NESA Biology Reproduction
15 sample questions with marking guides and sample answers · Avg. score: 68.8%
What is a key difference between spermatogenesis and oogenesis?
Spermatogenesis produces haploid cells, whereas oogenesis produces diploid cells.
Spermatogenesis produces four functional gametes, whereas oogenesis produces one.
Spermatogenesis occurs throughout life, whereas oogenesis only occurs after puberty.
Spermatogenesis begins with haploid cells, whereas oogenesis begins with diploid cells.
Reveal Answer
Spermatogenesis produces haploid cells, whereas oogenesis produces diploid cells.
Both spermatogenesis and oogenesis are forms of meiosis that result in the production of haploid gametes () from diploid germ cells ().
Spermatogenesis produces four functional gametes, whereas oogenesis produces one.
Spermatogenesis results in four equally sized, functional sperm cells, whereas oogenesis involves unequal cytokinesis, producing one large functional ovum and smaller, non-functional polar bodies.
Spermatogenesis occurs throughout life, whereas oogenesis only occurs after puberty.
Spermatogenesis begins at puberty and continues throughout life, whereas oogenesis begins during fetal development, arrests, and resumes at puberty.
Spermatogenesis begins with haploid cells, whereas oogenesis begins with diploid cells.
Both processes begin with diploid stem cells (spermatogonia and oogonia) that differentiate into diploid primary spermatocytes and oocytes before undergoing meiosis.
Prior to modern human pregnancy test kits, Xenopus frogs were used. Urine samples from women were injected into the legs of female frogs. The frogs were then placed back into water tanks and, the following day, the tanks were checked for eggs. If a female frog had laid eggs, the woman who had provided the urine sample was diagnosed to be pregnant.
Which one of the following factors may result in a false diagnosis of pregnancy?
using male frogs instead of female frogs
maintaining an optimum tank temperature
replacing the water in the tanks with fresh water each day
female frogs laying eggs naturally around the time of the injection
Reveal Answer
using male frogs instead of female frogs
Male frogs cannot lay eggs, so using them would result in a false negative (no eggs laid), rather than a false positive diagnosis of pregnancy.
maintaining an optimum tank temperature
Maintaining an optimum temperature is a standard procedure to keep the frogs healthy and capable of responding to the hormone; it does not spontaneously induce egg-laying.
replacing the water in the tanks with fresh water each day
Replacing the water is a standard husbandry practice to maintain a clean environment and would not trigger spontaneous egg-laying.
female frogs laying eggs naturally around the time of the injection
If a frog lays eggs naturally, it would appear as a positive test result even if the woman's urine did not contain pregnancy hormones, leading to a false positive diagnosis.
Cabbage, cauliflower, broccoli and kale are some of the oldest known vegetables. They descended from the wild mustard plant Brassica oleracea, which humans began planting thousands of years ago. These vegetables were developed by
natural selection.
artificial selection.
transgenesis.
mutagenesis.
Reveal Answer
natural selection.
Natural selection is driven by environmental pressures, whereas these vegetables were developed through human intervention and preference.
artificial selection.
Artificial selection, or selective breeding, occurs when humans intentionally breed plants or animals for specific desirable traits, which is how these vegetables were developed from wild mustard.
transgenesis.
Transgenesis involves introducing genetic material from one species into another using modern genetic engineering, a technology that did not exist thousands of years ago.
mutagenesis.
Mutagenesis is the process of inducing mutations using chemicals or radiation, which was not the method used by early farmers to develop these crops.
Which of the following processes creates genetic variation in bacteria?
binary fission
crossing over
mutation
natural selection
Reveal Answer
binary fission
Incorrect. Binary fission is a form of asexual reproduction that produces genetically identical clones, meaning it does not create new genetic variation.
crossing over
Incorrect. Crossing over is a process that creates genetic variation during meiosis in eukaryotes, but bacteria do not undergo meiosis.
mutation
Correct. Mutations are random changes in the DNA sequence and serve as the primary source of new genetic variation in bacteria.
natural selection
Incorrect. Natural selection acts upon existing genetic variation to determine which traits survive and reproduce, but it does not create the variation itself.
Prior to fertilisation, a secondary oocyte will arrest at which stage of meiosis?
prophase I
prophase II
metaphase I
metaphase II
Reveal Answer
prophase I
Primary oocytes arrest in prophase I (specifically the diplotene stage) from birth until puberty, whereas the question refers to the secondary oocyte.
prophase II
Secondary oocytes do not arrest at prophase II; they proceed through this phase and arrest at the subsequent metaphase stage.
metaphase I
Metaphase I occurs during the first meiotic division, which is completed just before ovulation to produce the secondary oocyte.
metaphase II
After ovulation, the secondary oocyte arrests in metaphase II and only completes meiosis if fertilization occurs.
Atlantic salmon (Salmo salar) are fish that are farmed in the waters of Tasmania. A selective breeding program was introduced that focused on increasing the growth of the fish, increasing the resistance of the fish to disease and maintaining the colour and oil content of the fish meat. The selective breeding program resulted in at least a 10% increase in growth of the fish in each generation. Increased resistance to disease has been noted as fewer fish in each generation have required treatment for disease.
In this selective breeding program
offspring will be produced by random mating of parents.
genetic variation within the fish population will increase.
the frequency of alleles for the desired phenotypes will increase over generations.
maintaining the colour and oil content of the fish meat will be advantageous for the fish.
Reveal Answer
offspring will be produced by random mating of parents.
Selective breeding relies on non-random mating, as humans specifically choose which individuals reproduce based on their desired traits.
genetic variation within the fish population will increase.
Selective breeding typically decreases genetic variation because only a small subset of the population with specific traits is chosen to reproduce, eliminating other alleles.
the frequency of alleles for the desired phenotypes will increase over generations.
By consistently selecting individuals with desired traits to reproduce, the alleles responsible for those phenotypes become more common in the population over successive generations.
maintaining the colour and oil content of the fish meat will be advantageous for the fish.
Maintaining meat colour and oil content is advantageous for human consumers and commercial value, not for the biological fitness or survival of the fish.
A key difference between binary fission and mitosis is that
binary fission is a type of nuclear division, but mitosis is not.
homologous chromosomes pair during mitosis, but not in binary fission.
DNA replication occurs during binary fission, but not during mitosis.
binary fission produces two daughter cells, but mitosis does not.
Reveal Answer
binary fission is a type of nuclear division, but mitosis is not.
Incorrect. Mitosis is specifically the division of the nucleus in eukaryotes, while binary fission occurs in prokaryotes which do not have a nucleus.
homologous chromosomes pair during mitosis, but not in binary fission.
Incorrect. The pairing of homologous chromosomes is a key feature of meiosis, not mitosis or binary fission.
DNA replication occurs during binary fission, but not during mitosis.
Correct. In eukaryotes, DNA replication happens before mitosis during the S phase of the cell cycle, whereas in prokaryotes, DNA replication occurs simultaneously with the process of binary fission.
binary fission produces two daughter cells, but mitosis does not.
Incorrect. Both binary fission and mitosis are forms of cell division that result in the production of two genetically identical daughter cells.
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.
During mating, many male redback spiders position themselves above the jaws of the female even though they are more likely to be eaten than males in other positions. These males are, however, able to copulate for longer and fertilise more eggs. On this basis, male positioning above the jaws of the female likely evolved by
natural selection.
sexual selection.
artificial selection.
directional selection.
Reveal Answer
natural selection.
While sexual selection is a specialized form of natural selection, natural selection typically favors traits that improve survival. In this case, the behavior actively decreases the male's survival, making sexual selection the more precise term.
sexual selection.
Sexual selection specifically drives the evolution of traits that maximize mating and reproductive success (fertilizing more eggs), even if those traits come at a significant cost to the organism's survival.
artificial selection.
Artificial selection occurs when humans intentionally breed organisms for specific traits, which does not apply to the natural mating behaviors of wild spiders.
directional selection.
Directional selection describes a shift toward an extreme phenotype over time, but it does not specifically explain the evolutionary trade-off between mating success and survival seen in this behavior.
Which of the following is an advantage of internal fertilisation?
Decreases the risk of gamete dehydration
Increases the number of gametes released
Increases the number of zygotes at one time
Decreases the care provided to gamete and offspring
Reveal Answer
Decreases the risk of gamete dehydration
Internal fertilisation occurs inside the female's body, providing a moist environment that protects the gametes from drying out, which is a crucial adaptation for terrestrial animals.
Increases the number of gametes released
Internal fertilisation typically involves the release of fewer gametes compared to external fertilisation, because the enclosed environment significantly increases the chances of successful sperm-egg fusion.
Increases the number of zygotes at one time
External fertilisation usually produces a much larger number of zygotes at once to compensate for high environmental risks and predation, whereas internal fertilisation generally results in fewer zygotes.
Decreases the care provided to gamete and offspring
Internal fertilisation is generally associated with greater parental investment and protection for both the developing zygote and the resulting offspring, not less.
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 |
Outline a process used by fungi for reproduction.
Reveal Answer
Fungi can reproduce asexually by producing spores which are released and when carried into a favourable environment they germinate and grow into a new fungal organism.
| Descriptor | Marks |
|---|---|
Outlines a process used by fungi for reproduction | 2 |
Provides some relevant information | 1 |
None of the above | 0 |
Outline an adaptation in a pathogen that facilitates transmission between hosts.
Reveal Answer
After colonising a host, fungi can produce spores which can be released to infect a new host.
| Descriptor | Marks |
|---|---|
Outlines how a pathogen adaptation facilitates transmission between hosts | 2 |
Provides some relevant information | 1 |
None of the above | 0 |
Artificial selection has been used for thousands of years to produce crop varieties with desirable characteristics.
Describe how artificial selection can be used to produce a crop variety with desirable characteristics and three advantages and three disadvantages of using artificial selection to produce a new crop variety.
Reveal Answer
The process of artificial selection involves selective breeding of individuals with desired characteristics or traits selected by humans. These individuals pass alleles for the characteristic to their offspring, so the frequency of alleles producing the desired trait increases in the next generation. This process is repeated over many generations until the alleles become common or eventually all individuals show the characteristics.
The advantages are that it is a natural process and only uses alleles already present in the species. There is a low risk of unexpected environmental impacts and does not require much specialist knowledge.
The disadvantages are that the response or change may be limited because it only uses alleles already present in the species. It can take many generations to bring about change. Furthermore, it can decrease genetic diversity, and result in undesirable changes in other characteristics.
Process of artificial selection
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 4 of):
| 4 |
Advantages
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 3 of):
| 3 |
Disadvantages
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 3 of):
| 3 |
Sexual reproduction, through the processes of meiosis and fertilisation, produces genotypic variation.
Explain the two main ways in which the process of meiosis results in variation in genotypes.
Reveal Answer
Crossing-over involves the exchange of alleles between non-sister chromatids in a homologous pair. It occurs during meiosis I or prophase I and results in chromosomes with new combinations of alleles.
Independent assortment occurs during meiosis I, metaphase I, or anaphase I, when homologous chromosomes randomly orientate in the centre of the cell. The maternal and paternal chromosomes in a set move to different poles at random, and different sets of homologous chromosomes move independently of each other. As a result, each pole ends up with a novel combination of maternal and paternal chromosomes.
Crossing-over
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 5 of):
| 5 |
Independent assortment
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 5 of):
| 5 |
Only 35% of the world’s adult human population can digest lactose, which is found in milk. These people continue to produce the enzyme lactase throughout their lives. Most people who can digest lactose have European ancestry. There is evidence that people kept animals for milk in Europe 10 500 years ago.
About 7500 years ago in central Europe, a gene mutation occurred in the lactase gene, where cytosine was replaced by thymine. The allele produced by this mutation allows individuals to produce lactase and to digest lactose throughout their lives.
Researchers have estimated that populations in Europe with this mutation produced more offspring than populations who did not have this mutation.
Name the type of mutation that occurred 7500 years ago in central Europe.
Reveal Answer
For example: Point mutation.
| Descriptor | Marks |
|---|---|
1 mark for any one of:
| 1 |
The increase in frequency of the allele for lactase persistence happened relatively quickly in some populations.
Explain why the frequency of this allele increased relatively quickly.
Reveal Answer
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 3 of):
| 3 |
In some present-day populations there are no individuals with the mutation.
Give two reasons for the absence of the mutation in these populations.
Reveal Answer
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Cows are the main source of milk in Europe. Modern dairy cow breeds can produce 25 L of milk each day – much more than their wild ancestors.
Describe how an increase in production of cow’s milk could be achieved by farmers over many generations of cows.
Reveal Answer
The farmers would select the cows that produce the most milk. These cows would be bred.
| Descriptor | Marks |
|---|---|
States farmers would select the cows that produce the most milk. | 1 |
States these cows would be bred. | 1 |
The malleefowl (Leipoa ocellata) is a ground-dwelling bird that is found in scrubland in southern Australia. It is vulnerable to extinction.
The following terms are relevant to developing conservation plans for the malleefowl. Define each term.
Gene pool
Reveal Answer
It is all of the genetic information in a species.
| Descriptor | Marks |
|---|---|
Defines the term as all of the genes/alleles/genetic diversity/genetic information in a population/species | 1 |
Population dynamics
Reveal Answer
It is the study of changes in population size.
| Descriptor | Marks |
|---|---|
Defines the term as the study of changes in population size OR of how and why populations change size OR of the size and age composition of populations | 1 |
Biogeography
Reveal Answer
It is the study of the geographical distribution of organisms.
| Descriptor | Marks |
|---|---|
Defines the term as the study of the geographical distribution of organisms/species/communities | 1 |
Reproductive behaviour
Reveal Answer
It is the behaviour associated with mating.
| Descriptor | Marks |
|---|---|
Defines the term as behaviour associated with mating OR rearing young | 1 |
To investigate genetic diversity, biologists produced DNA profiles for malleefowl. List the main steps involved in producing a DNA profile.
Reveal Answer
First, extract DNA from the malleefowl. Then, use PCR to amplify the DNA. Next, use electrophoresis to separate the DNA fragments. Finally, record the DNA sequence.
| Descriptor | Marks |
|---|---|
States to extract/isolate/obtain DNA (from the malleefowl) | 1 |
States to (PCR) amplify DNA/make large amounts of DNA/clone DNA | 1 |
States to use electrophoresis to separate DNA fragments/pieces OR to visualise DNA | 1 |
States to record the DNA sequence OR number of short tandem repeats/STRs OR restriction enzyme fragments | 1 |
Biologists are breeding malleefowl in captivity to assist in the recovery of wild populations. Describe two ways in which captive breeding can assist in the recovery of wild populations.
Reveal Answer
Release genetically diverse individuals to maintain the genetic diversity of wild populations.
Additionally, release large numbers of individuals to boost the population size.
| Descriptor | Marks |
|---|---|
States to release genetically diverse individuals | 1 |
Explains that this is to boost/maintain genetic diversity (of wild populations) | 1 |
States to release additional/large numbers of individuals | 1 |
Explains that this is to boost population size | 1 |
Explain how a consideration of population dynamics can assist conservation planning to maintain viable gene pools in a vulnerable species, such as the malleefowl.
Reveal Answer
It can identify trends in population size. The smallest population sizes pose the most risk to the gene pool Therefore, conservation planning should be based around the smallest population size. Furthermore, it can identify and potentially correct factors that cause numbers to drop.
| Descriptor | Marks |
|---|---|
States that it can identify trends in population size OR when populations will grow/decline | 1 |
Explains that the smallest population sizes pose the most risk to the gene pool OR the population will lose genetic diversity when small | 1 |
Concludes that conservation planning should be based around the smallest population size OR should allow for times when population numbers will drop OR should consider small sizes in the past | 1 |
States that it can identify and potentially correct factors that cause numbers to drop | 1 |
Habitat destruction has reduced the opportunity for gene flow between malleefowl populations. Explain how gene flow affects the gene pool of a population.
Reveal Answer
Gene flow is the exchange of alleles between populations. Gene flow, can bring new alleles into the gene pool because they come from populations with different alleles. Furthermore, gene flow, can change allele frequencies in the gene pool.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 4 of):
| 4 |