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Hi dallas99,
I don't think this is hard to do. Here's my approach to extrapolating the answer to 200 hours.
1) take the average for each time interval (add the dots in all three observation and divide by 3)
2) Plot the averages as y and time as x.
3) Draw a smooth curve that connects the dots until you reach 200 hours.
The factors that universally affect all biological populations are:
Biotic factors - such as food, disease, competitors, and predators AND
Abiotic factors such as rainfall, floods, and temperature.
Of these, the ones that make sense are food, competition among the population itself, and temperature.
When it comes to generalizing for yeast only:
Temperature
Yeasts can tolerate extreme temperatures although it may lose its viability with time. Some yeast live in freezing conditions but many will grow in normal environmental temperatures existing in many places. Therefore, refrigeration or deep freezing may not be a full proof method to prevent yeast formation.
Acidity
Many species of yeast grow in media with a neutral PH or slightly acidic PH. Thus, yeast extracts or foods derived from yeasts are more likely to be acidic. When it comes to culture medium, scientists use the same characteristic in organic acids for its use as an effective culture medium.
Sugar concentration
As described earlier, yeasts require organic compounds such as sugar derivatives to obtain energy and therefore its concentration in the culture medium or in the environment will affect the rate of its growth.
Type of strain
Certain strains or species of yeasts will grow rapidly whereas some may be relatively slow. However, further research is required to link type of strain and its growth to understand its correlation better.
Oxygen
As described earlier, although anaerobic respiration is possible, many yeast strains will require oxygen enriched medium for its metabolic functions. Thus, when yeasts grow in a lab, they receive an aerobic environment for effective growth.
Minerals
Minerals such as magnesium, potassium and several other trace elements are essential for yeast growth and therefore should encourage growth when provided externally.
Phosphorus
When considering its part as an element in the nucleic acids and phospholipids, provision of phosphorus is important for effective yeast growth.
Sulphur
It is an essential element of certain amino acids and when added to a culture medium, it will encourage yeast growth.
Growth factors
Scientists have learn that, yeasts require certain vitamins, purines, pyrimidines, amino acids, fatty acids…etc for catalyzing the biosynthesis although they do not act as energy sources for yeasts. Therefore, such factors are named as ‘growth factors’ and should be available in trace quantities in the culture medium for optimal growth.
Apart from the above, there can be many other factors contributing to the growth of yeast and require further research to determine how extensively they affect in their growth..
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