Download Workbook: Shaping the Earth and Life

Workbook 2: Shaping the Earth
and Life
NSWTSCN205A Undertake scientific investigations into
energy and fossil fuels
Contents
How old is Earth? .................................................................................................................. 3
The Structure of the Earth ..................................................................................................... 4
Activity 1: The structure of earth ........................................................................................ 5
How has earth’s surface changed? ....................................................................................... 6
Weathering and Erosion ................................................................................................. 6
Volcanic activity .............................................................................................................. 6
Activity 2: The changing earth ............................................................................................ 7
Activity 3: The changing surface ........................................................................................ 8
The rock cycle ....................................................................................................................... 9
Activity 4: Rock cycle ........................................................................................................10
Activity 5: Uluru .................................................................................................................11
Scientific evidence of the evolution of life .............................................................................12
Activity 6: The Changing Face of Australia ........................................................................13
Activity 7: Making a Mould ................................................................................................15
Activity 8: Similar Skeletons ..............................................................................................17
Darwin’s Theory of natural selection .....................................................................................19
Activity 9: Darwin’s Theory ................................................................................................21
Rabbits and Myxomatosis .................................................................................................23
Activity 10: Rabbits and Myxomatosis ...............................................................................24
Species can Change .....................................................................................................24
Biodiversity ...........................................................................................................................26
A Variety of Environments .............................................................................................26
Activity 11: Protecting the environment .............................................................................28
Activity 12: Classifying Living things..................................................................................28
Appendix: Training package information ...............................................................................29
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How old is Earth?
Earth is approximately 4.8 billion years old. For the first billion or so years of its existence,
Earth was a large blob of silicon compounds, and iron and magnesium oxides. It was
homogenous (the same composition all the way through).
Then, slowly over time, Earth’s structure changed. Earth became hotter and hotter and some
materials melted. Denser substances, such as iron, moved towards the centre of Earth while
less dense substances rose towards the surface. Earth became layered.
http://en.wikipedia.org/wiki/Earth
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The Structure of the Earth
The Earth is more than a large lump of rock, with air and water around its surface that
sustains life. Scientists have never seen the centre of the Earth but they have been able to
use their observations to infer what the inside of Earth must look like. Scientist have used
many types of evidence, such as:

observation of molten rock from volcanoes,

deep drilling into the Earth’s crust to obtain rock samples,

information from earthquake waves as they travel through the Earth.
It’s OK to have all these fantastic theories. Before science and technology got going, people
came up with our own ideas about the planet and the life on it. The Australian Aboriginal
Dreamtime provided ideas and stories which people used to explain the way things were. For
example: In Perth, the Noongar people believe that the Darling Ranges is said to represent
the body of a Wagyl – a serpent being. It is told the Wagyl meandered over the land, creating
rivers, waterways and lakes. The Dreamtime story also says that the Wagyl created the
Swan River.
The evidence suggests that the Earth is not uniform all the way through but is made up of
four layers.
http://www.csun.edu
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Activity 1: The structure of earth
Go to Earth Probe computer activity. Examine the internal structure
of the earth and then fill in the following table.
Layer
Make up
Temp
Pressure
Depth
Crust
Upper Mantle
Middle Mantle
Lower mantle
Outer Core
Inner Core
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How has earth’s surface changed?
Weathering and Erosion
The surface of Earth is constantly changing. Water, wind, temperature changes and chemical
conditions cause rocks to break and change. This process is called weathering. Then rain,
wind and flowing ice and water carry away material from weathered rocks, in a process
called erosion. The eroded material can settle in layers and, over time, form new
sedimentary rocks.
http://www.bbc.co.uk/schools/ks3bitesize/science/images/rock_cycle.gif
Volcanic activity
Volcanic activity also causes changes. Hot molten rock (magma) and gases from within
Earth can rise to the surface. New rocks, called igneous rocks, are formed when this molten
material cools. Heat from magma can also cause changes to other surrounding rocks. These
altered rocks are called metamorphic rocks.
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Activity 2: The changing earth
Look at the age of the coal layer in the diagram below. You can see how it is different in age
to the other rock layers shown. Then answer the questions below.
Bourne C, Science Directions 3, Harper Collins
Questions:
1. Define erosion.
2. Identify the three classes (groups) of rocks.
3. Classify sandstone. (Is it sedimentary, igneous or metamorphic?)
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Earth’s surface is also changing as the tectonic plates that make up the crust move, over
time. Here are the current positions of the main tectonic plates of Earth’s crust.
http://commons.wikimedia.org/wiki/File:Tectonic_plates.svg
Volcanic activity and earthquakes are most common at the edges of tectonic plates, where
the plates slide and rub together. This is also where mountain-building occurs as some
plates crumple into and slide under each other. Although the plates move very slowly (a few
centimetres each year), these changes become large over the long history of Earth. The
moving tectonic plates have carried the continents across Earth’s surface, changing and
reshaping them as they move.
Different continents are exposed to different climates as they move. This influences how
they are weathered and the kinds of new rocks that form. There have also been changes in
Earth’s climate during its history. For example, 18 000 years ago, Earth experienced an ice
age.
Activity 3: The changing surface
Justify the conclusion that Earth’s surface has changed over time.
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The rock cycle
In an attempt to understand the Earth and where fossil fuels come from, let’s have a look at
the rock cycle.
The Earth’s crust is not stable and unchanging. There is continuous, slight movement
occurring within the Earth’s crust. This, along with other factors like climate, results in longterm changes in the rocks within the crust.
The following diagram summarises the cycle of changes that occur in rocks over millions of
years.
Clark, H, Science Directions Book 3, Pearson Education Australia, p. 266
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Activity 4: Rock cycle
In your own words, write one paragraph explaining what the rock cycle shows.
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Activity 5: Uluru
Help Tylea find out how Uluru was formed. Got to Geology
of Uluru & Kata Tjuta at
http://www.ayersrockresort.com.au/geology
Read the information and summarise it in a diagram, like the
one on page 9.
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Scientific evidence of the evolution of life
Science is an organised body of knowledge as well as a process of finding and explaining
knowledge. Science has a set of ‘scientific’ rules that it uses to collect and assess
observations and to organise ideas.
Scientists always begin with evidence. One of the rules of science is that measurements
and observations of the world around us give accurate information about what that world is
like. The evidence that scientists have collected shows that organisms have changed over
time. So, from a scientific viewpoint, evolution of life is a fact.
A fossil of a mammal
http://commons.wikimedia.org/wiki/File:Fossil_mammal.jpg
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What sort of evidence have scientists collected?
As you read the following information, underline the examples of evidence to identify
them.
Evidence for evolution can be found in a number of areas:
a) The fossil record. Remains of living things preserved in sedimentary rocks are probably
the most obvious evidence that organisms have changed over time. The fossil record
shows a huge variety of organisms that have lived on Earth over the last 500 million
years. Only about 2% of species that have ever lived are represented in the populations
currently on Earth. New fossils are continually being found that give more information
about the links between organisms from the past, and their relationship with organisms
alive on Earth today.
Activity 6: The Changing Face of Australia
Watch the video The Changing Face of Australia at
http://aso.gov.au/titles/documentaries/changing-faceaustralia/clip1
Make a note of the type & age of rock, as well as the type of
animals that were fossilized.
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b) Body chemistry. All living things are made of similar chemicals – proteins, fats,
carbohydrates, water and mineral salts. All the cells of living things contain genetic
material and all this genetic material is made up of the same basic chemical building
blocks. All bones and shells, from very different animals, contain the same basic type of
chemical. Similar body chemistry suggests all organisms developed from a common
ancestor.
c) Embryo shape. The embryos of many animals grow inside the mother’s body. As they
develop, they may still look very much like their ancestors did, especially when they are
just starting to develop and they can be difficult to tell apart. This suggests these animals
developed from a common ancestor.
d) Seed leaf shape. Just as in the embryos of animals, the embryos of plants also show
strong similarities when the seeds are just beginning to germinate. This suggests these
plants developed from a common ancestor.
e) Skeletons of vertebrates. Although many vertebrates (animals with a backbone) have
external body shapes that are quite different, and can use their limbs in very different
ways, their skeletons have strong similarities. This suggests these animals developed
from a common ancestor.
f)
Similar structure. All living things are made of cells, as we have seen before. Although
there are differences between plant and animal cells, all cells are basically the same and
contain many of the same chemicals and chemical processes. This also suggests living
things have developed from a common ancestor.
g) Classification. The classification system we use shows how living things that are similar
can be grouped together. It also shows apparent lines of descent from common
ancestors.
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Activity 7: Making a Mould
http://commons.wikimedia.org/wiki/File:Eurypterus.jpg
Problem:
To make models of different types of fossils.
Equipment:
Polystyrene cup, spoons, petroleum jelly, water, various hard objects, and plaster of Paris.
Method:
1.
Spread newspaper over your work area or move outside to continue with this activity.
2.
Mix the plaster-of-paris according to the directions given by your teacher.
3.
Choose one of the hard objects and carefully smear a layer of petroleum jelly over its
entire surface.
4.
Quickly pour the plaster and water mixture into a polystyrene cup.
5.
Immediately press your hard object onto the surface of the. Make sure it is not too deep
into the mixture. Leave it there until the plaster has set.
6.
When the plaster has set, carefully remove the object from the plaster. You now have a
mould of the object.
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7.
Lightly coat the mould of the object with petroleum jelly or cover the mould with cling
wrap that you have smoothed out. Pour a small quantity of plaster of Paris with water,
following the instructions above.
8.
Pour the second batch of plaster into the mould of the object and allow it to harden. This
will produce a cast of the object.
9.
When the cast is hard, carefully remove it from the mould.
Discussion:
1.
How are moulds made in nature?
2.
Which rock group contains fossils? Why?
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Activity 8: Similar Skeletons
The diagram below shows six vertebrate forelimbs. Use your own paper.
1.
Next to each diagram, write down what the animal uses this limb for.
Brothers, B.H. Science teachers' resource book, Volume 3, Sapphire Books
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2.
Write down what similarities and differences there are in the bone structure of these
limbs.
3.
Write a brief statement explaining how this evidence supports the theory of evolution.
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Darwin’s Theory of natural selection
Charles Darwin (1809-1882) was an Englishman who, as a medical student, studied biology
and zoology. He volunteered as an unpaid scientific officer on the naval vessel, HMS Beagle,
which surveyed coasts and islands in South America and Australia in
1831-1836. During that time, he observed many plants and animals
and was struck by the amount of variation he saw in the same or
similar species.
http://commons.wikimedi
The illustration below shows some of the birds Darwin studied on
the Galapagos Islands. He not only found that birds that were
isolated from each other on islands with different trees and insect life
had different features, but he suggested that isolation was the factor
that led to these differences being developed.
a.org/wiki/File:Charles_D
arwin_1880.jpg
Galapagos tree finches (a) and ground finches (b).
Brothers, B.H. Science teachers' resource book, Volume 3, Sapphire Books
Darwin explained evolution using a hypothesis called natural
selection.
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His model is based on four premises:

There are more organisms born than are able to survive.

Organisms of the same type have natural variations.

The organisms best suited to the environment survive.

The survivors pass on their characteristics to their offspring.
The features that determine which organisms will survive are those that make them best
suited to their environment. If the environment changes, different features may help
organisms to survive and these will be the ones that are favoured or selected by the
environment.
In Darwin’s hypothesis the features are selected due to survival advantage in the
environment, not because the organism wants to change. This is why it is called natural
selection - nature selects the features that aid survival (also known as ’survival of the fittest’,
where that word means ‘best suited’, rather than ‘strongest’).
Darwin did his work long before anything was known about genetics, so he could not explain
how variations occurred or how characteristics were passed on. Nevertheless, he was able
to describe the selection process in detail, as in the following example.
Imagine there is a population of frogs in a
pond, all the same type. They have toe pads to
help them cling to surfaces when hunting for
food. Some of the frogs have smoother pads
than others that don’t stick as well to the
surfaces in the frogs’ environment. The only
source of food for the frogs is insects that
gather around a moss-covered rock face.
The frogs with the smooth toe pads cannot cling
to the wall, so they can’t get enough food,
become weak and die. The frogs with the
http://commons.wikimedia.org/wiki/File:Frogsvxd.jpg
rougher toe pads can cling to the wall and get
plenty of food. These frogs become big and
strong, mate and produce more frogs. A greater proportion of their offspring will have rougher
toe pads, because these characteristics were inherited from their parents. Over time, all frogs
of this species will have rougher toe pads.
However, the smooth-padded frogs need not be extinct - somewhere else, there may be a
pond surrounded by smoother rocks that give them a survival advantage over the roughpadded frogs. The reverse process would occur in this environment, and so a separate frog
species would come into being. The only species that became extinct was their more
versatile common ancestor.
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Darwin saw that a similar process must have affected the Galapagos finches, and he
extended his argument to greater differentiations between species over longer periods of
time. For example, all the great cats, lions, leopards, tigers, cougars, and so on, might have
had a common ancestor millions of years ago. Similarly, humans and apes might have
branched off from some now-extinct primate. (Darwin never suggested that humans had
evolved from present-day apes, as their ancestors and our hominid precursors evolved in
irreversibly different directions some five million years ago.)
Activity 9: Darwin’s Theory
Draw diagrams to complete this summary of Darwin’s theory.
1. Many offspring are produced in a population. Although these individuals are very
similar, they are different from each other.
2. Individuals that are adapted to their environment tend to stay alive. Individuals that
are less suited to the environment die or are killed.
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3. Individuals that survive are able to reproduce. They pass their features, which have
helped them to survive, on to their offspring.
4. So, there is a gradual change in the features of individuals in the population.
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Evidence for natural selection can be found in a number of areas,
mainly from observing changes within populations that breed or
reproduce very quickly.
Rabbits and Myxomatosis
Rabbits were introduced into Australia in 1830. They are good news for hunters and fur
trappers, but for farmers and native wildlife, rabbits have proved to be a disaster.
http://commons.wikimedia.org/wiki/File:Wild_rabbbit,_cut.jpg
Rabbits breed very quickly and their populations can grow to an enormous size in a
relatively short period of time. They live in warrens in the soil, which means the soil is
disturbed and can then be easily eroded.
When rabbit populations become very high and then dry weather follows, they eat anything
that is available including small trees and shrubs, which can permanently damage plants.
The lack of plant cover aggravates any erosion problem.
In the early 1950’s, the Myxomatosis virus was introduced into Australia. It was spread by
mosquitoes and fleas. It causes blindness in rabbits, which means they cannot find food, so
starve to death. When it was first introduced, Myxomatosis caused the rabbit population to
plummet. However, about one percent of rabbits survived the virus. They were immune to it
and so were their offspring.
In recent years, the rabbit population in Australia has again reached worrying and destructive
levels. The most recent weapon use to control their population is the Calicivirus.
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Activity 10: Rabbits and Myxomatosis
1.
Was the Myxomatosis virus a success at controlling rabbit numbers in Australia? Explain
your answer.
2.
Explain how our experience with rabbits supports the idea of natural selection.
Species can Change
One of the main ideas Darwin stressed in his theory was that species could change. Two
organisms belong to the same species if they can breed and produce fertile offspring.
Therefore, all humans belong to the same species, Homo sapiens. Yet there are few humans
that look identical. Even identical twins have small differences that can be used to tell them
apart.
Our genetic make-up controls what we are, what we look like and how we function. The
cells of all living things contain the genes that give identity to each organism. Every species
has a range of different individuals with slightly different genes.
Darwin didn’t know about genes; it was at least another 20 years after the publication of his
book before another scientist, Gregor Mendel, performed a range of experiments, which
demonstrated that characteristics were passed on from parents to offspring. However,
Darwin did understand that, within one species, there exists a range of different
characteristics.
Other scientists provided Darwin with fuel for his ideas. At around the same time as Charles
Darwin was forming the Theory of Evolution, another man was developing a new
classification system for all living things. Linnaeus’ system was so logical it is still in use
today, though it is constantly being modified. Darwin could see definite patterns in the way
living things were both similar and different.
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Here is a brief summary of Linnaeus’ classification system.
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Biodiversity
‘Bio’ is from the Greek bios, meaning ‘life’ ‘Diverse’ means there is a variety in the
population. There are well over one million species of animals and 300 000 species of plants
so far identified. Organisms range in diversity from huge animals, such as killer whales, to
carnivorous plants and microscopic bacteria. Some organisms can make their own food
using energy from sunlight, some eat other plants or animals, and others derive nutrition from
breaking down dead organisms. The huge number and diversity of organisms on Earth exist
due to the many different environmental niches in which they can live.
http://commons.wikimedia.org/wiki/File:CarolinePic-Kepler-Mannikiba.jpg
A Variety of Environments
Maintaining a variety of environments on Earth is vital for the continuation of diverse species.
If human activities damage particular environments, then this can lead to certain species
becoming endangered or being made extinct. Even by natural selection, evolution is a slow
process and human activity can change environments too quickly for the local organisms to
adapt to those changes.
Biodiversity needs to be preserved because we cannot anticipate future climatic and
environmental changes. The extinction of even some obscure species of weed or insect may
mean the permanent loss of genetic characteristics that could be valuable under the right
circumstances.
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The Australian Aboriginal people are credited as been the original
carers and promoters of Biodiversity. It may sound strange, but
the regular burning off, of the grasslands has been shown to be
beneficial to the organisms and the ecosystem of that area.
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Activity 11: Protecting the environment
Read about ‘fire-stick farming’ among the Martu people of
Australia's Western Desert. Go to:
http://scienceblogs.com/notrocketscience/2008/09/aborigines_improv
e_biodiversity_by_starting_fires.php
Watch Caring for Country, the story of the Bardi Jawi community
located near Broome, who are a dedicated group of residents, who
have pioneered a program to protect their country and preserve the
wildlife in it. Go to:
http://player.sbs.com.au/naca/#/naca/living_black/Latest/playlist/Carin
g-For-Country
Activity 12: Classifying Living things
Classify each of the living things in the table below according to where they fit in Linnaeus’
classification system.
.
Living things
Plant/Animal
Vertebrate/Invertebrate
OR Seeds/no seeds
Classification
Platypus
Rose
Lion
Scorpion
Apple
Jellyfish
Whale
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Appendix: Training package information
Elements and Performance Criteria – NSWTSCN205B
Element
1. Briefly outline the
processes shaping
the earth and
evolution of life.
Performance Criteria
1.1
1.2
1.3
1.4
1.5
NSWTSCN205B: Workbook 2 © DET NSW
Outline briefly the main processes related to the
formation and structure of the earth.
Identify rock types and describe the rock cycle and fossil
formation.
Outline briefly, scientific theory for the Evolution of life on
Earth.
Examine evidence for changes in life forms over time.
Explain what biodiversity is, and use classification
systems to group organisms.
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