NESA Biology Epidemiology
10 sample questions with marking guides and sample answers · Avg. score: 73.5%
Over 12 months, the prevalence of a non-infectious disease will increase in a population if
the total population increases.
disease recovery time decreases.
the incidence rate of the disease decreases.
the survival time of individuals with the disease increases.
Reveal Answer
the total population increases.
Prevalence is the proportion of the population with the disease. If the total population increases without a proportional increase in cases, the prevalence actually decreases.
disease recovery time decreases.
Decreasing recovery time means individuals have the disease for a shorter duration. Because , a shorter duration decreases prevalence.
the incidence rate of the disease decreases.
Incidence is the rate of new cases. A decrease in incidence means fewer new cases are added, which would decrease rather than increase prevalence.
the survival time of individuals with the disease increases.
The relationship between prevalence and incidence is . If survival time increases, the duration of the disease increases, causing individuals to remain in the diseased population longer and increasing overall prevalence.
Bevacizumab is a humanised monoclonal antibody that is used to treat several different cancers. Humanising involves removing part of the constant region of a mouse monoclonal antibody and replacing it with the constant region from a human antibody. Therefore the humanised antibody has both human-derived and mouse-derived components.
An advantage of humanising monoclonal antibodies such as bevacizumab would be to
decrease the binding strength between bevacizumab and the cancer cell antigens.
reduce the chances of an immune response against bevacizumab.
allow greater destruction of cancerous and non-cancerous cells.
deliver toxic substances less effectively to the cancer cells.
Reveal Answer
decrease the binding strength between bevacizumab and the cancer cell antigens.
The goal of humanising an antibody is not to decrease its binding strength, as strong binding to the target antigen is necessary for its therapeutic effect.
reduce the chances of an immune response against bevacizumab.
By replacing mouse components with human components, the antibody appears less 'foreign' to the patient's immune system, significantly reducing the risk of an adverse immune response against the treatment.
allow greater destruction of cancerous and non-cancerous cells.
Monoclonal antibodies are designed to specifically target cancer cells, so increasing the destruction of non-cancerous cells would be a harmful side effect, not an advantage.
deliver toxic substances less effectively to the cancer cells.
Delivering toxic substances less effectively would reduce the efficacy of the treatment, which is a disadvantage rather than an advantage.
Parkinson's disease can potentially be treated using cell replacement therapy. The purpose of using this therapy would be to replace the cells that
would normally function within the cerebral cortex.
would normally function within the cerebellum.
produce dopamine in the brain.
produce noradrenaline in the brain.
Reveal Answer
would normally function within the cerebral cortex.
Parkinson's disease primarily involves the degeneration of neurons in the substantia nigra, a part of the basal ganglia, rather than the cerebral cortex.
would normally function within the cerebellum.
While the cerebellum is involved in motor control, it is not the primary region affected by cell loss in Parkinson's disease.
produce dopamine in the brain.
Parkinson's disease is characterized by the progressive loss of dopamine-producing neurons in the substantia nigra, so cell replacement therapy aims to restore these specific cells.
produce noradrenaline in the brain.
Although noradrenaline levels can be affected in Parkinson's, the hallmark of the disease and the primary target for cell replacement therapy is the loss of dopamine-producing cells.
A promising experimental therapy being used to treat Parkinson's disease involves the use of
stem cells to replace damaged or dysfunctional dopamine-producing neurons.
gene therapy to fix mutated DNA sequences in brain cells.
protein blockers to prevent the building up of amyloid plaques in the brain.
invasive brain stimulation therapy to activate dysfunctional neurons.
Reveal Answer
stem cells to replace damaged or dysfunctional dopamine-producing neurons.
Parkinson's disease is primarily caused by the progressive loss of dopamine-producing neurons. Stem cell therapy is a major experimental approach aimed at differentiating stem cells into new neurons to replace those that have died.
gene therapy to fix mutated DNA sequences in brain cells.
While gene therapy is being researched, most cases of Parkinson's disease are sporadic rather than caused by a single genetic mutation, making direct DNA repair less universally applicable than cell replacement.
protein blockers to prevent the building up of amyloid plaques in the brain.
The buildup of amyloid plaques is a hallmark of Alzheimer's disease, not Parkinson's disease. Parkinson's is instead associated with the accumulation of alpha-synuclein proteins, known as Lewy bodies.
invasive brain stimulation therapy to activate dysfunctional neurons.
Deep brain stimulation (DBS) is an invasive therapy used to treat Parkinson's symptoms, but it is an established, FDA-approved treatment rather than an experimental one.
Cell replacement therapy for the treatment of Parkinson's disease involves the
injection of adult stem cells to replace neurons in the brain that have been damaged by the build-up of plaque.
differentiating of stem cells into dopamine-signalling neurons and transplanting them into a patient's brain to replace dying neurons.
patient's own neurons being extracted with the DNA inside the cells then altered and the cells reinserted into the patient's body.
extraction of non-functioning neurons and replacing them with new cells that have the correct gene and can function normally.
Reveal Answer
injection of adult stem cells to replace neurons in the brain that have been damaged by the build-up of plaque.
This option is incorrect because the build-up of plaque is a characteristic of Alzheimer's disease, not Parkinson's disease.
differentiating of stem cells into dopamine-signalling neurons and transplanting them into a patient's brain to replace dying neurons.
This is correct because Parkinson's disease is caused by the loss of dopamine-producing neurons, and cell replacement therapy aims to replace these specific cells by transplanting differentiated stem cells.
patient's own neurons being extracted with the DNA inside the cells then altered and the cells reinserted into the patient's body.
This option describes ex vivo gene therapy rather than cell replacement therapy. Additionally, extracting and reinserting a patient's own neurons is not a feasible treatment for Parkinson's.
extraction of non-functioning neurons and replacing them with new cells that have the correct gene and can function normally.
This is incorrect because cell replacement therapy does not involve the physical extraction of non-functioning neurons; it only involves transplanting new cells to compensate for the dying ones.
Mosunetuzumab is a bispecific monoclonal antibody. Bispecific antibodies are designed to simultaneously bind to two different targets, such as a cancer cell antigen and a cytotoxic T cell. The T cell then destroys the cancer cell.
Mosunetuzumab’s bispecificity would arise from the fact that it
lacks a constant region.
contains only heavy chains.
contains both a light and a heavy chain.
has two different-shaped variable regions.
Reveal Answer
lacks a constant region.
The constant region of an antibody determines its effector function (how it interacts with immune cells), not its antigen-binding specificity.
contains only heavy chains.
While some animals produce heavy-chain-only antibodies, this structural feature does not inherently allow an antibody to bind to two different targets.
contains both a light and a heavy chain.
Standard monospecific antibodies also contain both light and heavy chains, so this feature alone does not explain the ability to bind two different targets.
has two different-shaped variable regions.
The variable regions of an antibody are responsible for binding to specific antigens. Having two different-shaped variable regions allows the bispecific antibody to bind to two distinct targets simultaneously.
A new treatment for some cancers includes the use of conjugated monoclonal antibodies, which have an anti-cancer drug attached.
The main advantage of using conjugated monoclonal antibodies in this new cancer treatment is that they
decrease the amount of the anti-cancer drug delivered to cancerous cells.
reduce the effects of the anti-cancer drug on non-cancerous cells.
cause an increase in the number of memory T cells.
stimulate B cells to produce antibodies.
Reveal Answer
decrease the amount of the anti-cancer drug delivered to cancerous cells.
Conjugated monoclonal antibodies are designed to specifically target cancer cells, which actually concentrates and increases the delivery of the drug to those cells, rather than decreasing it.
reduce the effects of the anti-cancer drug on non-cancerous cells.
Because monoclonal antibodies specifically bind to antigens found on cancer cells, the attached drug is delivered directly to the tumor. This targeted approach spares healthy, non-cancerous cells from the drug's toxic side effects.
cause an increase in the number of memory T cells.
Monoclonal antibodies provide targeted drug delivery and passive immunity; they do not act as vaccines to stimulate the immune system to produce memory T cells.
stimulate B cells to produce antibodies.
Administering monoclonal antibodies is a form of passive immunity. It delivers pre-made antibodies directly to the patient rather than stimulating the patient's own B cells to produce them.
A vaccine for cancer
Scientists are investigating whether it is possible to produce a vaccine that will work against cancer cells.
Currently there are vaccines available against certain viruses that are known to cause cancer. For example, the human papillomavirus vaccine is highly effective in preventing cervical cancer. The vaccine contains virus-like particles that have antigens that are found on the surface of the human papillomavirus. These antigens stimulate an immune response when injected into the individual but do not cause disease. The vaccine is very effective as the immune response produces high levels of antibodies.
This example is considered a conventional vaccine. Conventional vaccines contain either a dead or inactivated version of a pathogen, or a protein from that pathogen. Conventional vaccines can take many months to produce.
As most cancers are not caused by viruses, scientists investigated whether a non-conventional vaccine could be developed. A vaccine containing mRNA was produced. mRNA codes for the production of a protein that must be produced by the cells of the individual injected with the vaccine. This protein manufactured by the cells acts as an antigen and, when released from the cells, results in an immune response within the individual.
The scientists determined the genetic code of an antigen found on the surface of a particular cancer cell. They assembled a molecule of mRNA that would code for this antigen. Many copies of this mRNA molecule were then incorporated into a vaccine. In December 2019, a clinical trial to test for a new type of vaccine took place. Individuals injected with the mRNA vaccine produced an immune response that resulted in antibodies that acted against the antigen found on the surface of the cancer cells.
Scientists realised that they could potentially quickly produce vaccines for many different cancers by changing the nucleotide sequence of the mRNA molecule. However, designing vaccines for cancers is not that simple. Cancer cells can easily evade immune cells and continue to reproduce. Mutations can cause changes to the target antigens on the surface of cancer cells. A vaccine designed for one person may not work for another person as their cancers have different mutations.
According to the article, what are the contents of conventional vaccines and how do they lead to an improved immune response when a person encounters a pathogen?
Reveal Answer
The conventional vaccines contained the dead or inactivated version of the pathogen. This resulted in the production of memory cells or faster and larger antibody production.
| Descriptor | Marks |
|---|---|
Identifies that conventional vaccines contain a dead or inactivated version of the pathogen (or a protein from the pathogen). | 1 |
Explains that this results in the production of memory cells OR faster and larger antibody production upon encountering the pathogen. | 1 |
Explain how mRNA vaccines are different from conventional vaccines.
Reveal Answer
mRNA vaccines contain mRNA, allowing the individual to create the antigen.
| Descriptor | Marks |
|---|---|
States that mRNA vaccines contain mRNA. | 1 |
Explains that this allows the individual's own cells to manufacture the antigen. | 1 |
Using the information in the article above, identify the advantages of developing mRNA vaccines for the treatment of cancer. Outline an ethical concept that should be taken into account when developing mRNA vaccines.
Reveal Answer
mRNA vaccines can be quickly produced in order to treat different cancers, resulting in the production of antibodies specific to cancer and not to other cells.
Advantages
| Descriptor | Marks |
|---|---|
Identifies that mRNA vaccines can be quickly produced. | 1 |
Identifies that they can be adapted to treat different cancers OR result in the production of antibodies specific to cancer cells. | 1 |
Ethical Concept
| Descriptor | Marks |
|---|---|
Identifies a relevant ethical concept (e.g., justice, integrity, non-maleficence, beneficence, or respect). | 1 |
Outlines the chosen ethical concept in the context of developing mRNA vaccines (e.g., justice: ensuring the vaccine is available to everyone; integrity: honest communication of trial results; non-maleficence: ensuring the vaccine does not cause harm; beneficence: ensuring benefits outweigh potential harm; respect: gaining informed consent from trial participants). | 1 |
Christian, a 40-year-old man, was recently diagnosed with Type 2 diabetes. Christian was classified as obese according to his body mass index and his fasting blood glucose level was very high being measured at 10.3 mmol L. In addition to changes to his diet and increased exercise, Christian's doctor prescribed a drug to promote weight loss and lower Christian's blood glucose levels. This drug mimics a natural water-soluble hormone in the human body, enhancing the action of insulin and reducing glucagon levels.
Explain how the following glands maintain blood glucose levels during fasting: ...
Outline how water-soluble hormones influence their target cells.
Reveal Answer
They attach to receptor proteins in the membrane of the target cell, forming a hormone-receptor complex. This activates a secondary messenger inside the cytoplasm or cell, activating particular enzymes, and having a short-lived response.
| Descriptor | Marks |
|---|---|
States that they attach to receptor proteins in the membrane of the target cell | 1 |
Describes the formation of a hormone-receptor complex | 1 |
Explains that this activates a secondary messenger inside the cytoplasm/cell | 1 |
States that this activates particular enzymes/increases enzyme concentration | 1 |
Describes the response as having a fast onset/short-lived response | 1 |
... pancreas
Reveal Answer
Low blood glucose levels are detected by chemoreceptors, and the alpha cells are stimulated. Glucagon is secreted, stimulating glycogenolysis, which is the breakdown of glycogen to glucose, and gluconeogenesis, which is the production of glucose from amino acids and fats. Both of these processes primarily occur in the liver. It also stimulates lipolysis, the breakdown of fats, which occurs in most body cells or adipose tissue.
| Descriptor | Marks |
|---|---|
States that low blood glucose levels are detected | 1 |
Identifies that detection is by chemoreceptors | 1 |
States that the Islets of Langerhans/alpha cells are stimulated | 1 |
States that glucagon is secreted | 1 |
Describes the stimulation of glycogenolysis/breakdown of glycogen to glucose | 1 |
Describes the stimulation of gluconeogenesis/production of glucose from amino acids and fats | 1 |
States that both processes primarily occur in the liver | 1 |
Describes the stimulation of lipolysis/breakdown of fats | 1 |
States that lipolysis occurs in most body cells/adipose tissue | 1 |
... adrenal glands
Reveal Answer
The adrenal medulla secretes adrenaline/noradrenaline, and the adrenal cortex secretes cortisol. This further enhances the rate of glucose production, increasing blood glucose by gluconeogenesis/glycogenolysis.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 3 of): States that the adrenal medulla secretes adrenaline/noradrenaline; States that the adrenal cortex secretes cortisol; Explains that this further enhances the rate of glucose production/increases blood glucose; Identifies that this occurs by gluconeogenesis/glycogenolysis | 3 |
Explain why a patient with Type 1 diabetes would not be prescribed the drug from the above scenario to manage their blood glucose levels.
Reveal Answer
Type 1 diabetes is the inability to produce insulin. The drug works to enhance insulin activity, so if there is no insulin being produced, the drug will have no effect.
| Descriptor | Marks |
|---|---|
Defines Type 1 diabetes as the inability to produce insulin | 1 |
States that the drug works to enhance insulin activity | 1 |
Concludes that if there is no insulin being produced, the drug will have no effect | 1 |
Changes to the amount of thyroxine being released from the thyroid gland can have major impacts on the functioning of the body.
Name each of the disorders that may lead to an over-secretion or under-secretion of thyroxine; describe how the over-secretion or under-secretion impacts on the body; and explain how each disorder can be treated.
Reveal Answer
Hypothyroidism is a disorder where low levels of thyroxine lead to a decrease in metabolic rate. This causes symptoms such as decreased heart rate and decreased blood pressure. Treatments include increasing iodine in the diet, taking synthetic hormone tablets, or surgery.
Conversely, hyperthyroidism is a disorder where high levels of thyroxine lead to overstimulation of body cells. This causes symptoms such as increased heart rate and high blood pressure. Treatments include taking drugs to block the thyroid's use of iodine, surgery to remove all or part of the gland, or radioactive iodine.
Disorder Identification
| Descriptor | Marks |
|---|---|
Identifies Hypothyroidism/Hashimoto's disease | 1 |
Identifies Hyperthyroidism/Graves' disease | 1 |
Impacts
| Descriptor | Marks |
|---|---|
Describes that low levels of thyroxine lead to a decrease in metabolic rate causing symptoms | 1 |
Describes that high levels of thyroxine lead to overstimulation of body cells causing symptoms | 1 |
Symptoms
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of) for Hypothyroidism:
| 2 |
1 mark for each correct point (any 2 of) for Hyperthyroidism:
| 2 |
Treatments
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of) for Hypothyroidism:
| 2 |
1 mark for each correct point (any 2 of) for Hyperthyroidism:
| 2 |
Explain the role of the liver in the maintenance of blood glucose levels.
Reveal Answer
Glucose is removed from blood to provide energy for liver functioning.
Glucose also converted to glycogen by the process of glycogenesis controlled by insulin, and glycogen is stored in the liver.
When blood sugar levels fall glycogen is converted back to glucose by the process of glycogenolysis, which is controlled by glucagon
| Descriptor | Marks |
|---|---|
glucose removed from blood to provide energy for liver functioning | 1 |
glucose also converted to glycogen | 1 |
by the process of glycogenesis | 1 |
controlled by insulin | 1 |
glycogen is stored in the liver | 1 |
when blood sugar levels fall glycogen is converted back to glucose | 1 |
by the process of glycogenolysis | 1 |
controlled by glucagon | 1 |