What are two disadvantages of DNA mutating?
(Or, what are two advantages of DNA replicating exactly?)
2.
What are two advantages of DNA mutating?
Evolution Set 3
42
Evolution Set 3
43
Send-in page
Lesson 15:
Name
______________________________
Selection to extinction
Exercise 15
1.
Describe how human activities are affecting the evolution
of Earth’s organisms.
2.
(a) What do humans need to do to reduce their impact on the
species of organisms on Earth?
(b) Propose how the things you have recommended above
would change how humans live and what they can do.
Evolution Set 3
We need your input! Can you please complete this short
evaluation to provide us with information about this unit. This
information will help us to improve the design of these materials
for future publications.
1.
Did you find the information in the unit clear and easy to
understand?
_________________________________________________________
_________________________________________________________
_________________________________________________________
2.
What sort of learning activity did you enjoy the most? Why?
_________________________________________________________
_________________________________________________________
3.
Name any sections you feel need better explanation (if any).
_________________________________________________________
_________________________________________________________
4.
Were you able to complete each part in around 5 hours? If not
which parts took you a longer or shorter time?
_________________________________________________________
_________________________________________________________
5
Do you have access to the appropriate resources? This could
include a computer, graphics calculator, the Internet,
equipment and people to provide information and assist with
the learning.
_________________________________________________________
Evolution
Evaluation
Centre for Learning Innovation
NSW Department of Education and Training
51 Wentworth Road
Strathfield NSW 2135