Edexcel Biology Scientific Article 2013 possible questions + answers

Questions

1. a) Naked mole rats are thought to be poikilothermic (paragraph 5).  explain what is meant by the term poikiloterm. 

b) Outline the evidence that this is the case.

c) how does a homeothermic mammal respond to an increase in environmental temperature?

d) suggest how temperature sensitivity of enzymes may differ between poikilotherms and homeotherms?

2. Naked mole rats are remarkably long lived rodents, soowing few signs of aging (paragraph 7).  oxidative stress is the leading explanation to how we age. Draw a labelled diagram of the organells responsible for oxidative stress.

3. Oxygen containing free radicals (paragraph 9) are relesased from mitochondiria during aerobic respiration.  

a) Name an oxygen containing free radical.

b) Free radicals are associated with concentrations in mitochondria.  Name the process in respiration which requires a concentration of ions.

c) Eplain in detail how oxidative stress can lead to abnormal cell function and cancer. Focus your answer on how oxidative stress is brought about and the affects it has on proteins and DNA.

d) The primary structure of amino acids is unaffected by free radicals whilst secondary and tertiary are.  Suggest why this might be the case.

4.a)All mammals have the gene p27 that prevents cell overcrowding (paragraph 27) suggest the role played by the protein product of this gene in the cell cycle.

b) Naked mole rats have an additional gene(p16) involved in preventing cell overcrowding. Explain how this reduces the chance of a naked mole rat developing cancer.

5. outline an ethical issue surrounding the pain sensitivity experiments in paragraph 31.

6.Suggest an advantage to naked molle rats in developing resistance to chemical pain.

7.a) Define the term hypoxia

b) suggest why extended hypoxia in mammalian cells often leads to cell death

c) Following hypoxic conditions, a cell may recover to full function.  sate the toxic substance prodced during hypoxia, how it was formed and how a cell breaks down the toxin.

8.a) Suggest…