Life Sciences - Evolution
Life Sciences - Evolution
1. Introduction 3
2. How to use this Self-study Guide 4
3. Evolution 5
3.1 Key concepts/Mind maps 5
3.2 Terminology 6
3.3 Notes/exam tips/techniques 8
3.4 Exam tips/techniques/notes 11
3.4.1 Variation 12
3.4.2 Mechanisms of reproductive isolation 12
3.4.3 Lamarck’s theory 15
3.4.4 Natural selection (Darwin’s theory) 17
3.4.5 Speciation 18
3.4.6 Human evolution 19
3.4.7 Phylogenetic trees 26
3.4.8 Out of Africa hypothesis 29
4. Typical exam questions 33
5. Solutions 43
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1. INTRODUCTION
The declaration of COVID-19 as a global pandemic by the World Health Organisation led to the
disruption of effective teaching and learning in many schools in South Africa. The majority of learners
in various grades spent less time in class due to the phased-in approach and rotational/ alternate
attendance system that was implemented by various provinces. Consequently, most schools were not
able to complete all the relevant content designed for specific grades in accordance with the Curriculum
and Assessment Policy Statements in most subjects.
As part of mitigating against the impact of COVID-19 on the current Grade 12, the Department of Basic
Education (DBE) worked in collaboration with subject specialists from various Provincial Education
Departments (PEDs) developed this Self-Study Guide. The Study Guide covers those topics, skills and
concepts that are located in Grade 12, that are critical to lay the foundation for Grade 12. The main aim
is to close the pre-existing content gaps to strengthen the mastery of subject knowledge in Grade 12.
More importantly, the Study Guide will engender the attitudes in the learners to learning independently
while mastering the core cross-cutting concepts.
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2. HOW TO USE THIS SELF-STUDY GUIDE
o There are five Self- study Guides covering all Grade 12 topics:
o Booklet One: DNA: Code of Life and Meiosis
o Booklet Two: Reproduction in Vertebrates, Human reproduction, Endocrine
System and Homeostasis
o Booklet Three: Genetics and Inheritance
o Booklet Four: Responding to the Environment: Humans and Plants
o Booklet Five: Evolution: Natural Selection and Human evolution
o You must use this Self-study Guide together with the Life Sciences Mind the Gap Study
Guide.
o You need to study the content from the DBE Grade 12 Textbook, DBE Examination
Guidelines 2021, and Mind the Gap for all the topics.
o Ensure you understand all the relevant concepts and content.
o This Self-study Guide focuses mainly on the skills you will need to answer the
questions in examinations.
o There are exam technique and tips for each topic (in italics)
o These tips will guide you on how to approach certain question types in the Life
Sciences Examination papers and tests:
o How to master the relevant terminology
o Drawing and interpreting of graphs
o Interpreting tables
o Interpreting diagrams
o Genetics crosses and pedigree diagrams
o Doing calculations
o Scientific investigation questions
o At the end of each booklet, you will find typical examination questions and answers
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1. TOPIC: EVOLUTION
TERM 3 PAPER 2
DURATION 8 hours WEIGHTING 54 marks
(3 weeks)
PRIOR-KNOWLEDGE/BACKGROUND KNOWLEDGE
Gr 10 History of life, classification, Grade 11 biodiversity in animals and plants, Grade 12 DNA, Meiosis
RESOURCES
DBE 2020 Textbook, MTG, Past NSC, SC & Provincial Question Papers
Fossils
Modification by descent
Genetics
Biogeography
Variation Speciation
Evidence
Articial selection
Species specific behaviour
Prevention of fertilisation
Infertile offspring
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Types of evidence Comparisons
-Fossil between humans
-Genetic and African apes
-Cultural
HUMAN
EVOLUTION
TERM DEFINITION
Acquired characteristic Is a characteristic that an offspring is not born with but which
develops/is acquired through the course of its lifetime; a
characteristic not controlled by a gene.
Artificial The breeding of organisms over many generations in order to
selection/selective achieve a desirable phenotype
breeding
Biodiversity The variety of plant and animal species on earth
Evolution The processes that have transformed life on earth from its earliest
forms to the vast diversity that characterizes life on earth today.
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The Theory of Evolution The Theory of Evolution is regarded as a scientific theory since
various hypotheses relating to evolution have been tested and
verified over time
Fossils The mineralized remains of organisms that have lived in the past
Genetic variation This includes a variety of different genes that may differ from maternal
and paternal genes resulting in new genotypes and phenotypes.
Homologous structures Pertain to the structures that show similar morphology and
anatomy but have different functions, believed to have developed
from a common ancestor
Hypothesis A tentative explanation of a phenomenon that can be tested and
may be accepted or rejected
Inherited characteristic Is a characteristic that an offspring is born with, having been
inherited from one of the parents; a characteristic controlled by a
gene.
Mutation A sudden change in the sequence/order of nitrogenous bases of a
nucleic acid
mya Million years ago,
Natural selection The process by which organisms best suited to survival in the
environment achieve greater reproductive success, thereby passing
advantageous characteristics onto future generations
Palaeontology Study of fossils
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3.3 LINKS TO PRIOR KNOWLEDGE
GRADE 10 LINKS:
• Classification in grade 10 taught you how to write scientific names. In human evolution, you must know the
difference between a family name, a genus and a species.
Source: https://www.evolutionarymodel.com/apps/photos
• In grade 10 you’ve learnt about fossils, which are the mineralised remains of past living organisms in rock.
The fossils are used to see how organism have changed from the past to now. An important concept in grade
12 evolution is transitional fossils that shows the changes between older organisms and the newer organism.
This concept will be used in human evolution.
The archaeopteryx is a
transitional fossil
between a dinosaur and a
bird.
source: Socrates.org
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• The geological timescale shows the history of life on Earth. There has been life on Earth for the past 4.5
billion years.
MESOZOIC
PALEOZOIC
Source: https://vectormine.com/item/geologic-timeline-scale-vector-illustration-diagram
• The diagram above is an example of a geological timescale that was done in grade 10.
• You don’t have to know the eras or periods or study this timescale.
• Observe how organisms evolved from less complex to more complex throughout the years.
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Snider-Pellegrini Wegener fossil map Source: Biologydictionary.net
The diagram shows the Lystrosaurus whose fossils are found in Africa, India and Antarctica.
The Glossopteris‘ fossils are found in Australia, Antarctica, Africa and South America.
The Mesosaurus and Cynognathus fossils are found in South America and Africa.
GRADE 11 LINKS:
- Evolution in present times links with micro-organisms and immunity that was done in grade 11.
- Bacteria and viruses (think of Covid-19) evolves quickly through genetic mutations into other strains. It
causes resistance to medication as the micro-organisms evolve too quickly.
• Malaria mosquitoes became resistant to insecticide.
• Tuberculosis bacteria became resistant to TB drugs because of mutations.
• HIV virus became resistant to ARV
-Phylogenetic trees are done with plant and animal biodiversity in grade 11. It shows the evolutionary links
between different organisms over a span of time
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GRADE 12 LINKS:
• Genetic evidence used for evolution is based on mutations that you’ve done in grade 12 DNA and protein
synthesis as well as in genetics. This evidence is used to indicate how closely organisms are related.
Scientists state that organisms are closely related and are likely to have a common ancestor if they have:
- Identical DNA structure
- Similar sequence of genes
- Similar portions of DNA with no functions
- Similar mutations. Mitochondrial DNA is used as evidence for human evolution. The mutation within the
mitochondrial DNA is used as markers.
Species that are closely related have a greater similarity to each other than distant species.
• Evolution also links to meiosis in grade 12 especially when you deal with variation. Crossing over and
Random arrangement are two processes in meiosis that deals with genetic variations.
Please note:
Only problematic topics identified by the DBE diagnostic report is discussed in this section. Refer to
DBE textbook and exam guidelines to study all the required topics.
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3.4.1. VARIATION
• Remember sources of varation:
CRRRM à crossing over, random arrangement, random fertilisation, random mating, mutations
• You need to know the difference between the types of variation, namely continuous and
discontinuous variation. They will give you examples and then you have to be able to distinguish
between them.
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4.Plant adaptation to different pollinators
(plants adapted to insects, wind and birds for
pollination- link back to grade 11)
5.Infertile offspring
(Example: when donkeys and horses mate they
produce mules who are infertile)
Scientists conducted an investigation to determine the relationship between the length of the male long-tailed
widowbird's tail and its mating success.
The average number of nests produced by each group was calculated and used as an indication of mating
success. A way to ensure reliability, calculating average
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The results are shown in the table below.
Not the
GROUP AVERAGE NUMBER OF NESTS PRODUCED dependent
1 0,5 variable, but
2 2,5 how they
3 1 measured it
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3.4.3. LAMARCK’S THEORY
Tip:
Read the questions first and then you read the case study. It helps you to focus when you read the
case study.
2.1 A gene mutation caused variation between the Tibetan population and the Han population. (3)
Name THREE other sources of variation in a human population.
The key word here is VARIATION Remember causes of variation is CRRRM:
Answer:
Crossing overP
Random arrangement of chromosomes meiosisP
Random matingP
Random fertilizationP
Chromosomal MutationP
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If you wrote meiosis, you got a mark, but then you didn’t get additional marks if you wrote crossing
over or random arrangement of chromosomes because it’s part of meiosis. Also, the question talks
about gene mutation, and they want other sources of variation, so that is why it should be
chromosomal mutation.
2.2
Give evidence from the extract which suggests that the survival of people living at high
altitudes could be: (1)
(a) Due to a genetically inherited trait (1)
(b) Caused by an environmental factor
You need to read the passage and find the evidence for this.
2.3 Explain the advantage of producing more red blood cells. (2)
This question links back to grade 11 and 10. Haemoglobin is a protein found in red blood cells that
carry oxygen in our blood to all the tissues etc. At High altitudes, there is less oxygen in the air than at
low altitudes (sea level).
Explain what the question wants you to answer in a cause-and-effect manner.
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What was the result? As a result, the ancestral Tibetians
produced more red blood cells/developed
ways to use oxygen more efficientlyP
To increase the availability of oxygen to
the bodyP
What happened to this new This acquired characteristicP
characteristic? was then passed on to their offspringP
What was the result of this All Tibetans now produce more red blood
cellsP / use oxygen more efficiently to
survive at high altitudes
There are 7 possible ticks, but you only need 5 as the question’s total is 5.
The environment or nature is the selective force. Humans represent the selective force.
Occurs within a species. May involve one or more species (as in cross
breeding).
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3.4.5. SPECIATION
Geographical isolation and reproductive isolation mechanisms, isolate the gene pool of a species
resulting with formation of new species
Source: evolution.berkeley.edu
In the diagram above the beetles are separated and after time speciation took place (natural selection
took place independently in each environment) and the green beetle species was formed in the top
environment and the browner beetle species was formed in the lower environment. They are no longer
able to mate and produce offspring.
4.1
3.2
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4.1 Explain how continental drift could have affected the distribution of the common
ancestor. (3)
Ask yourself what is continental drift – it is the separation of continents.
What is a common ancestor – it is a species that gave rise to other descendant species. So how could the
separation of continents affect the distribution of the common ancestor of these two mammals? They are not
asking to explain how the two mammals originated through speciation. They are asking about the common
ancestor:
4. 2 Describe the speciation of the pottos and lemurs to become different species. (6)
Now they asking you to explain the process of speciation starting from the common ancestor and
then working towards the pottos and lemurs. (don’t start with pottos and lemurs, they are the
result of speciation)
Answer:
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• natural selection occurs • And underwent natural selection
independently in each of the two independentlyP
populations
• such that the individuals of the two • The individuals in each group became
populations become very different differentP
from each other
• genotypically and phenotypically. • Genotypically and phenotypicallyP
• The two populations are now • To form the pottos and lemurs *P
different species. (Now you must be specific to the example
in the question, these two species originated
• Even if the two populations were to from the common ancestor due to
mix again speciation)
• they will not be able to interbreed. • Eventually if the two groups are mixed
again, they cannot interbreed/ produce
fertile offspring. (6)
2* compulsory (had to write them or lose 2 marks, always specify the geographical barrier
and in this case you have to mention the exmples) + 4 marks (any other four points)
Write full sentences!!!
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• You must know which scientist discovered the fossils of the three genera Ardipithecus,
Australopithecus and Homo (especially the South African ones, also where in South Africa they were
found.)
The table below summarizes the different fossils discovered as evidence for human evolutions. The
ones with the stars are South African.
wikipedia.org
Australopithecu 1,9-1,8 Malapa Cave Lee Burger Brain Size: 420 ml
s sediba mya – in the cradle Prognathous (less protruding)
(Karabo) of humankind Brow ridges
Large teeth; canines not long
Long arms
No cranial ridge
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Source:wordpre
ss
Homo habilis 2,2-1,6 Tanzania Louis and Brain size: 650 ml
(Handy man) mya Mary Leakey Prognathous (less protruding)
Source:Smithsonian
Less pronounced brow ridges
Human-like teeth; smaller canines
Long arms
Source: Britannica.
Homo sapiens 200 000 Makapansgat Tim White Brain size: 1200-1800 ml
years ago in Limpopo No brow ridges
- present Border Cave Small teeth
in KZN Short arms
Blombos Cave Non prognathous
in the Western
Cape
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• There is a difference between the skull and the cranium. The cranium is the part of the skull where the
brain is housed in.
• When talking about the differences between jaws of humans and African apes don’t refer to more or less
prognathous but rather use prognathous and non-prognathous
• Foramen magnum in humans is in a more forward position not in the center or in the front
• Bipedalism is the ability to walk on two lower limbs, not only limbs because arms are also limbs so you have
to specify lower or hind limbs.
5.1 Tabulate THREE observable differences between skull 1 and skull 2 that show trends in (7)
human evolution.
You can’t talk about bipedalism, foramen magnum, pelvic girdle, opposable thumbs etc. here. Only
what you can SEE!
SKULL 1 SKULL 2
Brow ridges pronouncedP Brow ridges less pronouncedP
More protruding jawsP/prognathous Less protruding jawsP/non-prognathous
Larger jawsP Smaller jawsP
Smaller cranium sizeP Larger cranium sizeP
Larger teeth/caninesP Smaller teeth/caninesP
Poorly developed chinP Well-developed chinP
Sloping faceP Flat face P
When you must tabulate your answer, ensure that you have the same trait per row. For example,
the first line is about brow ridges that you compare. You can’t have brow ridges underneath skull 1
and jaws underneath skull 2 in the same row.
There are 7 possible traits but only the first three are marked
Table P + (3 traits x 2)
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5.2 Give FOUR characteristics of the upper limbs that humans share with other primates.
This is from the syllabus, study your work!
• Freely rotating armsP
• Long upper armsP
• Rotation around elbow jointsP
• Rotation around the wristP
• Opposable thumbsP
• Bare fingertipsP/ nails instead of claws
• Five fingersP
• Fingerprints presentP
(4)
(Only your first four answers will be marked, make sure they are correct)
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PRACTICE QUESTION 6 (DBE November 2018 P2):
6.1. Describe ONE visible difference between the jaw of a chimpanzee and that of Homo sapiens
which show trends in human evolution. (1)
Underline the key words, one visible difference between a chimpanzee and Homo sapiens. They
only ask for one difference, so they will only mark your first answer. You need to look for a visible
difference from the diagrams given. You can’t talk about foramen magnum, prognathous, brow
ridge etc.
Based on the differences in dentition, what conclusion can be made about the change in diet
6.2. from Australopithecus afarensis to Homo sapiens?
Underline key words, differences in dentition, diet of A. afarensis and H. sapiens. Look at the teeth (2)
of only these two diagrams, how do the teeth differ and what will the size and shape of teeth
influence what they eat? The A. afarensis has bigger teeth so they can still eat tubers and raw
food. Our teeth are small, we cannot eat raw/tough food.
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6.3. Australopithecus may be described as a transitional species between the chimpanzee and (1)
Homo sapiens.
(a) Define a transitional species.
This links back to grade 10.
A transitional species shows intermediate characteristics between two genera /speciesü
OR
It has characteristics common to both the ancestor species and the species that followsü
(2)
Use ONE visible feature of the jaw to explain why A. afarensis may be described as a
6.4. transitional species.
Remember a visible feature is only what you can see. Now you have to compare the jaw
of the A. afarensis with the chimpanzee and human and see if there are intermediate characteristics
between them. Look at the size of the teeth and jaw, also the shape of the palate. It is important to
note that you have to compare the same feature in your answer, you can’t talk about the one
species’ jaw and the other species’ teeth.
The jaw is smaller than that of the chimpanzee but larger than that of Homo sapiensPü
OR
The canines/ teeth are smaller than those of the chimpanzee but larger than those of Homo
sapiensP
OR
The jaw/ palate shape is more rounded than that of the chimpanzee but less rounded than that of
Homo sapiensPü
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4.4.3. PHYLOGENETIC TREES
• In the diagnostic reports of the past eight years it was stated that learners don’t understand
phylogenetic trees.
• A phylogenetic tree is a diagrammatic representation of the evolutionary relationships between species.
• A phylogenetic tree is a schematic form that shows the evolutionary relationships within a set of
organisms or groups of organisms.
• Phylo = organism’s phylum group and genetic = from the genes/relationship between the genes
• It should not be confused with pedigree diagrams which is the genetic relationships between close
family members.
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When you look at the phylogentic tree above you will see a lot of branches.
• The first branching (speciation event) is at number 1. That is the common ancestor for all the species in
this phylogenetic tree.
• Let us look at the first branch:
• A, B and C have a common ancestor at number 2 and B and C have a common ancestor at 3.
• B and C are more closely related to each other than to A.
• A, B and C are more closely related to each other than to D, E, and F.
In the diagram above the Austropithecus afarensis is the common ancestor of Homo habilis and A.robustus
• When the line forks into branches, speciation takes place and new species originate. The organism
that existed when the line forked into branches is the common ancestor of the new species.
• When a line ends, it is the extinction of that specific species.(Refer to DBE textbook page 292)
• Look at the time line (either on x-axis or y-axis) to see how old an organism is. For example Homo
habilis originated 3mya ago.
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EXAMPLE QUESTION 7 (Gauteng September 2018 P2)
Fossil evidence for humans may be interpreted in different ways. One possible model of human
evolution is shown below.
Homo erectus
Paranthropus Paranthropus
robustus boisei Homo habilis
Time (millions of years ago)
Australopithecus
garhi Australopithecus
Paranthropus africanus
aethiopicusus
Australopithecus afarensis
Hominin ancestor
1.4.7 List TWO types of evidence that can be used to support the “Out of Africa”
hypothesis.
Australopithecus africanusP (2)
(10)
Ardipithecus ramidusP
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4.4.4. OUT OF AFRICA HYPOTHESIS
This hypothesis states that modern Homo sapiens evolved in Africa about 200,000 years ago and migrated
outwards to Europe and Asia, according to the Southern Dispersal theory.
Most scientists agree that modern humans (Homo sapiens) evolved in Africa and spread outwards across
the continents.
The following lines of evidence have been used to support this hypothesis:
• The oldest fossils of australopithecines/Homo habilis/bipedal organisms have been found in
Africa
• The oldest fossils of Homo erectus have been found in Africa
• Analysis of mitochondrial DNA shows that the oldest female ancestors of humans are from Africa
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Fossil Evidence:
• Ardipithecus fossil were found in Africa ONLY, nowhere else in the world. (so they originated in Africa)
• Australopithecus fossils found in Africa ONLY (Karabo, Littlefoot, Taung child and Mrs Ples all
originated in Africa)
• Oldest fossils of australopithecines, Homo habilis and other bipedal organisms were found in Africa
• Oldest fossils of Homo erectus and Homo sapiens were found in Africa, followed by Asia and the
youngest fossils found in other parts of the world. (which shows they originated in Africa and then
moved out of Africa, the youngest fossils are found where they were living most recent) .
Genetic Evidence:
• Geneticists use mitochondrial DNA (refer to diagrams below) to study human origins and migrations
since mtDNA is passed unchanged from mother to offspring. However, during a person’s life, mutations
(changes) to the mtDNA do occur.
• Scientists can determine the rate at which such mutations (or markers) take place, and can then use
them as a type of molecular clock to determine the age of a particular maternal mtDNA lineage.
• The most recent common female ancestor whose genetic marker is found in all living humans, must
have lived in eastern Africa approximately 150 000 years ago.
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Don’t confuse genetic evidence with fossil evidence!
8.1 Name the family to which all of the represented organisms belong. (1)
Remember: you need to know the family name of humans which is
Hominidae P
8.2 Describe how cultural evidence is used to support the theory of human
evolution. (2)
There are 3 types of evidence for human evolution namely fossil, genetic and cultural.
Cultural is all about the use of tools and how this indicate the development of thought.
Evidence such as tools/ weapons/language/artefactsP
Is used to show advancesP in human development
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How long ago did the most recent common ancestor of H. erectus and
8.3 H. heidelbergensis exist on earth?
The time is on the X-axis. Follow Homo erectus and Homo heidelbergensis lines back to (1)
where they both meet, if you extend down to the x axis it will be
3myaP
Explain a possible reason why H. ergaster was placed between A. afarensis and H.
8.4 heidelbergensis on the model. (2)
A fossil on a phylogenetic tree, placed in between two other fossils usually indicates a
transitional fossil. For 2 marks, you need to say it’s a transitional fossil and then explain what
that means.
H.ergaster shows characteristics of both H.heidelbergensis and A. afarensisP
Therefore, it’s a transitional speciesP
Explain how the fossils of organisms that existed from 4 mya to present
8.5 time are used to support the 'Out of Africa' hypothesis. (3)
This answer is stated “as is” in the exam guideline.
- The fossils of Australopithecus were ONLY found in AfricaP
- The fossils of Homo habilis were ONLY found in AfricaP
- The OLDEST fossils of Homo erectus were found in AfricaP
- The OLDEST fossils of Homo sapiens were found in AfricaP
- This suggests that the Homo sapiens originated in AfricaP*
*1 compulsory mark(the last bullet) because this state what the out of Africa hypothesis is
about and any 2 other bullets. Emphasis is on oldest and only. If they are not stated you
do not receive the mark.
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5. TYPICAL EXAM QUESTIONS
1 Fossils
2 Modification by descent (Homologous structures)
3 Biogeography
4 Genetics
A 1, 2 and 3 only
B 1, 2, 3 and 4
C 2, 3 and 4 only
D 1, 3 and 4 only
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1.5 The jaw of African Apes is…
A shorter and wider than humans
B has no spaces between the teeth
C has large sharp canines
D is flat and has a chin
1.6 THE GRAPH BELOW SHOWS THE COMPARISON OF DNA BETWEEN SPECIES A
AND SPECIES B, C, D AND E.
Which statement is a valid conclusion that can be drawn from this graph?
The diagram below shows Tiktaalik roseae, a fish that may be the ancestor of the first
organisms to live on land.
1.7
According to Lamarck, this species of fish may have evolved the ability to 'walk' on
land by …
A undergoing natural genetic mutations which caused the fins to develop into legs.
B the process of natural selection.
C passing on the acquired characteristic of fins to their offspring.
D stretching its fins and using them for 'walking'.
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Variation within a species is introduced through …
A random mating and asexual reproduction.
B mitosis and random fertilisation.
C random mating and random fertilisation
D mitosis and meiosis.
1.8 Which ONE of the following scientists discovered fossils of Homo sapiens and
Ardipithecus sp?
A Raymond Dart
B Lee Berger
C Louis Leakey
D Tim White
The diagram below compares characteristics of wild sunflowers with sunflowers that
1.9 have been artificially selected.
1.10
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1.11 Punctuated equilibrium suggests the following:
A Evolution is always a slow and gradual process.
B Natural selection does not explain evolution.
C New species can appear quickly, over a relatively short period
of time.
D Artificial selection is the only mechanism that causes evolution
1.12 A group of students observed that the long-term use of antibiotics results in the
decreased control of bacterial infections.
From this observation the students stated that:
Antibiotic resistance in bacteria is caused by the long-term use of antibiotics.
This statement is a/an …
A theory.
B aim.
C hypothesis
D conclusion. 12x2 =24
Give the correct biological term for each of the following descriptions. Write only the term
next to the question number (2.1 to 2.5) in your ANSWER BOOK.
2.1 Large, pointed teeth in African apes that are used for tearing food (1)
2.2 Organelle outside the nucleus of animal cells that contain DNA (1)
2.3 A large opening at the base of the skull through which the spinal cord passes (1)
2.4 An explanation of evolution that describes the speed at which it takes place (1)
2.5 The hypothesis which supports migration of human ancestors from the point of origin (1)
2.6 Similar structures in different organisms indicating descent with modification (1)
2.7 The part of the skull that houses the brain (1)
(8)
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QUESTION 3 (Questions taken from various sources)
Indicate whether each of the statements in COLUMN I applies to A ONLY, B ONLY, BOTH A
AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B, or none
next to the question number (3.1 to 3.4) in the ANSWER BOOK.
COLUMN I COLUMN II
3.1 A feature of Ardipithecus A: Opposable thumb
B: Stereoscopic vision
3.2 A diagram that is used to represent A: Phylogenetic tree
the evolutionary relationships and B: Cladogram
characteristics amongst different
species
(4 x 2) (6)
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4.1. Give the names of the TWO scientists that formulated this theory. (2)
4.2 Explain the trend observe in this graph. (4)
(6)
The diagram below shows the elongation of the neck of the giraffe according to Lamarck.
5.1 Use the example in the diagram to describe Lamarck’s theory for changes in the
(3)
giraffe’s neck over time.
5.2 Why was Lamarck’s theory rejected? (2)
(5)
When the Grand Canyon was formed, the population of the ancestral species of
squirrels living in the area was split into two sun-populations. Over a period two
species developed.
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One species is the Kaibab squirrel which has black fur and a fluffy tail. The other is
the Albert’s squirrel which has grey fur and a bushy tail.
Members of these two species have a similar size, shape, and diet, but they are no
longer in contact with each other and have become so different during their
separation that they are now separate species.
6.2 State TWO characteristics that distinguishes the two squirrel species from each
other. (2)
6.3 Describe how speciation of the two Grand Canyon squirrels took place through
geographic isolation. (6)
6.4 Name THREE reproductive isolating mechanisms that help to keep species
separate (3)
(13)
The diagram shows the upper jaw, scull and pelvic girdle of a modern human and an African
ape. The diagrams are NOT drawn to scale.
SKULL
ORGANISM UPPER JAW PELVIC GIRDLE
(BOTTOM VIEW)
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7.1 Which organism is bipedal? (1)
7.2 Use TWO visible features from the table above and explain your answer in
QUESTION 7.1.
(4)
7.3 Tabulate THREE visible differences between the upper jaws of organisms A and B.
(7)
7.4 Which organism is a African ape? (1)
(13)
Study the table below which shows evolutionary trends provided by the anatomical features
of fossils of different genera
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8.1 How many million years ago did Homo erectus first appear? (1)
8.2 Calculate the difference in brain volume between Australopithecus and Homo sapiens. (2)
Show ALL calculations.
8.4 Tabulate THREE visible differences between the skulls of Homo (7)
sapiens and the African ape. (13)
Brine shrimp are small arthropods found in saltwater lakes. During favourable conditions female
shrimps produce eggs that hatch into live young. However, when conditions are unfavourable, the
shrimp produce cysts. Each cyst contains the embryo covered with a hard, protective covering. In this
state the embryo stops growing and is said to be dormant. The embryo can remain in this dormant
state for many years and the cyst will only hatch at the optimum salt concentration.
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9.1 State TWO planning steps to consider before collecting the samples. (2)
9.3 Calculate the value of X in the table. Show ALL working. (3)
9.4 State THREE factors that were kept constant in order to ensure the (3)
validity of this investigation.
9.5 Use the theory of evolution through natural selection to explain (6)
(16)
10.1 Name the family to which all these species belong. (1)
10.2 What is the largest cranial capacity (in cm3) of Australopithecus africanus? (1)
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10.4 Name TWO Australopithecus fossils found in South Africa. (2)
10.5 Which of the organisms represented above has the greatest range in (1)
cranial capacity?
(6)
6. SOLUTIONS
QUESTION 1
1.1 DPP
1.2 BPP
1.3 DPP
1.4 APP
1.5 CPP
1.6 DPP
1.7 DPP
1.8 CPP
1.9 DPP
1.10 DPP
1.11 CPP
1.12 CPP 12 X 2 = (24)
QUESTION 2
2.1 CaniniesP
2.2 MitochondrionP
2.3 Foramen magnumP
2.4 Punctuated equilibriumP
2.5 Out of Africa hypothesisP
2.6 Homologous structuresP
2.7 CraniumP
2.8 PrognathousP (8)
QUESTION 3
3.1 Both A and B PP
3.2 A only PP
3.3 A only PP
3.4 A onlyPP (4x2) (8)
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QUESTION 4
4.1.1 EldredgeP
and GouldP (2)
4.1.2 Evolution sometimes involves long periodsP of time where species do not change/very
little change occursP (4)
This alternates with short periodsP of time where rapid changes occurP
(6)
QUESTION 5
5.1 All giraffes had short necks. P
These giraffes frequently stretched their necks.P
They did this to reach the leaves that were available only higher up the trees.P
As a result, their necks became longer. P
The characteristic for long necks acquired in this way was then passed on to the next
generation. P
Eventually all the giraffes had longer necks. P (Any 3)
(3)
5.2 There is no evidence Pto show that acquired characteristics are inherited P / There is no
evidence Pthat structures used more frequently became more developed or vice versaP /
a change in phenotype Pdoes not lead to a change in genotypeP
(2)
(5)
QUESTION 6
6.1 A population is a group of organisms of the same species found in the same habitat, that
can randomly interbreedPP (2)
6.2 - The colour of the fur coatP
- Type of tailP (2)
6.3 - The population of the Grand Canyon squirrels become split into two populationsP
- by a geographical barrier, a canyon*P.
- The two populations cannot interbreedP/there is no gene glow between the two.
- Natural selection occurs independently in each populationP
- due to different environmental conditions on either side of the barrierP
- The two populations become genotypically and phenotypicallyP
- differentP from each other.
- Even if the geographical barrier is removed, the individuals will not be able to
interbreed.P
- We say the original population has now become two separate species
(*Compulsory 1 + Any 5)
(6)
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6.4 Breeding at different times of the yearP
Species-specific courtship behaviourP
Adaptation to different pollinators P
Infertile offspringP
Prevention of fertilisationP (3)
(Mark first THREE only) (13)
QUESTION 7
7.1 AP (1)
7.2 Organism A has a short, broad/(wide and short)Ppelvis to support the upper body
weightP
And the foramen magnum is in a forward positionPto allow the spine to enter verticallyP (4)
7.3 TP
Homo sapiens (A) Primates (B)
Smaller caninesP Larger caninesP
Smaller spaces between the Larger spaces between the
teethP/No diastema teethP/diastema
Jaws with teeth on a gentle/round/C Jaws with teeth in a rectangular/U
curvedP shapeP
Not prognathousP PrognathousP (7)
(Mark first THREE only) 1 Table and (3 x 2)
7.4 BP (1)
(13)
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QUESTION 8
8.1 2 myaP (1)
(7)
QUESTION 9
= 1,8 P%
(3)
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9.4 - Room temperatureP
- The volume of solution usedP /30ml solution was used
- The amount of time P/ left the beakers for 48 hours
- Cysts from the same type of shrimpP
Any 3 (3)
(Mark first THREE only)
9.5 - There was variation Pamongst the brine shrimp
- Some had the ability to produce cystsP
- and some did not P
- When conditions became unfavourable P
- the brine shrimp which were unable to produce cysts died P
- Those which were able to produce cysts survived P
- and reproducedP
- The allele for producing cysts was passed on to
their offspringP
- The next generation therefore had a higher proportion of
brine shrimp with the ability to produce cystsP
Any 6 (6)
(16)
QUESTION 10
10.1 HominidaeP
(1)
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7. REFERENCES
1. DBE Examination Guidelines for learners
2. DBE Annual Teaching Plan
3. 2015-2020 NSC examination papers
4. 2014-2020 National Diagnostic Report on learner performance
5. DBE grade 12 textbook
6. Mind the Gap
7. Gauteng Grade 12 Life Sciences Revision booklet
8. Gauteng Grade 12 Life Sciences Exam kit
9. Internet
ACKNOWLEDGEMENT
The Department of Basic Education (DBE) gratefully acknowledges the following officials for giving up
their valuable time and families and for contributing their knowledge and expertise to develop this
resource booklet for the children of our country, under very stringent conditions of COVID-19:
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