BIO 315 Week 3 Individual Assignment Yeast Culture Lab

BIO 315 Week 3 Individual Assignment Yeast Culture Lab

Yeast, is a microscopic one celled organism that belongs to the group of organisms that is called fungi. They are single celled organisms that have a scientific name of Saccharomyces cerevisiae. Yeast can have many purposes but the main purpose of yeast is to help the fermentation process. Yeast is a living organism known as a fungus and it gets its energy source from sugar. Yeast can also be used in creating certain medical intentions that heal wounds and reduce inflammation because of the large amount of hormones and enzymes.

In reference to yeast reproduction depends on the type of species because they can be either asexual by mitosis or sexual by budding. Consumption talked about the use and rate of use of a primary consumer that needs photosynthesis in order to create energy from CO2. Death is in reference to a population and refers to the toll of death in a population.


This labs main objective is to test cultures referring to yeast. The hypothesis is that the yeast will grow in all the environments that it is placed in but it will thrive in the environment that has sugar that is because yeast uses sugar as an energy sources naturally which will make the yeast generate more. The yeast could be identical in all the environments but most likely the situation will be that the yeast grows rapidly in the sugar.

This hypothesis needs to be tested and in order to do that their needs to be an amount of yeast from different environments collected analyzed and then have the data provided. The data was tested in four different environments and observed for 0,24, 48, 72, and 96 hour intervals. The environmental conditions used were a controlled environment, limited reproduction environment, additional food environment and introduced predation environment.


These materials are needed to complete the experiment:

4 – Yeast packets

1 – Ammonia mixture

1 – Sugar mixture

1 – Distilled water

1 – Balance

1 – Microbe Mixture

1 – Eyedropper

1 – Microscope

4 – 10mL graduated cylinder

4 – 18mm x 150 mm culture tuber

1 – Test tube rack


The steps were taken to conduct the experiment:

First the test tubes need to be labels with all the different materials that will be mixed into the yeast. The four labels will be Control, Ammonia, Sugar and Microbe. The lab data sheet will also have the names of each tube with the time and concentration of each solution so that all the data can be recorded.

Second the tube will be filled with the solution up to 10 ml of the solution.

Third the yeast suspension will be mixed in a separate container and will add drops of this solution to the each tube.

Fourth take out a drop of each solution from a tube and observe it under a microscope. The results will be documented on the data sheet and this step will be repeated in each time interval of 24, 48, 72 and 96 hours.

Fifth the lab needs to be cleaned up and have everything put back and record all the data and look over the results.


Once the experiment was conducted and all the data was recorded the data had to be analyzed. The hypothesis that was predicted was found to be correct. The yeast in the solutions tubes did become active; the yeast tube with the sugar was the tube that became the most active. In all the tubes the yeast physically expanded the tube with the sugar physically expanded to twice the size of the other tubes. This made the solution rise to the edge of the test tube. The yeast and sugar solution grew to more then 200 the count level and the other solution only exceeded the 100-count level. The data graph below shows that the solution had a constant rise and shows the population peaks and declines due to the reproduction rate. The yeast solutions eventually begin to die off.