Teaching Ideas for Option F

Cambridge Biology for the IB Diploma

Teaching ideas for Option F, Microbes and biotechnology

This is a diverse option that includes aspects of health, ecology, food technology and biotechnology. The positive roles of microbes in the environment can be contrasted with the problems that some of them cause in human disease. The vast range of microbes makes them potentially useful in the future for bioremediation and production of biofuels.

Practical activities

• Supply students with yoghurt, buttermilk or sour cream to carry out the Gram stain procedure. Yoghurt contains two types of bacteria – chains of cocci or diplococci (Streptococcus thermophilus) and rod-shaped bacilli (either Lactobacillus acidophilus or L. bulgaricus). The bacteria will be Gram positive (staining purple) and the milk protein casein will stain pink.

• Ask students to research the use of reed bed filters to treat sewage, and the use of biomass to produce biofuels, as alternative, ‘environmentally friendly’ human activities. They can also research the worldwide use of biofuels and their potential for the future.

• Supply students with the necessary ingredients and ask them to prepare bread dough that rises to the greatest height (or volume). This can be used as the basis of an assessed practical in which students consider the optimum conditions for yeast activity. Students may also like to brew non-alcoholic ginger beer to investigate aerobic activity of yeast. A recipe can be found on the following site:
http://www.scienceinschool.org/2008/issue8/gingerbeer

• Students can investigate food preservation on a small scale using frozen peas. A few peas in test tubes can be exposed to different sugar and salt concentrations, different temperatures, sealed or exposed to the air, or left in pure water. Over a period of days, observations can be made on the condition of the peas.

• Ask students to draw parallels between the 1918 influenza pandemic and the threats posed by more recent outbreaks. There are good historical resources at: http://news.bbc.co.uk/1/hi/health/3455873.stm

www.archives.gov/exhibits/influenza-epidemic

• The Virtual Museum of Bacteria contains links to some useful exercises on epidemiology and pandemics:

http://bacteriamuseum.org/cms/Pathogenic-Bacteria/pathogenic-bacteria.html

John Snow’s location of the source of cholera in London in 1854 is a good example of the detection of infection in water.

• Students can research new uses of bacteria in bioremediation and assess the likelihood of success of these projects as well as potential dangers.

• For general information on the teaching of microbiology, the following sites have useful links and resources:

http://www.microbiologyonline.org.uk/

www.microbes.info/resources/Education_and_Learning

Links to TOK

• Correlation and causation can be discussed in relation to transmission of food poisoning. Causation is difficult to identify in many cases but is very important to public health (for example, see the John Snow example mentioned above).

• Measurement of risk is difficult in many situations involving disease transmission and control. Recent measures taken to prevent the spread of SARS and swine flu can be discussed. How can sensible precautions be defined?

Links to ICT

• If fieldwork can be carried out, students can use oxygen probes and nitrate measurements to relate biochemical oxygen demand (BOD) to species diversity in waterways.

Aspects of internationalism

• International cooperation is vital in limiting the spread of infection and in carrying out preventative measures such as vaccination programmes. What is the role of international agencies, such as the UN and WHO, in preventing epidemics and pandemics?

• How important to developing countries is the use of biofuels that can be produced on a small scale?

• What are the attitudes of different countries and cultures to the use of new treatments such as gene therapy?