NESA Biology Inheritance Patterns in a Population
15 sample questions with marking guides and sample answers · Avg. score: 73.1%
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.
Koalas were once widespread in Australia. Due to a variety of factors, their population decreased and fragmented into small pockets, forcing them to inbreed. They have recently been hit by devastating epidemic diseases.
Explain why koalas face an increased extinction risk from disease.
Reveal Answer
High genetic diversity may allow for some members of the population to survive diseases and later reproduce and pass on their resistance to increase the survivability of the population.
However, inbreeding creates low genetic diversity, which makes koalas vulnerable to extinction due to disease.
| Descriptor | Marks |
|---|---|
Explains how genetic diversity can prevent extinction during rapid environmental change, e.g. disease | 1 |
Describes why koalas have low genetic diversity (inbreeding) | 1 |
States that koalas are more vulnerable to extinction due to low genetic diversity | 1 |
DNA profiling is used to
measure gene expression.
quantify gene flow.
identify individuals and species.
create transgenic organisms.
Reveal Answer
measure gene expression.
Incorrect. Measuring gene expression involves analyzing RNA levels using techniques like RT-qPCR or RNA sequencing, whereas DNA profiling looks at the DNA sequence itself.
quantify gene flow.
Incorrect. While genetic markers can be used in population genetics, DNA profiling specifically focuses on identifying unique genetic patterns of individuals rather than tracking the movement of alleles between populations.
identify individuals and species.
Correct. DNA profiling, also known as DNA fingerprinting, analyzes highly variable regions of the genome to uniquely identify individuals or distinguish between species.
create transgenic organisms.
Incorrect. Creating transgenic organisms requires recombinant DNA technology and genetic engineering to insert foreign genes, which is entirely different from analyzing existing DNA profiles.
Polymerase chain reaction (PCR), gel electrophoresis and DNA sequencing are biotechnological processes that can be used to help provide evidence for evolution.
Contrast PCR and gel electrophoresis in terms of the purpose, processes and end products formed.
Reveal Answer
The purpose of PCR is to create more copies of a DNA sequence, whereas gel electrophoresis is used to separate DNA strands based on size.
In terms of process, PCR uses a thermal cycle while gel electrophoresis uses an electric current in an agarose gel. Also, PCR uses enzymes to copy DNA, while gel electrophoresis uses enzymes to break DNA into fragments.
For the end products, PCR creates large amounts of copied DNA, whereas gel electrophoresis provides a visual representation of DNA fragments.
| Descriptor | Marks |
|---|---|
States that the purpose of PCR is to amplify or create more copies of a DNA sequence | 1 |
States that the purpose of gel electrophoresis is to separate DNA strands based on size | 1 |
Contrasts the processes by stating that PCR uses a thermal cycle, repeated cycles, or a thermocycler (1 mark), while gel electrophoresis uses an electric current in an agarose gel (1 mark) | 2 |
Contrasts the processes by stating that PCR starts with a small amount of DNA (1 mark), while gel electrophoresis starts with a large amount of DNA (1 mark) | 2 |
Contrasts the processes by stating that PCR uses enzymes to copy DNA (1 mark), while gel electrophoresis uses enzymes to break DNA into fragments (1 mark) | 2 |
States that the end product of PCR is large amounts of copied DNA | 1 |
States that the end product of gel electrophoresis is DNA bands or a visual representation of DNA fragments | 1 |
Define the term 'DNA sequencing' and identify five ways in which DNA sequencing can be used to provide evidence for evolution.
Reveal Answer
DNA sequencing determines the order of nucleic acids in the DNA.
It is used to (any 5 of the following):
- identify the degree of genetic variations in a population
- identify the degree of genetic similarity between species
- quantify the degree of genetic diversity between species
- establish molecular clocks or determine the time since organisms shared a common ancestor
- help construct phylogenetic trees
- identify how genes derived from common ancestors have changed over time
- and use comparative genomics to help understand the process of evolutionary changes over time.
| Descriptor | Marks |
|---|---|
Explains that DNA sequencing determines the order of nucleic acids in the DNA | 1 |
1 mark for each correct point (any 5 of):
| 5 |
Explain how the process of bioinformatics can be applied to help determine the relatedness of species.
Reveal Answer
Bioinformatics allows for large scale computerised analysis of genetic data. This allows the determination of the degree of similarity. The higher the degree of similarity, the more recent the separation from a common ancestor, which helps determine where species are placed in phylogenetic trees.
| Descriptor | Marks |
|---|---|
States that it allows for large scale computerised or mathematical analysis of biological or genetic data | 1 |
Explains that it allows the determination of the degree of similarity | 1 |
States that the higher the degree of similarity, the more recent the separation from a common ancestor | 1 |
Concludes that it helps determine where species are placed in phylogenetic trees or evolutionary models of relationships between species | 1 |
Polymerase chain reaction is a technique used in DNA profiling to
cut DNA at specific sites.
create more copies of DNA.
determine the order of nucleotides.
separate DNA fragments based on size.
Reveal Answer
cut DNA at specific sites.
Cutting DNA at specific sites is the function of restriction enzymes (endonucleases), not PCR.
create more copies of DNA.
The primary purpose of Polymerase Chain Reaction (PCR) is to amplify specific DNA sequences, creating millions of copies from a small initial sample.
determine the order of nucleotides.
Determining the specific order of nucleotides is the goal of DNA sequencing, whereas PCR is used only for amplification.
separate DNA fragments based on size.
Separating DNA fragments based on size is achieved through gel electrophoresis, not PCR.
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.
Explain the purpose of the polymerase chain reaction (PCR) process and provide an example of its application.
Reveal Answer
Polymerase chain reaction is used to amplify (i.e. make many copies) of a DNA template because usually only a small amount of DNA is available for analysis.
For example, crime scene DNA is sometimes found only at trace levels. PCR amplifies this small amount to allow analysis to be carried out.
| Descriptor | Marks |
|---|---|
Explains purpose of PCR as amplifying a DNA sample for further analysis | 1 |
Provides an example | 1 |
An evolutionary biologist used several methods to construct a phylogenetic tree for a group of mammals.
Which one of these methods would have been least useful?
amino acid sequences
protein sequences
bone structure
presence of hair
Reveal Answer
amino acid sequences
Amino acid sequences accumulate mutations over time, making them highly useful for comparing genetic divergence and determining evolutionary relationships among different mammals.
protein sequences
Protein sequences provide valuable molecular data for constructing phylogenetic trees, as comparing their similarities and differences helps identify how closely related different species are.
bone structure
Variations in bone structure (homologous structures) provide important morphological evidence that helps biologists distinguish and group different mammalian lineages.
presence of hair
Because the presence of hair is a defining characteristic shared by all mammals, it offers no variation to help differentiate or determine evolutionary relationships within the group.
Polymerase chain reaction (PCR) is a laboratory procedure used in DNA sequencing. PCR mimics cellular
DNA replication.
DNA repair.
transcription.
translation.
Reveal Answer
DNA replication.
Correct. PCR is an in vitro technique used to amplify specific DNA segments, directly mimicking the cellular process of DNA replication where a cell copies its genetic material.
DNA repair.
Incorrect. DNA repair involves identifying and fixing damaged DNA strands, whereas PCR is designed to synthesize new copies of a DNA template rather than fix errors.
transcription.
Incorrect. Transcription is the cellular process of synthesizing RNA from a DNA template, while PCR synthesizes new DNA strands.
translation.
Incorrect. Translation is the process of building proteins from an mRNA template at the ribosome, which is entirely different from the DNA amplification performed in PCR.
Neanderthals and early Homo sapiens share a common ancestor that originated in Africa. By the time modern humans left Africa around 300 000 years ago, Neanderthals had been living in Europe and Asia for approximately 100 000 years.
Early genetic studies identified around 0.02% of Neanderthal DNA in genomes of modern Africans. New research has identified that those with African ancestry have closer to 0.5% Neanderthal DNA. The same study found that Neanderthal DNA contributed 1.7% to European genomes and 1.8% in Asian genomes.
Suggest two possible ways in which people with African ancestry could have some Neanderthal DNA in their genomes.
Reveal Answer
Possible ways that people with African ancestry could have Neanderthal DNA in their genomes included:
- Ancestors of modern Africans could have interbred with Neanderthals before migrating from Africa.
- Ancestors of modern Africans left Africa and interbred with Neanderthals already in Europe and Asia, before returning to Africa.
- Modern-day Africans still carry Neanderthal DNA that was shared DNA from their common ancestor.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Suggest why it is reasonable that modern Europeans and Asians show greater percentages of Neanderthal DNA than people who originated in Africa.
Reveal Answer
Possible reasons why modern Europeans and Asians show a greater percentage of Neanderthal DNA included:
- Homo sapiens coexisted with Neanderthals for a longer period of time in Europe and Asia, so more opportunities existed for interbreeding.
- Homo sapiens who originated in Africa did not coexist or interbreed with Neanderthals, as Neanderthals did not live in Africa.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Electrophoresis separates DNA fragments based on
size, with larger fragments travelling further through the gel.
size, with smaller fragments travelling further through the gel.
charge, with more positively charged fragments travelling further through the gel.
charge, with more negatively charged fragments travelling further through the gel.
Reveal Answer
size, with larger fragments travelling further through the gel.
This is incorrect because larger DNA fragments encounter more resistance from the gel matrix, causing them to migrate slower and travel a shorter distance than smaller fragments.
size, with smaller fragments travelling further through the gel.
The gel acts as a molecular sieve where smaller DNA fragments can pass through the pores more easily, allowing them to migrate faster and travel further towards the positive electrode.
charge, with more positively charged fragments travelling further through the gel.
DNA is negatively charged due to its phosphate backbone, not positively charged, and therefore migrates toward the positive electrode (anode).
charge, with more negatively charged fragments travelling further through the gel.
While DNA is negatively charged, the charge-to-mass ratio is constant for DNA fragments; therefore, separation is determined by the physical resistance (size) rather than differences in charge intensity.
Listed below is a series of characteristics found within the primate group.
I. reduction in olfactory centre of brain
II. non-opposable big toe
III. bipedal gait
IV. flat face
V. pentadactyl limb
Which combination of characteristics makes a hominin different from all other primates?
I and III only
II and III only
III, IV and V
I, III and IV
Reveal Answer
I and III only
While hominins do have a bipedal gait (III), a reduction in the olfactory centre of the brain (I) is a characteristic shared by many other primates, such as monkeys and apes, so it does not distinguish hominins.
II and III only
Hominins are uniquely defined among primates by their bipedal gait (III) and the associated skeletal adaptation of a non-opposable big toe (II) which provides thrust during upright walking.
III, IV and V
A pentadactyl (five-digit) limb (V) is a primitive trait found in all primates and most tetrapods, meaning it cannot be used to differentiate hominins from other primates.
I, III and IV
A reduction in the olfactory centre (I) and a relatively flat face (IV) are evolutionary trends seen across various primate lineages, not just hominins, making this combination incorrect.
In a polymerase chain reaction, the process by which new nucleotides are added is
known as
priming.
denaturation.
extension.
annealing.
Reveal Answer
priming.
Incorrect. While primers are required to start the process, the actual addition of new nucleotides to build the full DNA strand is not called priming.
denaturation.
Incorrect. Denaturation is the first step of PCR, where high heat is used to break hydrogen bonds and separate the double-stranded DNA into single strands.
extension.
Correct. Extension, or elongation, is the step where DNA polymerase (like Taq polymerase) adds free nucleotides to the 3' end of the primer to synthesize the new complementary DNA strand.
annealing.
Incorrect. Annealing is the second step of PCR, where the temperature is lowered to allow short DNA primers to bind to the single-stranded template before new nucleotides are added.
Comparative genomics refers to research in which
the complete DNA sequence of an organism is compared to one of another species.
computerised data on the molecular structure of the genome of a species is analysed.
chromosomes are extracted and gene sequences of a species are mapped.
proteins, RNA and DNA of one species are compared to that of another species.
Reveal Answer
the complete DNA sequence of an organism is compared to one of another species.
Comparative genomics specifically involves comparing the complete genome (DNA sequences) of different species to understand evolutionary relationships and gene function.
computerised data on the molecular structure of the genome of a species is analysed.
Analyzing computerized genomic data of a single species describes bioinformatics or structural genomics, missing the essential comparison between different species.
chromosomes are extracted and gene sequences of a species are mapped.
Extracting chromosomes and mapping gene sequences refers to genome mapping, which does not inherently involve comparing genomes across different species.
proteins, RNA and DNA of one species are compared to that of another species.
Comparative genomics focuses exclusively on comparing genomes (DNA). Comparing proteins falls under proteomics, and comparing RNA falls under transcriptomics.
A small sample of DNA was obtained from a fossil. Polymerase chain reaction (PCR) was used to amplify the amount of DNA obtained from the sample.
Which one of the following is a correct statement regarding the PCR process?
DNA polymerase catalyses the pairing of primers with complementary nucleotides.
RNA polymerase catalyses the additions of nucleotides to a DNA strand.
Annealing and extension of the DNA occur at different temperatures.
The number of copies of the DNA is quadrupled in each cycle.
Reveal Answer
DNA polymerase catalyses the pairing of primers with complementary nucleotides.
Primers bind to the template DNA via hydrogen bonding during the annealing phase, which does not require an enzyme. DNA polymerase instead catalyzes the addition of free nucleotides to the primer during the extension phase.
RNA polymerase catalyses the additions of nucleotides to a DNA strand.
PCR utilizes a heat-stable DNA polymerase, such as Taq polymerase, to synthesize new DNA strands. RNA polymerase is used during transcription to synthesize RNA, not in PCR.
Annealing and extension of the DNA occur at different temperatures.
The annealing phase requires a cooler temperature (typically ) for primers to bind, whereas the extension phase requires a warmer temperature (around ) for optimal DNA polymerase activity.
The number of copies of the DNA is quadrupled in each cycle.
The amount of DNA doubles during each cycle of PCR, following exponential growth (), rather than quadrupling.