Biology

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

The graph below shows the relationship between body temperature and environmental temperature of 4 different organisms. Which of the following statements is best supported by the data?
A. Animals I and II are most likely mammals.
B. Animal II is endothermic over the environmental temperature range of 0 to 30°C.
C. Animal III maintains its body core temperature relatively constant by shivering when the environmental temperature falls below 37°C.
D. Animal IV is most likely a mammal in polar region.

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.

Duchenne muscular dystrophy is a genetic disorder, where the muscles waste away due to inadequate production of a protein called dystrophin. A group of researchers isolated the gene for dystrophin and inserted it into a plasmid extracted from a bacterium. A concentrated solution of these recombinant plasmids was then injected into the muscles of mice with a missense mutation in the gene for dystrophin. Which of the following is the function of the injected plasmid in treating the disorder?
A. To stimulate a humoral immune response to the bacteria in the treated mice.
B. To deliver the dystrophin protein directly to the muscles of the treated mice.
C. To act as a vector for the delivery of dystrophin genes to the muscle cells of the treated mice.
D. To create a strain of genetically engineered bacteria that will cure Duchenne muscular dystrophy.

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.

A pathology centre took blood samples from three patients. One patient was suspected of suffering from anaemia, which reduces the oxygen carrying capacity of the blood. Another patient was suffering from Human immunodeficiency virus (HIV) which attacks T cells. The third patient had a red, raised area following a puncture wound. The table below shows the numbers of different types of blood cells found in blood samples taken from the three patients.

Which of the following correctly matches the patient to the condition?

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

Over millions of years of evolution, mutations occur at a broadly constant rate within a gene. This allows genes to be used as molecular clocks. The diagram below shows how the base sequence in part of a gene changed as two evolutionary lineages diverged from an original base sequence. Assuming this rate of mutation continued, by how many bases would this part of the gene differ in Species X compared with Species Y 20 million years after diverging from the original base sequence?
A. 4
B. 8
C. 16
D. 20

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.

Which of the following statements best explains why bacteria are used in gene cloning?
A. Bacteria can replicate non-bacterial sequences of DNA in a short time.
B. Bacteria allow the entry of foreign DNA into their nuclei.
C. Bacteria replicate exponentially by undergoing mitotic divisions.
D. Bacteria contain restriction enzymes that randomly cut chromosomes into fragments of varying size.

The diagram shows a bacterial plasmid with restriction sites for three different restriction endonucleases, Sal 1, Eco R1 and Bam H1. Which row in the table identifies the number of fragments produced if the plasmid was cut with the combinations of restriction endonucleases shown?

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?

Consider the following steps taking place in the cell cycle:
I. Re-formation of nuclear membranes
II. Pairing of homologous chromosomes
III. DNA replication
Which of these take(s) place during either interphase or mitosis in animal cells?
A. I only
B. I and II only
C. II and III only
D. I and III only

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.

Osmoregulation is the process by which water and salt (or solute) concentration in the blood achieves homeostasis using aldosterone and anti-diuretic hormones (ADH). Aldosterone acts on sodium ions causing them to be actively reabsorbed back into the blood from the kidney. As a result, the blood in the capillaries surrounding the kidney’s distal tubule will have a higher solute concentration. An increase in solute concentration in the blood causes the pituitary gland to secrete ADH into the blood stream to increase their permeability of distal tubules to water. This increases the amount of water reabsorbed back into the blood from the kidney. The amount of ADH secreted will decrease when the solute concentration in the blood returns to normality establishing osmoregulation.
A dehydrated marathon runner consumed a concentrated salt sports drink to satisfy his thirst.
How does his body control the two hormones, ADH and aldosterone, to help to re- establish normal water balance?
A. ADH is released and aldosterone is inhibited
B. ADH is inhibited and aldosterone is released.
C. Both ADH and aldosterone are released.
D. Both ADH and aldosterone are inhibited.

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.

Adrenocorticotropic hormone (ACTH) is the hormone that stimulates cholesterol conversion to progesterone and testosterone. Progesterone is then converted to cortisol due to the action of an enzyme 21-hydroxylase. If the enzyme is defective, the synthesis of cortisol is reduced, and an excess of testosterone is produced. This results in a disorder called congenital adrenal hyperplasia (CAH).
To diagnose CAH disorder, an ACTH stimulation test is performed. Blood is measured for starting levels of testosterone. ACTH is then injected, and another blood sample is taken and analysed after 120 minutes.
Using the given key which of the following graphs best depicts the changes in the level of testosterone in an ACTH stimulation test?

The following events occur after DNA is subjected to radiation. The events are listed in no specific order. W: Mutation X: Change in cell activity Y: Change in protein structure Z: Change in polypeptide sequence What is the correct sequence of steps?
A. W, X, Y, Z
B. Z, X, W, Y
C. Z, Y, X, W
D. W, Z, Y, X

In a separate experiment, cells are treated with a chemical mutagen that causes only nucleotide substitutions in DNA. Which of the following is the most correct prediction for the result of a comet assay for this treatment?
A. The tail will be longer than a cell with double-stranded breaks in DNA.
B. The head will remain in place and the tail will move towards the negative terminal.
C. The only visible part will be the head with no tail.
D. There will be no visible head or tail.

Which of the following is correct about the genotype of the identified individual?
A. I–1 is type 1.
B. II–2 is type 2.
C. III–2 is type 3.
D. III–12 is type 4.

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.