How many VCAA Biology questions cover How do organisms respond to pathogens??

AusGrader has 86 VCAA Biology questions on How do organisms respond to pathogens?, all with instant AI grading and detailed marking feedback.

VCAA Biology How do organisms respond to pathogens?

5 sample questions with marking guides and sample answers

Q17

2020

SCSA

1 mark

Q17

1 mark

Climate change is affecting the distribution of Ross River virus through its effects on activity and reproduction in the

viral pathogen.

bacterial pathogen.

human host.

mosquito vector.

Q20

2020

SCSA

1 mark

Q20

1 mark

Antibiotics are ineffective against viruses because viruses

keep changing their external protein coat.

are able to disguise themselves in the host cell membrane.

are not living cells and thus do not metabolise.

can change antibiotics into useful food substances.

Q39

2024

SCSA

20 marks

Q39

Crown gall is an infectious disease of plants that can cause significant economic losses.

Q39a

10 marks

For crown gall disease, explain how the pathogen invades the host and causes disease, and two distinctly different management strategies to prevent the spread of the disease.

The pathogen invade the host and cause disease by first invading the plant through a wound, and inserting plasmid into the host genome. This causes rapid division of host cells, causing galls. Galls disrupt water transport, reducing the ability of plants to resist stressful conditions such as drought.

Management strategies are (any 2 of):

Avoid damaging the plants, to stop transfer of pathogen from one plant to another.
Destroy infected plants, to kill bacteria in the environment.
Apply biosecurity measures at borders, to contain the disease to a certain area.
Educate people, so people can recognise the disease and act quickly.

Marking Criteria

How the pathogen invades the host and causes disease

Descriptor	Marks
1 mark for each correct point: bacterium/pathogen invades the plant through a wound inserts plasmid into host genome; causes rapid division of host cells causes galls (where the roots join the trunk, on the roots, or on the main stem or branches) galls disrupt water transport reduces ability of plants to resist stressful conditions such as drought	6

Management strategy 1

Marking Bands

Descriptor	Marks
Identifies a management strategy and explains its purpose (e.g., do not damage plants/clean tools to stop transfer; destroy infected plants to kill/reduce bacteria; apply biosecurity to contain disease; educate people so they can recognise/act)	2
Identifies a management strategy OR its purpose	1
None of the above	0

Management strategy 2

Marking Bands

Descriptor	Marks
Identifies a management strategy and explains its purpose (e.g., do not damage plants/clean tools to stop transfer; destroy infected plants to kill/reduce bacteria; apply biosecurity to contain disease; educate people so they can recognise/act)	2
Identifies a management strategy OR its purpose	1
None of the above	0

Q39b

10 marks

Animals have a variety of behavioural, physiological and structural adaptations to maintain water and salt balance.

Explain what would happen to a desert mammal if it drank saltwater and explain one physiological and one behavioural adaptation that desert mammals use to maintain water-salt balance. State which adaption is physiological and which is behavioural.

Drinking salt water disrupts homeostasis, as body fluids will have too much salt. Cells will lose water to body fluids by osmosis, making them dehydrate.

A physiological adaptation is (insert relevant example). This helps maintain water-salt balance by (any 1 of the following):

gaining water from food metabolism, where breakdown of fat produces water
producing hormones, which promote reabsorption of water by the kidneys

A behavioural adaptation is (insert relevant example). This helps maintain water-salt balance by (any 1 of the following):

being active at night when temperatures are lower, to minimise water loss by evaporation
burrowing creates humid microclimate to minimise water loss by evaporation

Marking Criteria

Effects of drinking salt water

Descriptor	Marks
1 mark for each correct point (any 4 of): disrupts homeostasis/osmoregulation/osmosis body fluids will have too much salt/hypertonic to cells or cells will be hypotonic to body fluids cells will lose water to body fluids (by osmosis) cells will shrink/wrinkle/dehydrate lack of water/high concentration of solutes will disrupt metabolic processes	4

Explanation of physiological adaptations

Marking Bands

Descriptor	Marks
States a physiological adaptation AND provides a complete explanation (e.g., gains water from food metabolism by breaking down fat/carbohydrates OR produces hormone/vasopressin/antidiuretic to promote reabsorption of water by kidney)	3
States a physiological adaptation AND provides a partial explanation	2
States a physiological adaptation	1
None of the above	0

Explanation of behavioural adaptations

Marking Bands

Descriptor	Marks
States a behavioural adaptation AND provides a complete explanation (e.g., nocturnal/active at night when temperatures are lower to minimise water loss by evaporation OR burrows to create humid microclimate/avoid high temperatures to minimise water loss by evaporation)	3
States a behavioural adaptation AND provides a partial explanation	2
States a behavioural adaptation	1
None of the above	0

Q38

2024

SCSA

20 marks

Q38

Xerophytic plants need to maintain water balance while allowing for gas exchange, and have a variety of adaptations to achieve this.

Q38a

10 marks

Explain why plants lose water to the environment during gas exchange and three distinctly different ways in which xerophytic plants minimise water loss from gas exchange.

Gas exchange occurs through stomata, which are pores in the leaf. When stomata are open, water is lost from the plant via transpiration/evaporation.

Ways to minimise water loss from gas exchange are (any 3 of):

Reduced stomata size, such that there's smaller area to lose water through.
Sunken stomata, which increases humidity around stomatal pore.
Closing stomata during the day, when temperatures are higher.
Rolled leaves, which protect stomata from the environment.

Marking Criteria

Water loss during gas exchange

Descriptor	Marks
gas exchange occurs through (open) stomata or plants release oxygen/take in carbon dioxide through (open) stomata	1
stomata are pores in the leaf (that are surrounded by guard cells)	1
water/water vapour is lost from plant when stomata are open	1
via transpiration or evaporation	1

Minimising water loss 1

Descriptor	Marks
Identifies a valid strategy to minimise water loss (e.g., fewer stomata/reduced size, sunken stomata/hairs in pit/rolled leaves, stomata open at night/close during day, less stomata on upper surface/more on lower surface)	1
Provides the corresponding explanation for how the identified strategy minimises water loss (e.g., fewer openings/smaller area, increases humidity/creates humid microclimate, open when temperatures are lower, protects stomata from environment/wind/sunlight)	1

Minimising water loss 2

Descriptor	Marks
Identifies a valid strategy to minimise water loss (e.g., fewer stomata/reduced size, sunken stomata/hairs in pit/rolled leaves, stomata open at night/close during day, less stomata on upper surface/more on lower surface)	1
Provides the corresponding explanation for how the identified strategy minimises water loss (e.g., fewer openings/smaller area, increases humidity/creates humid microclimate, open when temperatures are lower, protects stomata from environment/wind/sunlight)	1

Minimising water loss 3

Descriptor	Marks
Identifies a valid strategy to minimise water loss (e.g., fewer stomata/reduced size, sunken stomata/hairs in pit/rolled leaves, stomata open at night/close during day, less stomata on upper surface/more on lower surface)	1
Provides the corresponding explanation for how the identified strategy minimises water loss (e.g., fewer openings/smaller area, increases humidity/creates humid microclimate, open when temperatures are lower, protects stomata from environment/wind/sunlight)	1

Q38b

10 marks

The chance of an epidemic occurring depends on several factors.

Using influenza as an example, explain why urban areas are susceptible to epidemics and how vaccination and three other healthcare provisions can reduce disease transmission.

Influenza is easily spread via direct contact or airborne particles. Urban areas have high population density, which increases disease transmission, as uninfected people are more likely to come into contact with an infected person. Increased travel to urban areas also increases the chance of introducing a new strain with little resistance in the population.

Vaccines give people immunity without catching the disease, which reduces the chances of an individual catching the disease even if they are in contact with an infected individual. The spread of disease will slow if a large proportion of the population are vaccinated.

Other healthcare provisions include education about good hygiene. Healthcare can implement quarantine of infected people, and provide antiviral medication to reduce the severity and duration of symptoms. Monitoring and reporting can result in early detection and early implementation of control measures.

Marking Criteria

Urban areas

Descriptor	Marks
1 mark for each correct point (any 4 of): • Identifies that influenza is easily spread or transmitted via direct contact or airborne particles • States that urban areas have high population density • Explains that high density increases disease/influenza transmission • Describes that uninfected people are more likely to come into contact with an infected person • Explains that increased travel/migration to urban areas increases the chance of introducing a new strain (little resistance in population)	4

Descriptor

Marks

1 mark for each correct point (any 4 of):
• Identifies that influenza is easily spread or transmitted via direct contact or airborne particles
• States that urban areas have high population density
• Explains that high density increases disease/influenza transmission
• Describes that uninfected people are more likely to come into contact with an infected person
• Explains that increased travel/migration to urban areas increases the chance of introducing a new strain (little resistance in population)

Vaccinations

Descriptor	Marks
States that vaccines give people immunity (without catching the disease)	1
Explains that vaccination reduces the chances of an individual catching the disease (even if they are in contact with an infected individual)	1
Describes that the spread of disease will slow/transmission will be reduced if a large proportion of the population are vaccinated/immune/with herd immunity	1

Other healthcare provisions

Descriptor	Marks
1 mark for each correct point (any 3 of): Identifies education/advice about good hygiene/mask wearing/hand washing States that isolation/quarantine of infected people can be implemented Identifies antiviral medication to reduce severity/duration of symptoms Describes how monitoring/reporting can result in early detection/early implementation of control measures	3

Q34

2025

SCSA

20 marks

Q34c

The major groups of organisms that cause infectious disease are bacteria, fungi, protists and viruses. Two new chemical treatments have been developed for treating some infectious diseases. Treatment A acts by destroying chitin molecules. Treatment B acts by destroying cellulose molecules.

Q34a

4 marks

Identify two errors in the following statement about crown gall disease and, in each case, justify your answer.

Crown gall is a viral, waterborne disease of plants.

Error 1: stating that crown gall is a viral disease -- crown gall is caused by a bacterium.

Error 2: stating that crown gall is a waterborne disease -- crown gall is a soilborne disease and is transmitted through contaminated soil or equipment.

Marking Criteria

Descriptor	Marks
Identifies the first error as stating crown gall is a viral disease	1
Justifies this by stating crown gall is caused by a bacterium	1
Identifies the second error as stating crown gall is a waterborne disease	1
Justifies this by stating crown gall is a soilborne disease or is transmitted through contaminated soil or equipment	1

Q34b

4 marks

Describe how the crown gall pathogen causes disease.

The pathogen DNA is inserted into the host genome, and this inserted DNA contains hormone genes. These genes cause rapid cell division, which disrupt the transport of water and nutrients. The galls divert energy from normal growth in the host, hence plant growth slows.

Marking Criteria

Descriptor	Marks
1 mark for each correct point (any 4 of): Describes that pathogen DNA/plasmid is inserted into the host genome; States that the inserted DNA/plasmid contains hormone genes; Explains that these genes cause excessive/rapid cell division or galls in the host; States that this disrupts the transport of water/nutrients; Explains that galls divert energy from normal growth in the host; Concludes that plant growth slows, the plant wilts, productivity is reduced, plants are less able to tolerate stressful conditions, or plants die/are unhealthy	4

Descriptor

Marks

1 mark for each correct point (any 4 of):
Describes that pathogen DNA/plasmid is inserted into the host genome; States that the inserted DNA/plasmid contains hormone genes;
Explains that these genes cause excessive/rapid cell division or galls in the host;
States that this disrupts the transport of water/nutrients;
Explains that galls divert energy from normal growth in the host;
Concludes that plant growth slows, the plant wilts, productivity is reduced, plants are less able to tolerate stressful conditions, or plants die/are unhealthy

Q34c (i)

1 mark

State one pathogen group that might be harmed by Treatment A.

Descriptor	Marks
Identifies fungi	1

Q34c (ii)

2 marks

Outline how Treatment A might harm the pathogen group stated in part (c)(i).

Chitin is present in fungal cell walls, so the treatment will destroy the cell walls.

Marking Criteria

Descriptor	Marks
States that chitin is present in fungal cell walls	1
Explains that the treatment will destroy the cell walls, cause cells to rupture, or kill the cells	1

Q34c (iii)

3 marks

Evaluate whether Treatment A might be an effective treatment for Phytophthora dieback in plants.

It would be ineffective because the Phytophthora pathogen is a protist and it does not have chitin in its cell wall.

Marking Criteria

Descriptor	Marks
Clearly states that the treatment is ineffective	1
Identifies that the Phytophthora pathogen is a protist	1
Explains that it does not have chitin in its cell wall	1

Q34c (iv)

3 marks

Evaluate whether Treatment B might be an effective treatment for Phytophthora dieback in plants.

It would be ineffective because both the Phytophthora pathogen and the plant host have cellulose in their cell walls. The treatment would therefore harm or kill the host plant as well.

Marking Criteria

Descriptor	Marks
Clearly states that the treatment is ineffective	1
Identifies that both the Phytophthora pathogen and the plant host have cellulose in their cell walls	1
Explains that the treatment would therefore harm or kill the host plant as well	1

Q34d

3 marks

Health departments across Australia recommend that owners of rainwater tanks install mesh netting on all inlets and outlets of the tank.

Explain how mesh netting installed on tank inlets and outlets can assist in controlling the spread of Ross River fever.

Ross River fever is transmitted by mosquitoes, and mosquitoes can breed in tanks. The mesh stops the mosquitoes from entering the tank and disrupts the life cycle of the mosquito.

Marking Criteria

Descriptor	Marks
States that Ross River fever is transmitted by mosquitoes	1
Identifies that mosquitoes can breed in tanks	1
Explains that mesh/netting stops mosquitoes entering the tank or disrupts the life cycle of the mosquito/pathogen	1

VCAA Biology How do organisms respond to pathogens?

How the pathogen invades the host and causes disease

Management strategy 1

Management strategy 2

Effects of drinking salt water

Explanation of physiological adaptations

Explanation of behavioural adaptations

Water loss during gas exchange

Minimising water loss 1

Minimising water loss 2

Minimising water loss 3

Urban areas

Vaccinations

Other healthcare provisions

Frequently Asked Questions

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