NESA Biology Questioning and Predicting
4 sample questions with marking guides and sample answers · Avg. score: 57.6%
A four-month investigation was undertaken in the classrooms of a large number of Year 2 and Year 3 students from four primary schools. For the first two months, half of the classes from each school used an antimicrobial gel hand sanitiser, while the other half used soap and water for regular hand hygiene. The students then switched hand-cleaning methods for the final two months. No significant differences in illness were observed between the groups.
The purpose of this investigation was most likely to
reduce water use in schools.
encourage students to wash their hands more often.
reduce the number of students who are away from school due to illness.
decide if purchasing antimicrobial gel hand sanitiser for students was worthwhile.
Reveal Answer
reduce water use in schools.
The investigation measured illness rates, not water consumption, so reducing water use was not the primary purpose of the study.
encourage students to wash their hands more often.
The study compared the effectiveness of two different hand-cleaning methods rather than trying to increase the overall frequency of handwashing.
reduce the number of students who are away from school due to illness.
Although reducing illness is a broad goal, the study specifically compared two methods to see if one was more effective, rather than just implementing a general illness reduction program.
decide if purchasing antimicrobial gel hand sanitiser for students was worthwhile.
By comparing the effectiveness of the sanitiser against standard soap and water in preventing illness, the schools could determine if the sanitiser offered enough benefit to justify its purchase.
Most vinegar flies have wild type (reddish-brown) eyes. However, some mutants have white eyes and cannot see. Biologists conducted a laboratory experiment to compare the fitness of flies with wild type and white eyes.
Which of the following is the best hypothesis for the experiment?
Is there a difference in the fitness of flies with wild type and white eyes?
There is a difference in the fitness of flies with wild type and white eyes.
If flies cannot see, then they will have reduced fitness.
Do flies that cannot see have reduced fitness?
Reveal Answer
Is there a difference in the fitness of flies with wild type and white eyes?
A hypothesis must be a testable statement, not a question. This option represents a research question rather than a hypothesis.
There is a difference in the fitness of flies with wild type and white eyes.
This is the best hypothesis because it is a clear, testable statement that proposes a relationship between the variables being investigated (eye type and fitness).
If flies cannot see, then they will have reduced fitness.
While related to the experiment, this is formatted as a prediction (an "if-then" statement) rather than a formal hypothesis comparing the two specific phenotypes.
Do flies that cannot see have reduced fitness?
Like option A, this is phrased as a question. A scientific hypothesis must be a declarative statement that can be tested.
Thalassemia is a genetically inherited disorder that affects the haemoglobin of blood. Two types of thalassemia are alpha (α) and beta (β). One of the treatments of both types of thalassemia involves drugs that are administered to help remove excess iron from the blood. A research team wanted to investigate the effectiveness of the different modes of delivery of these drugs.
The team set up an investigation to compare the drugs in injectable form with the orally ingested form. The team conducted their investigation on a sample of 53 beta (β) thalassemia sufferers. The participants were divided into four groups. The participants in each group had daily treatments lasting one month. The groups were:
Group A – 14 participants who received the injectable drug
Group B – 13 participants who received an inactive injectable drug
Group C – 13 participants who received the orally ingested drug
Group D – 13 participants who received an inactive oral drug.
Propose an hypothesis for the study described above.
Reveal Answer
Example: Injectable drugs will be more effective in treating thalassemia symptoms than orally ingested drugs.
| Descriptor | Marks |
|---|---|
Provides a testable, predictive statement (e.g., injectable drugs will be more effective in treating thalassemia symptoms than orally ingested drugs) | 1 |
Why were both groups B and D required for this study?
Reveal Answer
They act as control groups of the study to compare results with. They both administer the placebo treatment to minimise any psychological effects, and the study needs both as there are two different modes of delivery that need to be equally controlled.
| Descriptor | Marks |
|---|---|
Identifies them as control groups of the study to compare results with | 1 |
States that they both administer the placebo treatment to minimise any psychological effects | 1 |
Explains that both are needed as there are two different modes of delivery that need to be equally controlled | 1 |
Identify a variable that was controlled in the study.
Reveal Answer
That all participants have the same type of thalassemia.
| Descriptor | Marks |
|---|---|
Identifies a controlled variable, such as the treatment schedule (daily treatments for a month) or that all participants have the same type of thalassemia | 1 |
Describe the data the researchers would need to collect and when they should collect the data.
Reveal Answer
They should test for the levels of iron found in the blood. Testing should be done before treatment and at the end of the one-month treatment.
| Descriptor | Marks |
|---|---|
States to test for the levels of iron found in the blood | 1 |
States that testing should be done before treatment | 1 |
States that testing should be done at the end of the one-month treatment | 1 |
Outline the cause of alpha (α) and beta (β) thalassemia and identify what makes each type of thalassemia different.
Reveal Answer
It is caused by a mutation of the gene responsible for haemoglobin production.
Alpha () thalassemia affects genes on chromosome 16.
Beta () thalassemia affects genes on chromosome 11.
| Descriptor | Marks |
|---|---|
Identifies a mutation of the gene responsible for red blood cells or haemoglobin production | 1 |
Explains that alpha () thalassemia affects genes on chromosome 16 or reduces the formation of alpha polypeptide chains or the alpha globin of red blood cells | 1 |
Explains that beta () thalassemia affects genes on chromosome 11 or reduces the formation of beta polypeptide chains or the beta globin of red blood cells | 1 |
Alpha (α) and beta (β) thalassemia display the same inheritance pattern but can have differing effects on the gene pool of a population. Justify this statement.
Reveal Answer
Both are recessive traits, and heterozygotes are mildly affected with the disease.
The homozygous condition in alpha thalassemia is fatal, whereas the homozygous condition in beta thalassemia is severe but not fatal. Therefore, there are no homozygote alpha sufferers present in a population, but there will be beta sufferers.
| Descriptor | Marks |
|---|---|
States that both are recessive traits | 1 |
Explains that heterozygotes are mildly affected with the disease or that heterozygous carrier parents pass the traits on to their children | 1 |
States that the homozygous condition in alpha thalassemia is fatal | 1 |
States that the homozygous condition in beta thalassemia is severe but not fatal | 1 |
Concludes that there are no homozygote alpha sufferers present in a population but there will be beta sufferers | 1 |
In 2009, the University of California discovered a mutated gene that has been shown to produce naturally short sleepers. The gene was found in a family who all normally went to bed around 11 pm and woke up naturally around 5 am. The mutated gene, known as DEC2, is believed to affect the circadian rhythm and results in people who don't need as much sleep as the average person.
If researchers wanted to further investigate the link between the DEC2 gene and sleep, they would need to set up an experimental study.
DEC2 is a gene mutation. How do gene and chromosomal mutations differ?
Reveal Answer
Gene mutations only affect one gene (loci), whereas chromosomal mutations affect more than one gene.
| Descriptor | Marks |
|---|---|
States that gene mutations only affect one gene (loci) or a small section of DNA | 1 |
States that chromosomal mutations affect more than one gene, part of a chromosome, or a whole chromosome | 1 |
In the study, the mutation was found in several family members. What does this tell you about where the original mutation occurred? Justify your response.
Reveal Answer
It occurred in the cells that produce the gamete, and only mutations produced in these cells can be inherited.
| Descriptor | Marks |
|---|---|
Identifies that it occurred in the cells that produce the gamete (germline) or a germline cell | 1 |
Explains that only mutations produced in these cells can be inherited or passed on | 1 |
Mutations can be caused in several ways. For each of the three ways stated below, describe how they may produce new mutations.
-
Mutagens:
-
DNA replication:
-
Cell division:
Reveal Answer
Mutagens are substances that are known to increase the rate of changes to DNA, such as ionising radiation, mustard gas, or formaldehyde.
During DNA replication, errors during the process can alter the DNA code, which can be deleting, duplicating, insertions, or frameshifts of DNA.
During cell division, errors during the process can alter the genes or chromosomes in the daughter cells formed, such as be non-disjunction, translocation, or inversions of DNA.
Mutagens
| Descriptor | Marks |
|---|---|
Describes mutagens as substances that are known to increase the (rate of) changes to DNA | 1 |
Provides examples including ionising radiation, mustard gas, some antibiotics, or formaldehyde | 1 |
DNA replication
| Descriptor | Marks |
|---|---|
Describes errors during the process that alter DNA code | 1 |
Identifies that these can be deleting, duplicating, insertions, or frameshifts of DNA | 1 |
Cell division
| Descriptor | Marks |
|---|---|
Describes errors during the process that alter the genes or chromosomes in daughter cells formed | 1 |
Identifies that these can be non-disjunction, translocation, or inversions of DNA | 1 |
Propose a possible hypothesis for the study.
Reveal Answer
For example: Individuals with the DEC2 gene will sleep less hours a night.
| Descriptor | Marks |
|---|---|
Provides a statement that contrasts the presence/absence of the DEC2 gene and amount of sleep required (e.g. individuals with the DEC2 gene will sleep less hours a night) | 1 |
In the study, what would the control group consist of, and what purpose would it have?
Reveal Answer
Individuals without the DEC2 gene act as a comparison to the experimental group.
| Descriptor | Marks |
|---|---|
Identifies individuals without the DEC2 gene | 1 |
States that they act as a comparison to the experimental group | 1 |
A mutation, such as the DEC2 gene, could be favourable to the human population. Explain how a favourable gene like this could lead to changes in allele frequencies of a gene pool.
Reveal Answer
Mutations introduce new alleles into the population. These alleles may produce traits favourable to survival. Favourable alleles are then passed to offspring, and favourable traits will increase in number within the gene pool.
| Descriptor | Marks |
|---|---|
States that mutations introduce new alleles into the population or create variation | 1 |
States that alleles may produce traits favourable to survival | 1 |
States that favourable alleles are passed to offspring | 1 |
Explains that favourable traits will increase in number within the gene pool or natural selection will produce changes to the gene pool | 1 |