A patient is undergoing treatment for a brain tumour. The treatment accurately targeted and destroyed the actively growing cells in the tumour by damaging their DNA.
What therapy is used to treat the patient’s brain tumour?
A Chemotherapy
B Hormone-related therapy
C Immunotherapy
D Radiotherapy
Your answer
The table compares the structure of DNA and RNA nucleotides.
Complete the table by writing the names of the structural features present in DNA and RNA.
| Structural feature | DNA | RNA |
| Pentose sugar | ................................................. | ................................................. |
| Purine bases | ................................................. ................................................. | ................................................. ................................................. |
| Pyrimidine bases | ................................................. ................................................. | ................................................. ................................................. |
A section of RNA is represented in the diagram.
Draw a circle around a phosphodiester bond.
Answer on the diagram.
Complete the following passage using the most appropriate words or phrases.
Semi-conservative replication of DNA involves the enzyme........,
which breaks the........ bonds between the two strands.
DNA nucleotides bind to each of the separated strands and the enzyme
........ joins the nucleotides in a
........ reaction to form two new strands.
Describe the role of cell cycle checkpoints in ensuring the accuracy of DNA replication.
Suggest why mutations that affect cell cycle checkpoints can increase the general rate of mutation.
Radiotherapy causes damage to the DNA of cancer cells.
Suggest how this process can reduce the size of a tumour.
Umbilical cord blood can be collected from the placenta after birth.
Umbilical cord blood transplantation can be used as an alternative to bone marrow transplantation.
Suggest the type of potency for the stem cells present in umbilical cord blood.
Suggest one advantage of umbilical cord blood transplantation over bone marrow transplantation.
Tumour formation is the result of uncontrolled mitosis.
Uncontrolled mitosis can occur when processes that regulate mitosis and the cell cycle stop functioning.
Cancer treatments often target these processes.
The diagram shows a cell with two pairs of chromosomes.
In the space below, draw an annotated diagram of this cell in the anaphase stage of mitosis.
Indicate the features that show the cell is in anaphase.
Discuss the advantages and disadvantages of the use of plants as sources of anti-cancer drugs.
Paclitaxel and topotecan are two anti-cancer drugs. Both drugs were initially isolated from natural sources.
Paclitaxel interferes with microtubule formation during cell division.
Topotecan causes breaks in the DNA double strand during DNA replication.
Researchers carried out a clinical trial to compare the efficacy of paclitaxel and topotecan.
They selected patients with advanced epithelial ovarian cancer who had not responded to previous anti-cancer treatments.
The patients were then treated with either paclitaxel or topotecan.
Describe how patients would be assigned to the two treatment groups and explain why they were assigned in this way.
The results of the clinical trial are shown in the table.
| Paclitaxel group | Topotecan group | Statistical significance | |
| Median time to progression of disease (weeks) | 14 | 23 | p = 0.002 |
| Median survival (weeks) | 43 | 61 | p = 0.515 |
The researchers concluded that topotecan has efficacy at least equivalent to that of paclitaxel.
Explain why the researchers reached this conclusion.
Other researchers have proposed that paclitaxel and topotecan could be more effective if they are used at the same time in a combined treatment of advanced cancers.
Suggest why the two drugs may be more effective when used together in a combined treatment.
Also involves The immune system · Monoclonal antibodies
This question is based on the Advance Notice Article ‘Development of therapeutic antibodies for the treatment of disease’.
State what is meant by the term antigen.
Scientists can combine antibody fragments using phage display to produce many different antibodies, each specific to a different antigen.
Using the abbreviations from Fig. 1 in the Advance Notice Article, explain how combining antibody fragments allows scientists to produce many different antibodies, each specific to a different antigen.
The B cell receptor is an IgG molecule with the same structure as the human IgG shown in Fig. 1 in the Advance Notice Article.
Use an abbreviation from Fig. 1 to identify the part of the B cell receptor that will be attached to the cell surface membrane of a B cell.
Explain why mouse monoclonal antibodies (mAbs) have been largely replaced as therapeutic antibodies by humanised or fully human mAbs.
Explain why the Fab and scFv antibody fragments shown in Fig. 1 are effective as neutralizing or agglutinating antibodies but are less effective as opsonins or in activation of complement.
Describe how therapeutic mAbs can be used in cancer treatment.
The cost of treating a patient with advanced cancer using therapeutic mAbs can be extremely high. In some cases, the treatment can increase survival time by just a few months.
Pharmaceutical companies justify the high cost of treatment based on the high costs of developing and testing therapeutic mAbs.
Discuss whether the use of therapeutic mAbs to treat cancer justifies the high costs.
* Describe the role of T and B lymphocytes in the development of long-term immunity.
Additional answer space if required.
The faecal occult blood test (FOBT) is a screening method that is now used routinely in people over the age of 65 years.
The presence of blood in faeces (a positive result) is thought to be caused by chronic inflammation of the gut and indicates an increased risk of developing colorectal cancer (CRC).
A Scottish study looked at 133 921 individuals who were tested with FOBT and then followed for up to 16 years.
• 131 207 had a negative FOBT
• 2714 had a positive FOBT
Outline a method that a doctor could use to confirm that a person with a positive FOBT has CRC.
An FOBT kit is sent to everyone in England between 60 and 74 years of age.
Using your own knowledge and the data in the graphs, evaluate the effectiveness of FOBT in screening for CRC.
* CRC is one of more than 100 forms of cancer.
Describe, with examples, how mutations in genes that control cell division can lead to cancer.
Additional answer space if required.
There is evidence that heart rate increases when people experience pain. Heart rate is one physiological factor that is regulated tightly and kept within narrow limits.
Name the process by which the internal environment of an organism is kept within narrow limits.
A student made the following revision notes about the control of heart rate.
Complete the student’s notes using the most appropriate word(s).
‘The resting heart rate of an adult human is about 70 beats per minute. This is
known as the set point. There are two types of receptor that control heart
rate: ………………………………………………… in the walls of the carotid artery that detect
changes in blood pH and pressure receptors in the carotid artery and the
aorta. When blood pressure rises, pressure receptors transmit nervous impulses
to the ……………………………………………………… which decreases heart rate via the
……………………………………………………… nervous system. This is an example of
Some doctors who study pain ask patients to give an estimate of the level of their pain by using a scale of 1 to 10.
Explain why some researchers think that measuring heart rate is a more accurate way of determining the level of pain.
Neuropathic pain is a type of pain caused by neurones malfunctioning following nerve damage. When this happens, some voltage-gated sodium ion channels (VGSCs) in pain receptors open spontaneously.
Explain how the spontaneous opening of a VGSC in a pain receptor leads to the generation of a nerve impulse in the sensory neurone attached to the pain receptor.
Three different types of VGSC in different parts of the nervous system have been linked to neuropathic pain. Drugs to treat neuropathic pain are now being developed that specifically block these types of VGSC.
Suggest why it is important to develop drugs that only block these three types of VGSC.
Single nucleotide polymorphisms (SNPs) have been detected in the genes coding for several types of VGSC. It is thought that these SNPs might alter the response of different patients to drugs that block VGSCs.
Describe the steps involved in identifying the SNPs present in a DNA sample from a patient.
Screening for other SNPs is used in the study, diagnosis, and treatment of cancer.
A mutation in either the BRCA1 or BRCA2 gene increases the risk of breast cancer.
Explain why screening for these mutations is only offered to individuals with a strong family history of breast cancer and a living relative with breast cancer.
Fig. 4 shows a simplified diagram of part of a DNA molecule.
Fig. 4
Identify the parts of the DNA molecule labelled A to C in Fig. 4.
The table below shows the results of an analysis of the base composition for each strand of a DNA molecule.
Complete the table by adding the missing values for strands 1 and 2.
Hydrogen bonding is central to the function of nucleic acids.
Explain how hydrogen bonding contributes to the process of semi-conservative replication of DNA.
Hereditary non-polyposis colorectal cancer (HNPCC) is a type of bowel cancer caused by a mutation in genes that normally repair DNA.
Explain why mutations in DNA repair genes lead to development of cancer in the bowel and other organs.
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