NESA Biology Responses to Pathogens
12 sample questions with marking guides and sample answers · Avg. score: 69.2%
Phytophthora is a pathogen that infects
Australian native plants only.
Australian native animals only.
a broad range of plants.
a broad range of animals.
Reveal Answer
Australian native plants only.
While Phytophthora is a major threat to many Australian native plants, it is not restricted to them and infects plants worldwide.
Australian native animals only.
Phytophthora is a plant pathogen (a type of water mold) and does not infect animals.
a broad range of plants.
Phytophthora is a genus of destructive water molds that are known to infect a wide variety of plant species globally, causing diseases like root rot and potato blight.
a broad range of animals.
Phytophthora specifically targets and infects plants, not animals.
A blood sample from an area of the body exhibiting inflammation would be
high in complement proteins, high in histamine, low in heparin and low in tissue
fluid.
low in complement proteins, low in histamine, low in heparin and high in tissue
fluid.
low in complement proteins, high in histamine, high in heparin and low in tissue
fluid.
high in complement proteins, high in histamine, high in heparin and high in tissue
fluid.
Reveal Answer
high in complement proteins, high in histamine, low in heparin and low in tissue
fluid.
While complement proteins and histamine are elevated during inflammation, heparin and tissue fluid levels would also be high, not low.
low in complement proteins, low in histamine, low in heparin and high in tissue
fluid.
Inflammation triggers the release of complement proteins, histamine, and heparin to fight infection and increase blood flow, so these would all be high, not low.
low in complement proteins, high in histamine, high in heparin and low in tissue
fluid.
Complement proteins are actively recruited during inflammation, and tissue fluid increases due to vascular permeability (causing swelling), so both would be high.
high in complement proteins, high in histamine, high in heparin and high in tissue
fluid.
During inflammation, mast cells release histamine (causing vasodilation) and heparin (preventing clotting), complement proteins are activated to destroy pathogens, and increased capillary permeability leads to high tissue fluid (edema).
Which of the following identifies plant responses to pathogens?
Increased phagocytosis and programmed cell death
Increased number of stomata and programmed cell death
Production of antihistamines and increased thickness of cell walls
Production of antimicrobial substances and increased thickness of cell walls
Reveal Answer
Increased phagocytosis and programmed cell death
Plants do not perform phagocytosis because their rigid cell walls prevent the engulfment of particles, although they do utilize programmed cell death (the hypersensitive response).
Increased number of stomata and programmed cell death
Increasing the number of stomata would actually provide more natural openings for pathogens to enter the plant, making it more vulnerable rather than protecting it.
Production of antihistamines and increased thickness of cell walls
Histamines and antihistamines are components of the animal immune system's inflammatory response, not plant defense mechanisms.
Production of antimicrobial substances and increased thickness of cell walls
Plants defend against pathogens chemically by producing antimicrobial compounds (like phytoalexins) and physically by thickening their cell walls with callose and lignin to block pathogen spread.
Fever plays an important role in humans' defence against disease. This role is best described as
specific immunity, which destroys invading pathogens directly.
non-specific immunity, which helps to speed up the immune response.
specific immunity, which activates the killer T cells and helper T cells.
non-specific immunity, which helps to neutralise pathogens at the entry site.
Reveal Answer
specific immunity, which destroys invading pathogens directly.
Fever is a component of the innate, non-specific immune system, not specific immunity, and it does not destroy pathogens directly.
non-specific immunity, which helps to speed up the immune response.
Fever is a systemic, non-specific immune response that raises body temperature to accelerate metabolic processes, thereby speeding up the overall immune response and tissue repair.
specific immunity, which activates the killer T cells and helper T cells.
While fever can enhance the activity of immune cells, it is classified as a non-specific immune response, not specific immunity.
non-specific immunity, which helps to neutralise pathogens at the entry site.
Fever is a systemic response that affects the whole body, rather than acting locally to neutralize pathogens at their specific site of entry.
During their lifetime, plants are exposed to both pathogenic and beneficial microorganisms. Some plants provide shelter within their bodies for beneficial microorganisms. These beneficial microorganisms help plants that have not been genetically modified to resist pathogenic microorganisms.
The beneficial microorganisms may be providing protection by
synthesising toxins that kill pathogenic microorganisms.
providing a permeable physical barrier to pathogenic microorganisms.
stimulating the production of antibodies against pathogenic microorganisms.
mobilising the cells of the third line of defence against pathogenic microorganisms.
Reveal Answer
synthesising toxins that kill pathogenic microorganisms.
Beneficial microorganisms can produce antimicrobial compounds or toxins that directly inhibit or kill pathogenic microorganisms, thereby protecting the plant.
providing a permeable physical barrier to pathogenic microorganisms.
A permeable barrier would allow substances, including pathogens, to pass through, which would not provide effective physical protection.
stimulating the production of antibodies against pathogenic microorganisms.
Plants do not possess an adaptive immune system and therefore cannot produce antibodies.
mobilising the cells of the third line of defence against pathogenic microorganisms.
The third line of defence refers to the adaptive immune system (involving B and T cells), which is present in vertebrates but absent in plants.
Australian native plants can be infected by fungal and viral pathogens.
Which of the following is an active plant response to infection by pathogens?
Phagocytosis
Programmed cell death
Formation of powdery spots
Development of small stomata
Reveal Answer
Phagocytosis
Phagocytosis is an immune response found in animals, not plants. Plant cells have rigid cell walls that prevent them from engulfing pathogens.
Programmed cell death
Programmed cell death, also known as the hypersensitive response, is an active defense mechanism where plants intentionally kill their own cells at the infection site to deprive the pathogen of nutrients and prevent its spread.
Formation of powdery spots
The formation of powdery spots is a symptom of a fungal infection (such as powdery mildew), rather than an active defense response initiated by the plant.
Development of small stomata
The development of small stomata is a structural adaptation, often related to environmental conditions like drought, rather than an active, induced immune response to a pathogen infection.
All animals produce nitrogenous waste, which must be excreted.
Distinguish between how bony fish and land vertebrates excrete nitrogenous waste.
Reveal Answer
Bony fish mainly excrete ammonia, often via their gills. Ammonia is a by-product of metabolism and requires little to no energy to produce. Although it is toxic, fish can continuously excrete ammonia and do not need to store it because they live surrounded by water in an aquatic environment. However, some marine fish excrete urea due to the need to conserve freshwater.
In contrast, land vertebrates excrete either urea or uric acid, depending on the vertebrate, typically via their kidneys. In these animals, ammonia is converted to urea or uric acid, and this conversion takes energy. Urea and uric acid are less toxic than ammonia, and so can be stored for longer. Furthermore, urea and uric acid need less water to expel, which reduces water needs and is more suitable for land where water is limited. The excretion of uric acid requires less water than urea.
Bony fish
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 5 of):
| 5 |
Land vertebrates
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 5 of):
| 5 |
Chytridiomycosis is a major disease of amphibians worldwide, threatening many species with extinction.
Discuss the impact that chytridiomycosis has on the host amphibian.
Reveal Answer
The disease disrupts skin function because the pathogen infects and damages the outer layer of skin. Breathing is disrupted because amphibians exchange gas, such as CO2 and O2, through their skin.
Osmoregulation is disrupted because ions are transported across the skin. This disrupted ion balance can cause heart failure. The disease also causes neurological effects such as lethargy. These neurological problems can reduce foraging efficiency and make them susceptible to predators, and the disease is often fatal.
Amphibians are particularly susceptible to skin disease because of the importance of their skin in maintaining homeostasis. The effects vary among individuals of a species and between species.
A lot is still unknown about the impact of this emerging disease, and more research is required, such as why susceptibility varies, the pain involved, or the cytology of the disease. Ultimately, it has a huge impact on amphibian biodiversity and populations, and has caused local extinctions.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 10 of):
| 10 |
During the 2024 Olympic Games in Paris, the cleanliness of the River Seine was of concern. High levels of the bacteria Escherichia coli (E. coli) were detected in the river, presenting potential health risks for the athletes competing in the triathlon and open-water swimming events. Several athletes were treated for E. coli infections.
Contrast three features of bacteria and viruses.
Reveal Answer
Answers could include:
- Bacteria are unicellular and living, whereas viruses are non-living.
- Most bacteria are non-pathogenic, but all viruses are pathogenic.
- Bacteria contain DNA or DNA plasmids, whereas viruses contain DNA or RNA.
- Furthermore, bacteria are surrounded by a cell membrane or cell wall, whereas viruses are surrounded by a protein coat.
- Bacteria replicate independently, while viruses replicate within a host cell.
- Finally, bacteria are visible under a light microscope, whereas viruses are too small to be seen under a light microscope.
| Descriptor | Marks |
|---|---|
Any 3 of the following (2 marks each)
| 6 |
In addition to severe nausea, the unwell swimmers started feeling cold, shivering uncontrollably and were asking for blankets, despite the outside temperatures being warm.
Name and outline the physiological responses the swimmers' bodies were having to the infection.
Reveal Answer
The physiological response is a fever.
During a fever, pyrogens are released, and the hypothalamus resets the internal thermostat to a higher temperature. This causes shivering of skeletal muscles and vasoconstriction of peripheral blood vessels, so body temperature will increase. This helps to inhibit the growth or reproduction of pathogens, and macrophage activity is enhanced, which increases phagocytosis. Eventually the fever will break at the crisis point, causing sweating and vasodilation of peripheral blood vessels as the thermostat is reset to normal.
Name of physiological response
| Descriptor | Marks |
|---|---|
Identifies the physiological response as a fever | 1 |
Outline the physiological response
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 9 of): States that pyrogens are released; Describes that the hypothalamus resets the internal thermostat to a higher temperature; Identifies shivering of skeletal muscles; Identifies vasoconstriction of peripheral blood vessels; States that body temperature will increase; Explains that this inhibits the growth/reproduction of pathogens; Explains that macrophage activity is enhanced/increases phagocytosis; States that eventually the fever will break/reach a crisis point; Identifies that this causes sweating; Identifies vasodilation of peripheral blood vessels; States that the thermostat is reset to normal | 9 |
After swimming in the River Seine, Australian athletes were prescribed antibiotics to prevent an E. coli infection.
Antibiotics can be classified into two groups based on their mode of action. Name these two groups and outline how they fight bacterial infections.
Reveal Answer
Bactericidal antibiotics kill bacteria by changing the structure of the cell wall or cell membrane, or by disrupting an essential enzyme.
Bacteriostatic antibiotics inhibit growth or prevent reproduction by disrupting protein synthesis.
| Descriptor | Marks |
|---|---|
Identifies bactericidal antibiotics | 1 |
Explains that bactericidal antibiotics kill bacteria by changing the structure of the cell wall/cell membrane/disrupting an essential enzyme | 1 |
Identifies bacteriostatic antibiotics | 1 |
Explains that bacteriostatic antibiotics inhibit growth/prevent reproduction by disrupting protein synthesis | 1 |
Mary Mallon was an asymptomatic carrier of the Salmonella typhi bacteria who caused several outbreaks of typhoid fever in the early 1900s. She became known as 'Typhoid Mary' and the story is a famous example of disease transmission and the need for public health measures.
Mary worked as a cook in New York homes, with many people developing typhoid fever while she was employed. She was never sick with the disease herself but was tested and identified as an asymptomatic carrier of the disease. Individuals become infected with typhoid fever from the ingestion of the Salmonella typhi bacteria. It is believed Mary was responsible for as many as 122 cases of the disease.
Bacteria can be treated with either antibiotics or a vaccine.
Given the evidence outlined above, identify the most likely mode of transmission for the typhoid fever pathogen.
Reveal Answer
Ingestion of contaminated food or drink.
| Descriptor | Marks |
|---|---|
Identifies the ingestion of contaminated food or drink | 1 |
Identify the location of the most important external body defence mechanism in preventing the spread of Salmonella typhi and outline two ways in which it prevents pathogens entering the internal environment.
Reveal Answer
The stomach.
Defences include (for example): vomiting to expel bacteria, a high acidic environment in the stomach to kill bacteria.
| Descriptor | Marks |
|---|---|
Identifies the stomach, digestive tract, or mouth | 1 |
1 mark for each correct point (any 2 of):
| 2 |
List two ways in which a fever can help the body fight an invading pathogen.
Reveal Answer
It can inhibit pathogen growth; stimulate tissue repair; enhance white blood cell function; enhance the presentation of antigens to macrophages; and increase the production of antibodies.
(any 2).
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Explain the physiological mechanisms that produce a fever.
Reveal Answer
Pyrogens are produced, causing the hypothalamus to increase the body's set point temperature. The body generates heat through shivering and decreases heat loss from the skin through vasoconstriction of blood vessels to the skin.
| Descriptor | Marks |
|---|---|
States that pyrogens or interleukin-1 are produced | 1 |
Explains that the hypothalamus increases the body's set point temperature | 1 |
Describes that the body generates heat through shivering | 1 |
Describes that the body decreases heat loss from the skin or causes vasoconstriction of blood vessels to the skin | 1 |
Describe the key difference between when a person should be treated with antibiotics and when they should be treated with a vaccine.
Reveal Answer
Antibiotics are taken after a person is already infected, whereas vaccines are administered before infection.
| Descriptor | Marks |
|---|---|
States that antibiotics are taken after a person is already infected | 1 |
States that vaccines are administered before infection | 1 |
Present two separate arguments for whether antibiotics and/or a vaccine is the best method of treating a population exposed to, or at risk of, exposure to a disease such as typhoid fever.
Reveal Answer
Vaccines create memory cells while antibiotics don't, therefore vaccines provide long-term immunity and protection.
Additionally, vaccines establish herd immunity while antibiotics don't, therefore vaccines help protect the population and those who cannot be vaccinated.
| Descriptor | Marks |
|---|---|
2 marks for each correct point (any 2 of):
| 4 |
The bacterium Neisseria meningitidis causes meningococcal disease. N. meningitidis is contagious and transmitted between people via secretions of the nose and throat.
State two roles of neutrophils in an immune response to N. meningitidis.
Reveal Answer
| Descriptor | Marks |
|---|---|
1 mark for each correct point (up to 2 marks). Acceptable roles of neutrophils in an immune response to N. meningitidis include:
| 2 |
Contrast how the adaptive immune system responds to an extracellular pathogen, like N. meningitidis, and an intracellular pathogen, like the influenza virus.
Reveal Answer
- Immune system utilises the humoral response to respond to extracellular pathogens whereas the cell-mediated response responds to intracellular pathogens.
- Humoral response results in the production of plasma cells to produce antibodies whereas the cell-mediated response produces cytotoxic T cells.
- Antibodies make it easier for the immune system to recognise and destroy pathogens via opsonisation whereas cytotoxic T cells induce apoptosis in virally infected cells.
- Cell-mediated response produces T memory cells whereas humoral response produces B memory cells.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (up to 4 marks). Acceptable contrasts between how the adaptive immune system responds to an extracellular pathogen and an intracellular pathogen include:
| 4 |
The pathogen that causes jarrah dieback is a type of protist.
In order to prevent the spread of jarrah dieback, vehicles are banned from driving on some tracks when the soil is wet.
List two structural features of protists that are not found in bacteria.
Reveal Answer
Protists are eukaryotes and membrane-bound organelles.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
List two structural features of protists that are not found in fungi.
Reveal Answer
Protists are usually unicellular and often have flagella.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Explain how this can prevent the spread of jarrah dieback.
Reveal Answer
The disease is spread from plant to plant by spores, which are more active when it is wet. Vehicles pick up more contaminated soil when it is wet, therefore the risk of transmission is greater when the soil is wet. Furthermore, vehicles can spread the disease over a large area.
| Descriptor | Marks |
|---|---|
Identifies that the disease is spread (from plant to plant) by spores/zoospores | 1 |
States that spores/zoospores are more active when it is wet | 1 |
Explains that vehicles pick up more (contaminated) soil when it is wet, therefore the risk of transmission/spread is greater when the soil is wet | 1 |
Describes that vehicles can spread the disease/spores/zoospores over a large area | 1 |
Describe how the tuberculosis pathogen is transmitted to a new host.
Reveal Answer
The pathogen is airborne and a new host inhales the pathogen.
| Descriptor | Marks |
|---|---|
States that the pathogen is in the air/airborne OR affected individuals breathe out the pathogen/droplet | 1 |
States that a new host breathes in/inhales the pathogen | 1 |
Describe the impact that the tuberculosis pathogen has on the host.
Reveal Answer
The pathogen infects the lungs and causes coughing.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 2 of):
| 2 |
Explain how vaccination helps to control the spread of tuberculosis.
Reveal Answer
Vaccination introduces a weakenedversion of a pathogen into the body, which stimulates the production of antibodies. Vaccinated individuals become immune. The higher the proportion of the population that is immune, the greater the protection.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 4 of):
| 4 |
When travellers enter Australia from overseas, they are required to declare all plant and animal matter that they have brought with them. Explain why.
Reveal Answer
This is biosecurity measure that protects the agricultural industry. It stops the introduction of exotic pests found in other countries but not in Australia. Plant and animal matter found to be infected will either be treated with pesticides or insecticides, or destroyed.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 4 of):
| 4 |
A man arrived home feeling unwell. His partner took him to the doctor when he started suffering a fever, sweats and chills. The patient was given an antibiotic to take every day for the following 10 days. The doctor stressed the importance of completing the course of antibiotics even when he started to feel better.
Describe the physiological mechanisms that cause fever.
Reveal Answer
The hypothalamus increases the thermostat setting of the body, making the person feel cold. Pyrogens are released, which are produced by white cells or pathogens. Muscles begin to shiver and blood vessels constrict, and both processes help to drive up body temperature. A macrophage engulfs the pathogen and is stimulated to release cytokines, which enhance the pyrogens.
| Descriptor | Marks |
|---|---|
Award 1 mark for each of the following points, up to a maximum of 8 marks:
| 8 |
Explain how different antibiotics can be used to treat infections.
Reveal Answer
Antibiotics target disease-causing bacteria. They can be broad spectrum, affecting a wide range of bacteria, or narrow spectrum, effective only against specific types of bacteria. Bacteriostatic antibiotics inhibit the growth of bacteria by interfering with protein synthesis. Bactericidal antibiotics destroy bacterial pathogens by targeting cell walls, cell membranes, or metabolic pathways found inside bacteria.
| Descriptor | Marks |
|---|---|
Award 1 mark for each of the following points, up to a maximum of 8 marks:
| 8 |
Explain why the doctor stressed that the full course of antibiotics needed to be taken.
Reveal Answer
Antibiotics gradually reduce the numbers of bacteria, but there will still be a small population of bacteria that remain. If antibiotics are then stopped, the bacteria that persist will increase in number as surviving bacteria reproduce. This means reinfection occurs.
Completing the course also helps to reduce the likelihood of resistance developing.
| Descriptor | Marks |
|---|---|
Award 1 mark for each of the following points, up to a maximum of 4 marks:
| 4 |