Paper 3 Bio Flashcards
EQ. Describe how a tumour can move to other parts of the body. (2 marks)
-cells from tumours break off -travel in the blood to other organs
EQ. Explain how natural selection has ensured ‘different finch species….evolved on each island’. (6 marks)
- allopatric speciation
- there is variation within each population
- so they can no longer interbreed to produce fertile offspring
- due to mutations
- because of different selection pressures
- different alleles are advantageous
- those with advantageous alleles survive and pass them on
- frequency increases
Describe how inflammation can lead to ‘tissue alteration’. (4 marks)
- histamines released from mast cells
- vasodilation increases blood flow
- increase in tissue fluid + plasma
- this causes swelling, redness and pain
Explain how chemicals in Cigarette smoke might affect the cell cycle. (3 marks)
- chemicals affect methylation
- affects DNA that acts as a transcription factor for oncogenes
- transcriprion is blocked
- cell division is not controlled
Give 2 ethical arguments for the use of mice in cancer drug tests. (2 marks)
- only done when necessary and scientists follow strict rules
- people think humans have a greater right to life because we have more complex brains
Define stem cell. (2 marks)
An undifferentiated cell that can give rise to specialised cells
Suggest why people with leukemia(non functioning lymphocytes) are prone to recurrent infections. (2 marks)
- lymphocytes include B cells and T cells
- important in the production of antibiodies and the specific immune response
Deduce how the ‘Maximum tolerated dose - MTD’ could be found (3 marks)
- use clinical trials
- test on infected patients
- use double blind with placebo to prevent bias
- look for tumour shrinkage
Describe the steps that would be involved in the authors publishing the findings of their research. (2 marks)
- submit the report to scientific journals
- experts in field peer review report
- check the reliability and validity of experiments
