Biology

Identify two structural barriers that can reduce the entry of pathogens into an organism.

Explain how transmission pathways influence strategies used to control an infectious disease.

Describe the roles of two types of white blood cell during an immune response.

Explain why a secondary immune response is usually faster than a primary immune response.

Assess how a coordinated public health response can limit the impact of an emerging infectious disease.

A patient felt tired, weak and had a swollen neck. After following the doctor’s advice to eat more foods containing iodised salt, her symptoms disappeared.
What was the most likely cause of the patient’s symptoms?
A. Cancer
B. Genetic disorder
C. Nutritional deficiency
D. Environmental exposure

Which of the following photographs shows an example of sexual reproduction?

A scientist transferred male gametes from one plant to another to achieve a desired characteristic in the offspring. Which genetic technology was the scientist using?
A. Gene cloning
B. Artificial pollination
C. Artificial insemination
D. Whole organism cloning

Which is the most effective strategy for treating non-infectious diseases? A. Hygiene B. Pharmaceuticals C. Quarantine D. Vaccination

Glucose levels are maintained by the hormones insulin and glucagon. Which statement best describes the changes in hormone levels of a healthy human soon after a high glucose meal? A. Insulin levels fall and glucagon levels rise. B. Insulin levels fall and glucagon levels fall. C. Insulin levels rise and glucagon levels fall. D. Insulin levels rise and glucagon levels rise.

A mutation involving a DNA deletion is illustrated. Which statement about the mutation is correct? A. It will have an effect on many genes. B. It will have an effect on only one codon. C. It may be the result of an error during translation. D. It may be the result of an error during transcription.

Which of the following shows correct base pairing in DNA replication?
A. AATGTGCCA UUACACGGU
B. AATGTGCCA GGCACATTG
C. AATGTGCCA TTACACGGT
D. AATGTGCCA TTUCUCGGT

Howard Florey conducted a breakthrough experiment in the development and use of antibiotics. He infected eight mice with Streptococcus bacteria. Four mice were given penicillin and survived while the four untreated mice died. What conclusion could be drawn from the data obtained?
A. The experiment should be repeated with more mice.
B. The use of penicillin causes antibiotic resistance in mice.
C. Penicillin may be used on humans safely to treat bacterial infections.
D. Penicillin may have played a role in the survival of the four treated mice.

Streptomycin is an antibiotic that kills bacteria by interfering with the function of their ribosomes. The primary effect of the antibiotic is that it prevents the bacteria from producing
A. tRNA.
B. mRNA.
C. amino acids.
D. polypeptides.

Cystic fibrosis is an autosomal recessive disorder caused by mutations in the CFTR gene. Many different recessive alleles cause cystic fibrosis. The four most common alleles of the CFTR gene and their frequencies in the Australian population are shown in the table. What will be the most common genotype of cystic fibrosis patients in Australia?
A. a1/a1
B. a1/a2
C. A/a1
D. A/A

Many transgenic crops have been genetically engineered to have traits such as herbicide resistance. In at least four different crops the transgene has been found in nearby wild plant relatives of the cultivated crops. What is the most likely reason for this observation?
A. Crossing over in the wild plants
B. Gene flow from the crops to the wild plants
C. Genetic drift from the crops to the wild plants
D. Mutations in the wild plants that match the transgenes

The graph shows the levels of three hormones, oestrogen, progesterone and human chorionic gonadotrophin (HCG), measured in the blood of a woman during her pregnancy.
Which statement can be inferred from the graph?
A. Birth occurred about week 36.
B. Fertilisation occurred at day 0.
C. Implantation occurred about week 4.
D. The placenta was formed about week 24.

The photographs show an open and a closed stomate on a leaf surface. When open, stomates allow water vapour to pass out of the leaf. Regulating stomates is a mechanism by which plants maintain water balance. Which of the following graphs best illustrates this homeostatic mechanism?

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.

An example of the mutagenic effect of ultraviolet radiation (UV) on DNA is shown in the diagram. What is the mutagenic effect that is modelled?
A. Thymine is duplicated.
B. Bonds are formed between adjacent bases.
C. Nucleotides form bonds in the backbone of DNA.
D. Thymines on the two strands of DNA form bonds.

Scientists conducted an experiment to investigate the effectiveness of treating water from storage dams with UV radiation.
The experiment was conducted more than three times. The results are shown in the table.
What conclusion may be drawn from the data obtained?
A. The control plates are contaminated.
B. High doses of UV eliminate all pathogens.
C. Exposure to UV inhibits reproduction of bacteria.
D. The presence of bacteria reduces the amount of UV.

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

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.

Two pig farmers on neighbouring farms noticed that their pigs were suffering from diarrhoea and gradually losing weight. The farmers each adopted a different strategy to deal with this disease, as shown in the table. Outline ONE benefit and ONE limitation of the strategies used on each farm.

In a population of rabbits, black fur colour is dominant over white fur. A black rabbit, whose mother has white fur, mates with a white rabbit. Predict the phenotypic ratio for the offspring of this cross. Show your working.