SCSA Biology Science as a Human Endeavour
15 sample questions with marking guides and sample answers · Avg. score: 69%
Gene cloning has allowed the pharmaceutical industry to manufacture large quantities of proteins at a low cost. These proteins are produced by bacteria and are used to treat certain health conditions.
In the past, before the development of DNA technology, proteins for treating certain health conditions could be obtained only from animals, such as cattle and pigs, or from human corpses.
State two advantages of using gene cloning to manufacture pharmaceutical proteins rather than sourcing the proteins from animals or human corpses.
Reveal Answer
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Outline one ethical issue associated with the use of gene cloning in the manufacture of a pharmaceutical product.
Reveal Answer
For example: Changing a species' DNA may result in unforeseen consequences.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Discuss the ethical implications and impacts on society of the use of TWO biotechnologies.
Reveal Answer
A plant biotechnology that is of benefit to society is recombinant DNA technology eg when used to produce Bt corn or Bt cotton.
Recombinant DNA technology has many ethical implications. For example, Bt corn seeds cost money to purchase each season, while farmers using normal corn seeds can regrow their crops each year from their own seeds. This leads to inequalities in who has access to these GM seeds, and thus access to markets to sell their products.
The use of selective breeding/hybridisation is a type of biotechnology used in animals eg hybridisation of dairy cows to produce greater milk yielding cows. This has ethical implications for example, the side-effect of continuously selecting for greater milk yield has been a decrease in fertility amongst these cows, and may affect quality of life for cows.
However, there are also many benefits to society of the use of recombinant DNA technology or selective breeding/hybridisation. For example:
- the production of more food like Bt corn which can allow the human population to continue to grow, or greater milk availability for consumers in society
- greater yields for farmers, leading to increased profits and quality of life for farmers.
| Descriptor | Marks |
|---|---|
Provides an extensive discussion of the ethical implications and impacts for society of the use of two biotechnologies | 7 |
Provides a thorough discussion of the ethical implications and impacts for society of the use of two biotechnologies | 6 |
The student response meets all criteria of the 4-mark band, and additionally meets the majority of criteria in the 6-mark band. | 5 |
Provides a sound discussion of the ethical implication(s) and/or impact(s) for society of the use of biotechnology/biotechnologies | 4 |
The student response meets all criteria of the 2-mark band, and additionally meets the majority of criteria in the 4-mark band. | 3 |
Demonstrates some understanding of the ethical implication or benefit of the use of a biotechnology | 2 |
Provides some relevant information | 1 |
None of the above | 0 |
Scientists are investigating the mitochondrial genomes of different Aboriginal Australian populations. A purpose of these investigations is to reveal the pathways of migration of Aboriginal Australians who arrived from Sahul.
Mitochondrial DNA can be used for this purpose because it
contains genes that code for enzymes.
is always the same in specific populations.
is conserved through the maternal lineage.
is more structurally stable than nuclear DNA.
Reveal Answer
contains genes that code for enzymes.
While mitochondrial DNA does code for enzymes involved in cellular respiration, this functional characteristic does not help scientists trace historical migration pathways.
is always the same in specific populations.
Mitochondrial DNA is not identical within populations; in fact, the gradual accumulation of mutations over time creates distinct genetic markers (haplogroups) that scientists use to track migrations.
is conserved through the maternal lineage.
Mitochondrial DNA is inherited exclusively from the mother and does not undergo recombination, allowing scientists to trace unbroken maternal lineages back through time to map historical migrations.
is more structurally stable than nuclear DNA.
Mitochondrial DNA actually has a higher mutation rate than nuclear DNA due to its lack of protective histones and exposure to reactive oxygen species, so it is not more structurally stable.
The table provides population data for a species of fairy-wren.
| Year | Population on 1st January | Births | Deaths | Immigration | Emigration |
|---|---|---|---|---|---|
| 2022 | 15 200 | 7600 | 4310 | 790 | 24 |
The population growth rate in 2022 was closest to
17%
27%
55%
73%
Reveal Answer
17%
This value is incorrect. It results from miscalculating the net change or using the wrong denominator in the growth rate formula.
27%
The population growth rate is calculated as . Using the data: , which rounds to 27%.
55%
This calculation incorrectly considers only the population inputs (Births + Immigration) divided by the initial population (), failing to subtract deaths and emigration.
73%
This option is incorrect and likely represents the complement of the correct answer (), rather than the actual growth rate.
The following table provides information on three commonly grown genetically modified (GM) crops in Australia.
| Crop | Genetic modification | Characteristic given by modification |
|---|---|---|
| GM cotton | several bacterial genes inserted | insect resistance and herbicide tolerance |
| GM canola | two genes from two different bacterial species inserted | tolerance to several herbicides |
| GM safflower | a selection of genes silenced within the safflower genome | elevated levels of oleic acid in its seeds |
Select one of the GM crops in the table above and justify whether or not this crop could be described as transgenic.
Reveal Answer
An acceptable answer was one of the following:
- genetically modified (GM) cotton is transgenic as it contains genes from other species OR bacteria.
- GM canola is transgenic as it contains genes from other species OR bacteria.
- GM safflower is not transgenic as it does not contain genes from another species.
| Descriptor | Marks |
|---|---|
Provides a correct explanation of why the selected crop is or is not transgenic (e.g., GM cotton/canola is transgenic as it contains genes from other species/bacteria, OR GM safflower is not transgenic as it does not contain genes from another species) | 1 |
One issue with GM canola is the accidental release, during transport, of seeds along roadsides. Usually, unwanted plants that grow on the side of the road are killed using the herbicide glyphosate. However, GM canola is resistant to glyphosate.
Suggest one practical solution for treating GM canola that is found growing along roadsides.
Reveal Answer
An acceptable answer was one of the following:
- use a different herbicide that the GM canola is not resistant to
- remove by mowing
- pick the GM canola growing by the side of the road by hand
- use controlled burning.
| Descriptor | Marks |
|---|---|
Provides a correct practical solution to remove the GM canola (e.g., use a different herbicide, remove by mowing, pick by hand, use controlled burning) | 1 |
A new GM canola crop has been approved for use in Australia. It contains increased levels of omega-3 fatty acids, which are important, in humans, for building healthy cell membranes and for general growth and development, and also protect against a wide variety of diseases.
Omega-3 has traditionally been sourced from fish. Due to the growing demand for sources of omega-3, bioengineers have been encouraged to continue developing GM canola crops as a sustainable alternative.
Discuss one social implication and one biological implication of using GM canola with increased levels of omega-3. Use a different implication in each response.
Reveal Answer
Social implication
The correct answer was any one of the following:
- Farmers who grow non-GM canola may sell more canola and the farmer may have an improved quality of life OR may sell less canola and have a decreased quality of life.
- Improved nutrition for consumers and therefore less demand on the health system.
- More people have access to better nutrition as GM canola is cheaper OR more accessible than fish.
- There could be a decreased consumption of fish, which results in fish farmers making less money and having a lower quality of life.
- Consumers may not want to consume GM food. This could lead to consumers not buying enough GM canola and farmers having a lower quality of life.
Biological implication
Accepted responses included any one of the following:
- Possible crossbreeding with non-GM canola crops leading to a change in genome of the crops.
- Potential lack of genetic variation within the GM canola crop. All GM canola plants could then die if there is a change in a selection pressure.
- Consumers may not want to eat or purchase any GM products as these consumers are concerned it is not safe to eat.
- Less fish consumed reduces overfishing, leading to an increase in the fish population.
- Improved nutrition for consumers improves health outcomes for consumers.
Social Implication
| Descriptor | Marks |
|---|---|
Identifies a valid social implication (e.g., economic impact on farmers, improved nutrition for consumers, access to cheaper nutrition) | 1 |
Explains the social implication (e.g., improved/decreased quality of life, less demand on the health system) | 1 |
Biological Implication
| Descriptor | Marks |
|---|---|
Identifies a valid biological implication (e.g., crossbreeding with non-GM crops, lack of genetic variation, impact on fish populations, health outcomes) | 1 |
Explains the biological implication (e.g., change in genome, susceptibility to selection pressures, reduces overfishing, improves health) | 1 |
'Super weeds' are most likely to emerge via
a novel mutation in a weed species.
gene flow from a transgenic crop to a weed species.
natural selection in a weed population.
artificial selection in a weed population.
Reveal Answer
a novel mutation in a weed species.
While a novel mutation could confer herbicide resistance, it is a slow and rare process compared to the rapid acquisition of engineered resistance genes via cross-pollination.
gene flow from a transgenic crop to a weed species.
"Super weeds" often emerge when herbicide-resistance genes from transgenic crops are transferred to closely related wild weed species through gene flow, making them highly resistant to standard weed-control methods.
natural selection in a weed population.
Although natural selection drives the spread of resistant traits once they exist, the sudden emergence of "super weeds" with engineered traits is primarily initiated by gene flow from transgenic crops.
artificial selection in a weed population.
Artificial selection is the intentional breeding of organisms by humans for desirable traits, which does not apply to the unintentional emergence of resistant weeds.
The application of computers and statistics to manage and interpret large biological data sets is called
bioinformatics.
biochemistry.
biotechnology.
comparative genomics.
Reveal Answer
bioinformatics.
Bioinformatics is the interdisciplinary field that combines computer science, statistics, and mathematics to analyze and interpret complex biological data.
biochemistry.
Biochemistry focuses on the chemical processes and substances occurring within living organisms, rather than computational data analysis.
biotechnology.
Biotechnology is the use of living systems or organisms to develop or create products, not the computational management of biological data.
comparative genomics.
Comparative genomics is a specific subfield that compares the genomes of different species, whereas bioinformatics is the broader computational toolset used to perform this analysis.
In some parts of Australia, duck hunting is allowed but only during the duck season, which lasts for about 30 days per year. Information on which of the following is crucial for ensuring that duck season is timed so that hunting will have a minimal impact on the duck populations?
number of duck populations
gene pool of duck populations
reproductive biology of ducks
abundance of duck predators
Reveal Answer
number of duck populations
The total number of duck populations does not provide the seasonal life cycle information needed to determine the best time of year for a hunting season.
gene pool of duck populations
While the gene pool is important for long-term genetic health, it does not fluctuate seasonally in a way that would dictate the timing of a hunting season.
reproductive biology of ducks
Understanding the reproductive biology, such as mating and nesting seasons, allows wildlife managers to schedule hunting when it will least disrupt reproduction and population growth.
abundance of duck predators
Predator abundance might affect overall survival rates, but it does not provide the seasonal life history information required to properly time a hunting season.
Genetically modified (GM) crops are engineered to introduce a new trait into a species. Traits chosen by scientists are ones that will benefit people either directly or indirectly.
An example of such a trait is one that
decreases the nutritional value of a crop.
improves environmental conditions for crops.
increases resistance to toxins produced by fungi.
develops potential allergens that trigger a vigorous immune response.
Reveal Answer
decreases the nutritional value of a crop.
Decreasing the nutritional value of a crop would be harmful to consumers, whereas GM crops are typically engineered to increase or maintain nutritional value.
improves environmental conditions for crops.
Genetic modification alters the biological traits of the crop itself, such as drought tolerance, rather than changing the external environmental conditions.
increases resistance to toxins produced by fungi.
Engineering crops to resist fungal toxins protects the plant from disease and prevents harmful toxins from entering the human food supply, providing a clear agricultural and health benefit.
develops potential allergens that trigger a vigorous immune response.
Introducing new allergens would cause adverse health effects in humans, which contradicts the goal of engineering traits that benefit people.
PAI-1 protein is encoded by the SERPINE 1 gene in humans. Anopheles mosquitoes have been genetically modified to express PAI-1, which blocks the entry of the malarial Plasmodium into the mosquito gut. This disrupts the Plasmodium life cycle, resulting in reduced transmission of malaria.
Describe a process that could be used to produce mosquitoes which express PAI-1.
Reveal Answer
To produce the genetically modified (GM) mosquitoes, it is necessary to transfer the SERPINE 1 gene from a human to the mosquito using recombinant DNA technology. Restriction enzymes are used to cut the SERPINE 1 gene from a human cell chromosome. A bacterial plasmid (circular DNA) is opened using the same restriction enzymes and the SERPINE 1 gene is inserted and attached using DNA ligase. The bacteria then reproduce, producing multiple copies of the SERPINE 1 gene. The gene can then be delivered into the mosquitos. This can be done by micro-injection into mosquito egg cells, so that the mosquito which develop from the egg will contain the SERPINE 1 gene, which will allow the mosquito to express PAI-1.
| Descriptor | Marks |
|---|---|
Describes an appropriate process used to produce genetically modified mosquitoes | 4 |
Outlines an appropriate process used to produce genetically modified mosquitoes | 3 |
Shows some understanding of how genetically modified mosquitoes are produced | 2 |
Provides some relevant information | 1 |
None of the above | 0 |
'Genetic technologies are beneficial for society.'
Evaluate this statement.
Reveal Answer
In recombinant DNA technology, selected genes can be cut and pasted from one organism into another using, for example, ligase enzymes. The human insulin producing gene has been transferred into bacteria, allowing for increased production of insulin, benefitting sufferers of diabetes, who can access insulin more readily and cheaply. This means that diabetes patients have a greater life span.
Genetic technologies such as CRISPR can be used for controlling pest populations including insects that cause diseases in both humans and other animals. By controlling the number of disease causing insects eg mosquitoes that cause dengue fever, we can significantly reduce the incidence of the vector-borne diseases. This would result in healthier populations and reduced stress on the health care system.
These technologies have largely been beneficial to society, improving access to drugs, the life expectancy and quality of life for many people.
| Descriptor | Marks |
|---|---|
| 7 |
| 6 |
The student response meets all criteria of the 4-mark band, and additionally meets the majority of criteria in the 6-mark band. | 5 |
| 4 |
The student response meets all criteria of the 2-mark band, and additionally meets the majority of criteria in the 4-mark band. | 3 |
| 2 |
| 1 |
None of the above | 0 |
Until May 2019, Denisovan fossils had been found in only two locations: Siberia and Tibet. Since then, Denisovan DNA has been discovered in some present-day populations. These populations are found on several continents, including Australia.
This suggests that the ancient Denisovan hominin group was or its descendants were
only fossilised in Siberia and Tibet.
genetically identical to Homo sapiens.
extinct prior to the presence of Neanderthals.
more widespread than fossil evidence suggests.
Reveal Answer
only fossilised in Siberia and Tibet.
While fossils have only been found in Siberia and Tibet so far, the presence of their DNA in modern populations across multiple continents suggests they likely lived and died elsewhere too.
genetically identical to Homo sapiens.
If they were genetically identical to Homo sapiens, scientists would not be able to distinguish distinct Denisovan DNA in present-day populations.
extinct prior to the presence of Neanderthals.
The prompt provides no information about Neanderthals, and the presence of Denisovan DNA in modern humans indicates they survived long enough to interbreed with our ancestors.
more widespread than fossil evidence suggests.
The discovery of Denisovan DNA in modern populations across several continents indicates that Denisovans or their descendants migrated far beyond the two locations where their fossils have currently been found.
Biogeography can contribute to the design of a protected area for conservation by
optimising the location of the area based on species' distributions.
predicting which species in the area are most likely to go extinct.
determining the population dynamics of species in the area.
documenting the reproductive biology of species using the area.
Reveal Answer
optimising the location of the area based on species' distributions.
Biogeography is the study of the geographic distribution of species. This spatial knowledge is essential for placing protected areas where they will conserve the most biodiversity or protect specific target species.
predicting which species in the area are most likely to go extinct.
Predicting extinction risk is typically the focus of population viability analysis and conservation biology, rather than the spatial focus of biogeography.
determining the population dynamics of species in the area.
Determining population dynamics, such as birth and death rates over time, falls under population ecology rather than biogeography.
documenting the reproductive biology of species using the area.
Documenting reproductive biology is a focus of reproductive ecology or life history studies, which does not directly address the spatial distribution of species studied in biogeography.
Tasmanian devils (Sarcophilus harrisii) were originally broadly distributed across Australia. When sea levels rose 12 000 years ago, an island, now referred to as Tasmania, was formed. The small number of Tasmanian devils on Tasmania was cut off from the Australian mainland populations. The population in Tasmania showed less genetic variation than the mainland populations. Mainland populations became extinct approximately 3000 years ago.
Over the last 20 years, the total Tasmanian devil population on Tasmania has halved. Many of the deaths have been the result of Tasmanian devil facial tumour disease (DFTD). Scientists have taken some Tasmanian devils that do not have DFTD to mainland Australia to set up a conservation program. The scientists have shown that greater genetic diversity among offspring in this program is observed when the Tasmanian devils are kept in isolated male–female pairs rather than in larger groups.
The conservation program for Tasmanian devils is an example of
a population bottleneck.
allopatric speciation.
selective breeding.
natural selection.
Reveal Answer
a population bottleneck.
A population bottleneck refers to a sharp reduction in population size, which happened to the wild Tasmanian devils due to disease and isolation. However, the conservation program itself is an effort to recover the population, not a bottleneck.
allopatric speciation.
Allopatric speciation is the evolution of a new species due to geographic isolation. The goal of this conservation program is to preserve the existing species, not to create a new one.
selective breeding.
The scientists are intentionally selecting specific individuals (those without DFTD) and controlling their mating (using isolated male-female pairs) to achieve a desired outcome (greater genetic diversity). This human-directed mating is the definition of selective breeding.
natural selection.
Natural selection is driven by environmental pressures without human intervention. Because scientists are actively choosing which individuals breed and how they are paired, this is an example of artificial selection, not natural selection.
The Montara oil spill, which occurred off the northwest coast of Western Australia in August 2009, is classed as one of the worse oil disasters in Australian waters. Oil spills are initially treated with detergents (to disperse the spill) and fire, but genetically-modified bacteria that can digest the oil are sometimes also used.
Describe how recombinant DNA technology is used to genetically modify bacteria to digest oil and discuss two advantages and two disadvantages of using a genetically-modified microorganism for environmental conservation.
Reveal Answer
To genetically modify bacteria using recombinant DNA technology, first isolate a suitable gene, which must be a gene that produces an enzyme that digests oil. Choose a suitable bacterium for genetic modification (one that can survive in aquatic environments). Use the same restriction enzyme to remove the gene from the host and insert it into a plasmid. Amplify the target gene in the plasmid or by polymerase chain reaction (PCR), and insert the gene into the target bacteria. Transform the bacteria using heat shock, and check the ability of the bacteria to reproduce and produce the gene product.
The advantages of this use include the ability to use genes from other species to achieve outcomes not possible via natural processes. After development, it is easy and fast to produce and supply transgenics in large quantities; and microorganisms are easy to transport, handle, and store.
However, disadvantages include that transgenic organisms could have a negative impact on other organisms or the environment, such as oil-digesting bacteria taking over and displacing natural bacteria. There is also the risk of gene transfer to other organisms.
Description of recombinant DNA technology used to genetically modify bacteria
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 6 of):
| 6 |
Advantages of use
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Disadvantages of use
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Gene pools are dynamic, with changes in allele frequencies being caused by several factors, including mutation and genetic drift.
Describe how mutation and genetic drift change the frequency of alleles in a population and explain the significance of these changes.
Reveal Answer
A mutation is a permanent change to DNA that occurs at random. It changes one allele to another or creates new alleles.
The significance of changes made by mutation is that they can have deleterious effects on individuals. Mutations have a limited effect on allele frequencies because the rate of mutation is low, but they are the source of all genetic variation, alleles, and biological diversity. Other evolutionary processes are dependent on this variation, and populations cannot evolve without genetic variation.
Genetic drift involves the random death of individuals, leading to random or chance changes in allele frequencies. It has the biggest effect in small populations.
The significance of changes made by genetic drift is that it can result in the loss of advantageous alleles. This places populations at risk of extinction due to an inability to adapt.
Mutation
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Significance of changes made by mutation
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 3 of):
| 3 |
Genetic drift
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Significance of changes made by genetic drift
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 3 of):
| 3 |
Fleece colour in sheep is determined by the alleles at an autosomal gene, where a dominant
allele (T) gives white fleece, and a recessive allele (t) gives black fleece.
Two white sheep are mated. They produce offspring with white fleece and with black fleece.
Distinguish between a dominant and a recessive allele.
Reveal Answer
Dominant – only one copy of allele is needed for an individual to show phenotype.
Recessive – two copies of allele are needed for an individual to show phenotype or only recessive homozygote will show phenotype.
| Descriptor | Marks |
|---|---|
dominant – only one copy of allele is needed for an individual to show phenotype or heterozygote will show phenotype | 1 |
recessive – two copies of allele are needed for an individual to show phenotype or only recessive homozygote will show phenotype or can be masked by a dominant allele | 1 |
Distinguish between autosomal and sex-linked alleles.
Reveal Answer
Autosomal – alleles are on autosomal chromosomes.
Sex linked – alleles are on sex chromosomes.
| Descriptor | Marks |
|---|---|
autosomal – alleles are on autosomal chromosomes or alleles are not on sex chromosomes or two alleles are present in both males and females | 1 |
sex linked – alleles are on sex chromosomes or X/Y chromosome or two alleles are present in females and only one is present in males | 1 |
Calculate the probability of these sheep producing an offspring with black fleece. Explain
your answer.
Reveal Answer
0.25.
Both parents must be heterozygotes.
Black offspring must have tt genotype (because black fleece is recessive).
Only one in four offspring will have tt genotype.
| Descriptor | Marks |
|---|---|
0.25/25%/1 in 4 | 1 |
Both parents must be heterozygotes or Tt (to produce black sheep) or both will produce gametes with T and with t allele (in equal proportions) | 1 |
Must use specified notation for alleles (T,t). | 1 |
Black offspring must have tt genotype (because black fleece is recessive). | 1 |
Only one in four offspring will have tt genotype or three in four offspring will have one copy of T/dominant allele. | 1 |
Spider lamb syndrome (SLS) is an inherited condition in sheep. Affected animals have
abnormal spines and long, often splayed (spread out) legs. SLS is caused by a recessive
SLS allele at an autosomal gene. Outline an approach that can be used to determine
whether an unaffected individual has the SLS allele without breeding the sheep.
Reveal Answer
DNA sequencing can determine nucleotide sequence to compare genomes.
Any 2 of:
- take samples from affected and unaffected sheep
- extract DNA
- use PCR/restriction enzymes/gel electrophoresis
| Descriptor | Marks |
|---|---|
DNA sequencing or (comparative) genomics | 1 |
determine nucleotide sequence | 1 |
compare genomes/DNA sequences of affected and unaffected sheep | 1 |
1 mark for each correct point (any 2 of):
| 2 |
Body size in sheep is a polygenic trait. Explain what a polygenic trait is.
Reveal Answer
Controlled by the alleles at many genes, and also influenced by the environment.
Trait shows many different phenotypes in a population.
| Descriptor | Marks |
|---|---|
controlled/influenced by the alleles at many genes/by many genes | 1 |
also influenced by the environment | 1 |
trait shows many different phenotypes in a population or trait shows continuous variation/a normal distribution in a population | 1 |
A group of biologists want to produce a line of sheep with increased resistance to fleece
rot. They could do this either by artificial selection or by transgenesis. Outline one
advantage and one disadvantage of producing this line of sheep by artificial selection
rather than transgenesis.
Reveal Answer
Advantage
- (breeding sheep is a) natural process
- can be done on farm/does not require specialist equipment/less controversial
Disadvantage
- artificial selection changes allele/gene frequencies gradually
- slower process or will take many generations to produce desired line
Advantage
| Descriptor | Marks |
|---|---|
(breeding sheep is a) natural process | 1 |
can be done on farm/does not require specialist equipment/less controversial | 1 |
Disadvantage
| Descriptor | Marks |
|---|---|
artificial selection changes allele/gene frequencies gradually | 1 |
slower process or will take many generations to produce desired line | 1 |