IB Biology - teaching & learning resources

Option F: Microbes and biotechnology (15/22 hours)

SL students study the core of these options and HL students study the whole option (the core and the extension material).

Core material: F1–F4 are core material for SL and HL (15 hours).
Extension material: F5–F6 are extension material for HL only (7 hours).

F1 Diversity of microbes (5 hours)

Assessment statement

Obj

Teacher’s notes

F.1.1

Outline the classification of living organisms into three domains.

2

Include the use of ribosomal RNA sequences in the classification of the three domains.

F.1.2

Explain the reasons for the reclassification of living organisms into three domains.

3

Powerpoint introduction & Past paper Questions

F.1.3

Distinguish between the characteristics of the three domains.

2

Include histones, introns, size of ribosomes, structure of cell walls and cell membranes.

 

F.1.4

Outline the wide diversity of habitat in the Archae, as exemplified by methanogens, thermophiles and halophiles.

2

Powerpoint of key Archae habitats & question.

F.1.5

Outline the diversity of Eubacteria, including shape and cell wall structure.

2

Powerpoint intro to Eubacteria Shape & walls

Assignment - Questions - or - Pictionary Game

F.1.6

State, with one example, that some bacteria form aggregates that show characteristics not seen in individual bacteria.

1

Biofilm Worksheet

Experiment to extract fluorescent bacteria from dead squid

F.1.7

Compare the structure of the cell walls of Gram-positive and Gram-negative Eubacteria.

3

Details of Gram staining of bacteria are not required.

F.1.8

Outline the diversity of structure in viruses including: naked capsid versus enveloped capsid; DNA versus RNA; and single stranded versus double stranded DNA or RNA.

2

Make notes from the text book.

Examples are not required.

F.1.9

Outline the diversity of microscopic eukaryotes, as illustrated by Saccharomyces, Amoeba, Plasmodium, Paramecium, Euglena and Chlorella.

2

Fish tank & pond water analysis Experiment

Eukarotes Worksheet

 

F2 Microbes and the environment (4 hours)

Assessment statement

Obj

Teacher’s notes

F.2.1

List the roles of microbes in ecosystems, including producers, nitrogen fixers and decomposers.

1

F.2.2

Draw and label a diagram of the nitrogen cycle.

1

Nitrogen Cycle worksheet

F.2.3

State the roles of Rhizobium, Azotobacter, Nitrosomonas, Nitrobacter and Pseudomonas denitrificans in the nitrogen cycle.

1

Experiment to extract & isolate bacteria in root nodules.

nirtogen cycle in a fish tank

F.2.4

Outline the conditions that favour denitrification and nitrification.

2

F.2.5

Explain the consequences of releasing raw sewage and nitrate fertilizer into rivers.

3

sewage sheet

F.2.6

Outline the role of saprotrophic bacteria in the treatment of sewage using trickling filter beds and reed bed systems.

2

F.2.7

State that biomass can be used as raw material for the production of fuels such as methane and ethanol.

1

F.2.8

Explain the principles involved in the generation of methane from biomass, including the conditions needed, organisms involved and the basic chemical reactions that occur.

3

A variety of types of organic matter, including manure from farm animals and cellulose, can be used as the feedstock. Several groups of bacteria are needed to complete methanogenesis.

  • Bacteria to convert the organic matter into organic acids and alcohol.

  • Other bacteria to convert these organic acids and alcohol into acetate, carbon dioxide and hydrogen.

  • Finally, methanogenic bacteria to create the methane, either through the reaction of carbon dioxide and hydrogen or through the breakdown of acetate.

 

F3 Microbes and biotechnology (3 hours)

Assessment statement

Obj

Teacher’s notes

F.3.1

State that reverse transcriptase catalyses the production of DNA from RNA.

1

Complete worksheets using hinemann text book SL.

 

F.3.2

Explain how reverse transcriptase is used in molecular biology.

3

This is an opportunity to relate some aspects of the DNA viral life cycle to that of the HIV virus (an RNA virus). This enzyme can make DNA from mature mRNA (for example, human insulin), which can then be spliced into host DNA (for example, E. coli), without the introns.

F.3.3

Distinguish between somatic and germ line therapy.

2

Somatic cells are diploid body cells,

Germ line cells are eggs and sperm.

F.3.4

Outline the use of viral vectors in gene therapy.

2

This involves the replacement of defective genes. One method involves the removal of white blood cells or bone marrow cells and, by means of a vector, the introduction and insertion of the normal gene into the chromosome. The cells are replaced in the patient so that the normal gene can be expressed. An example is the use in SCID—a condition of immune deficiency, where the replaced gene allows for the production of the enzyme ADA (adenosine deaminase).

F.3.5

Discuss the risks of gene therapy.

3

TOK: There have been some recent cases in countries around the world where subjects have died. These cases could be examined to consider such issues as safety, conflicts of interest and other violations of ethical practice in research.

 

F4 Microbes and food production (3 hours)

Assessment statement

Obj

Teacher’s notes

F.4.1

Explain the use of Saccharomyces in the production of beer, wine and bread.

3

A few words about Louis Pasteur

Traditional Diag of the process of beer making

Notes on the process of making beer.

Microbe Combat Game

F.4.2

Outline the production of soy sauce using Aspergillus oryzae.

2

Simple Outline....

F.4.3

Explain the use of acids and high salt or sugar concentrations in food preservation.

3

Microbes in Food spoilage Experiment

Use of local and/or international examples is recommended.

Notebook on Food preservation -

F.4.4

Outline the symptoms, method of transmission and treatment of one named example of food poisoning.

2

TOK: A correlation may form a useful starting point in an investigation, but, ultimately, clear causal links must be established if public health is to be properly protected.

Salmonella Food poisoning

Key terms and a Quiz on microbes & food

 

HL F5 Metabolism of microbes (2 hours)

Assessment statement

Obj

Teacher’s notes

F.5.1

Define the terms photoautotroph, photoheterotroph, chemoautotroph and chemoheterotroph.

1

Word Document, card sort and definitions sheet, with example organisms

PDF file of notes

 

F.5.2

State one example of a photoautotroph, photoheterotroph, chemoautotroph and chemoheterotroph.

1

see resources above

F.5.3

Compare photoautotrophs with photoheterotrophs in terms of energy sources and carbon sources.

3

F.5.4

Compare chemoautotrophs with chemoheterotrophs in terms of energy sources and carbon sources.

3

F.5.5

Draw and label a diagram of a filamentous cyanobacterium.

1

Use Anabaena and label the photosynthetic cell and the heterocyst.

F.5.6

Explain the use of bacteria in the bioremediation of soil and water.

3

Examples include pesticides in soil, and oil spills on water.

 

HL F6 Microbes and disease (5 hours)

Assessment statement

Obj

Teacher’s notes

F.6.1

List six methods by which pathogens are transmitted and gain entry to the body.

1

F.6.2

Distinguish between intracellular and extracellular bacterial infection using Chlamydia and Streptococcus as examples.

2

F.6.3

Distinguish between endotoxins and exotoxins.

2

Endotoxins: lipopolysaccharides in the walls of Gram-negative bacteria that cause fever and aches.

Exotoxins: specific proteins secreted by bacteria that cause symptoms such as muscle spasms (tetanus) and diarrhoea.

F.6.4

Evaluate methods of controlling microbial growth by irradiation, pasteurization, antiseptics and disinfectants.

3

Evaluating UV light to kill bacteria experiment.

F.6.5

Outline the mechanism of the action of antibiotics, including inhibition of synthesis of cell walls, proteins and nucleic acids.

2

F.6.6

Outline the lytic life cycle of the influenza virus.

2

F.6.7

Define epidemiology.

1

Epidemiology is the study of the occurrence, distribution and control of diseases.

Int: Pathogens do not recognize national boundaries,

F.6.8

Discuss the origin and epidemiology of one example of a pandemic.

3

A pandemic is a very widespread epidemic that affects a large geographic area, such as a continent.

F.6.9

Describe the cause, transmission and effects of malaria, as an example of disease caused by a protozoan.

2

See the notebook files

F.6.10

Discuss the prion hypothesis for the cause of spongiform encephalopathies.

3

TOK: The transmission of spongiform encephalopathies did not fit any of the conventional theories for transmission of infectious disease..

It is now clear that advice given by the scientific community and national governments was misleading over several years.

 

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