Honors Biology Laboratory Report: Yeast Laboratory Report Essay

Yeast Population Growth Laboratory Report Research Question: How do different treatments affect the fermentation and growth of yeast? Purpose: The purpose of conducting the two laboratory activities was to determine how yeast reacts to certain treatments. The effects of two simple sugars were tested, glucose and lactose, in relation to how the yeast ferment. Colony growth was also tested in relation to how yeast grows when plates are streaked with three different substances, glucose, lactose, and nitrate, as well as how colony growth was affected when light intensity was increased.Background: Yeast, a microscopic, unicellular organism belonging to the group of organisms called fungi. Yeast are oceanographers, meaning they do not need the sun to directly acquire energy, and rather acquire it by breaking down the chemical bonds in organic sugars. Yeasts obtain food from fructose, glucose, and other simple sugars, which are found in most fruits. Yeast enzymes chemically break down the sugars into products that the cell can use. Through this process of fermentation, yeast produces carbon dioxide.

In order for yeast to ferment, there must be as little oxygen as Seibel, and an organic compound present.Yeast cannot break down more complex sugars such as lactose, because of the chemical bonds connecting the oxygen, calaboose, and glucose. Glucose is a simple sugar, or macroeconomics, found in many plants. It is one of the main components in photosynthesis, and is needed for cell respiration. Lactose is a disaccharide sugar, or complex sugar, derived from calaboose and glucose that is found in milk. Variables: Activity 1: – Glucose: If we add glucose to the yeast solution, then the yeast would react with fermentation in the form of bubbles.Lactose: If lactose is added to the yeast solution, then the yeast will not react, because it cannot break down the complex sugar.

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Activity 2: – Glucose: Glucose added to the medium will make the yeast population grow more than the other treatments. – Lactose: Lactose added to the agar will make the yeast population grow less than the other treatments. – Light Intensity: Increasing the light intensity around the sample dishes will positively affect the yeast. – Light Intensity: If the Petri dishes are covered in tin foil, then the yeast growth will increase. Nitrate: If titrate is added to the agar medium, then the population of the yeast will provide the same result as the control. Procedure: In this experiment, the effects of glucose and lactose were tested in relation to fermentation rates.

Each group was assigned a sugar solution to combine with their yeast solution. To begin, yeast solution was added to test tubes along with either glucose or lactose. The test tubes were then submerged in hot water. Over a period of time, the bubble height was recorded, and observations were made. Activity 2: In this experiment four different variables were tested in relation to colony and population growth.

Rapid Growth- If, hypothetically, an environment could support unlimited food sources and no predators or diseases, the population could theoretically continue exponential growth. But unless the environment itself can continue growing, introspecting competition would limit the population’s niche expansion. 2. There could have been many human errors which could have created the results reached, rather than the desired results. Because this was the first time an experiment to this caliber was conducted by the scientists, there were many known variables which could have been controlled in a more informed setting.


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