Describe one example of a genetically engineered product that has benefited human health. There are three different forms of symbiosis. Describe the possible role of each organism in the wastewater treatment plant, and how their combined activities may eliminate ammonia from the wastewater. Both strains belong to the domain Bacteria , and not to the Eukarya . Name two cellular features that could confirm this.
Milk is pasteurised before sale, but still contains a small number of harmless bacteria.
Explain this observation in terms of the way bacteria grow. Lactose is the main fermentable sugar in milk and, unshaken, mild rapidly becomes anaerobic. How do these two facts explain the bad smell and taste which develops with time. Counts of bacterial numbers in mild are usually done by direct microscopy using special slides marked with grid squares. Outline the advantages and disadvantages of this method compared to carrying out a viable count.