Biology

Francesco Redi challenged the idea that maggots arose spontaneously from rotting meat. A modern version of his experiment was set up as shown.
Which of the following is correct for this experimental set up?
A. The sealed jar improves the validity of the experiment.
B. The independent variable is whether the meat spoils or not.
C. The use of three jars improves the reliability of the experiment.
D. The dependent variable is the use of different covers for the jars.

Robert Koch produced a set of criteria to establish whether a particular organism is the cause of a disease in an animal. The criteria are listed below but not in the correct order.

1. The microorganism must cause disease when introduced to a healthy experimental animal.
2. The microorganism must be extracted and isolated from the diseased animal and subsequently grown in culture.
3. The microorganism must be extracted from the diseased experimental animal and demonstrated to be the same microorganism that was isolated from the first diseased animal.
4. The microorganism must be found in the diseased animal, and not found in healthy animals.
   Which of the following correctly shows the order of steps required to determine the cause of a particular disease in an animal?
   A. 2, 3, 1, 4
   B. 2, 4, 1, 3
   C. 4, 2, 1, 3
   D. 4, 3, 2, 1

A student designed and conducted a practical investigation to test for the presence of microbes in water and food samples.
Justify a safety precaution required to prevent infection when conducting the investigation.

A student designed and conducted a practical investigation to test for the presence of microbes in water and food samples.
Explain how the student could ensure the reliability of the investigation.

Describe a plant disease and its effect on agricultural production.
Name of plant disease: ..............................

Milk pasteurisation (heating to approximately 70°C) was gradually introduced in America from the early 1900s. The graph shows the number of disease outbreaks in relation to raw (unpasteurised) and pasteurised milk in America from 1900−1975.
Explain the trends observed in the graph. In your response, refer to the role of Pasteur’s work in pasteurisation.

Viruses are
(A) unicellular.
(B) multicellular.
(C) smaller than bacteria.
(D) larger than protists.

Certain diseases can be caused by the ingestion of food contaminated with a pathogen that is a misfolded protein. This type of pathogen is a:
(A) prion
(B) plasmid
(C) parasite
(D) virus

A plant pathologist observed brown spots developing on the leaves of a lemon tree and wanted to determine the cause of the disease. The pathologist suspected the tree was suffering from a bacterial disease, caused by infection with Xanthomonas citri.
Describe the steps a pathologist could use to test the hypothesis that the suspected bacterium is the cause of the disease.

Foot-and-mouth disease, a contagious viral disease for cattle, sheep, goats and pigs, resurfaced in Indonesia in May 2022 after the country had been declared free of it for over 30 years. What makes FMD virus so remarkable is its environmental resistance. It can persist on many inanimate objects, such as equipment used with livestock, people’s clothing and shoes, on the tyres of vehicles and in livestock transport. It can also persist in livestock feed and livestock products, such as meat and hides. There is no cure for FMD.
Outline the possible effects of FMD being spread to Australia.

Outline ONE way that a pathogen can pass from person to person.

The following key can be used to classify some pathogens.
Complete each empty box with an appropriate pathogen.

Jelly Bush honey has been used by Aboriginal Peoples to treat cuts, sores and burns. Recent studies have shown that Jelly Bush honey has a very high level of methylglyoxal which is known to help fight infection.
A scientist wants to test the effectiveness of Jelly Bush honey using agar plates.
Design a safe procedure that the scientist could use in a laboratory to investigate the effectiveness of Jelly Bush honey as a pharmaceutical to inhibit bacterial growth.

Malaria is a disease transmitted by a mosquito vector. There has been no effective vaccine developed. Refer to the maps below to answer Question 30.

Discuss possible reasons for the differences in the distribution of malaria and its vector. Include detailed reference to Map 1 and Map 2.

Which of the following are both non-cellular pathogens?
A. Bacteria and virus.
B. Prion and protozoa.
C. Protozoa and bacteria.
D. Virus and prion.

The human PRNP gene codes for the prion protein. Misfolding of this protein may be the result of ingesting tissue that contains misfolded prion protein or a mutation. Accumulation of misfolded prion protein causes serious diseases such as Creutzfeldt– Jakob disease (CJD).
Which of the following statements best classifies CJD?
A. It is both a genetic disease and an infectious disease.
B. It is a genetic disease only, since it is encoded by a gene.
C. It is not an infectious disease because the prion is non-cellular.
D. It is an infectious disease and the normal prion protein is the pathogen.

A scientist followed Koch’s postulates to confirm that this bacterium was causing diarrhoea in pigs on a local farm.
Complete the boxes in the flowchart provided to show the steps taken by the scientist.

Label TWO features on the diagram below that would help to classify this pathogen as a bacterium. 1 μm

Giardiasis is the most common form of non-bacterial diarrhoea of people in Australia. The adult parasite, Giardia lamblia, responsible for the disease, is shown in the figure below. The adult is a single cell. Its ventral side is flattened and has a shallow depression used as a type of sucker. Giardia lives in the upper part of the intestine (duodenum) of an infected person where it rapidly multiplies. To pass from one human to another it encloses itself in a cyst that passes out in the faeces.
Describe ONE procedure that would be suitable for preventing the spread of Giardia and justify its use.

Agrobacterium tumefaciens is a rod-shaped bacterium found in soil. Its flagella allow it to move through the soil in response to chemicals released by wounded plant cells. Once it enters its plant host, it injects a section of its DNA called the T-DNA which is derived from its Ti (tumour inducing) plasmid into its host causing the host to form undifferentiated (tumour) tissue termed a crown gall. Figure 1: Crown gall The interaction between a plant and Agrobacterium is detailed below: (A) Agrobacteria cells produce the hormones cytokinin and auxin, which increase host susceptibility and inhibit H2O2 production and hypersensitive response (HR) upon infection. (B) After integration of the bacterial T-DNA into the plant genome, cytokinin and auxin are synthesized by T-DNA encoded enzymes and accumulate inside the tumour. (C) This causes massive changes in the gene expression pattern resulting in metabolomic and morphological adaptations that are necessary for tumour growth and differentiation. (D) Loss of water is minimized by an increase in the levels of the stress hormone ABA. Evaporation of water from the disrupted crown gall surface drives the flow of water and minerals into crown galls. (E) Because photosynthesis is downregulated, the O2 levels are low, the tumour produces C and N compounds heterotrophically and gains energy mainly anaerobically by alcoholic fermentation. (F) The developing tumour becomes a metabolic sink for the host plant, which accumulates metabolites produced by source leaves and minerals taken up by the roots. (G) Auxin and cytokinin also cause an increase in ethylene (ET) which together with salicylic acid (SA) inhibits agrobacterial virulence. (H) ABA induces DNA methylation of the plant genome, regulating gene expression of drought- stress responsive genes. The oncogenes of the T-DNA remain unaffected by methylation of the plant genome.

Describe ONE adaptation that makes agrobacterium a successful pathogen of plants.

Rubella is an infectious disease caused by Rubivirus rubella. The disease is frequently mild, with a characteristic rash often appearing two weeks after exposure and lasting for three days. Other symptoms include fever, sore throat and fatigue, with joint pain common in adults. Up to half of infected cases are asymptomatic. Rubella is usually spread from one person to the next through the air via coughs of people who are infected. People are infectious during the week before and after the appearance of the rash. Only humans are infected. Once recovered, people are immune to future infections. In the early 1940s, Australian ophthalmologist Norman Gregg noticed a high incidence of congenital cataracts in babies whose mothers had suffered from rubella during pregnancy. It was then statistically shown that infection during early pregnancy may result in a miscarriage or a child born with congenital rubella syndrome (CRS). The main defects result almost exclusively from rubella infection occurring in the first 16 weeks of gestation and include deafness due to cochlea malformation, eye and cardiovascular defects and central nervous system damage leading to mental retardation. Rubella is preventable with a single dose of the rubella vaccine being more than 95% effective. When rubella vaccination became feasible around 1971, both the United States and the United Kingdom embarked on vaccination programs. In the United States, the strategy was to vaccinate infants, so that eventually the reservoir in childhood would be abolished. In contrast, the United Kingdom decided on a program of vaccinating adolescent girls. Both strategies were partial successes, in that CRS incidence began to decrease. Figure 1: Number of Rubella and Congenital Rubella Syndrome Cases in the United States 1966-2011
Justify a hypothesis as to why the UK program was only a partial success in reducing the rate of CRS.
Hypothesis:………………………………………………………………………………………
Justification:………………………………………………………………………………………

Malaria is a disease in humans caused by a single-celled Plasmodium species. It is transmitted by female mosquitoes. Which of the following is true for malaria?
A. Both Plasmodium and the mosquito are vectors
B. Both Plasmodium and the mosquito are pathogens
C. The mosquito is the vector and Plasmodium is the pathogen
D. The mosquito is the pathogen and Plasmodium is the vector

Students designed and conducted an investigation to test for the presence of microbes in THREE different food samples. They inoculated agar plates with the samples and placed them in an incubator set to 25°C.
Which row of the table represents a valid design for the investigation?