Unit 2 – Yeast Respiration Lab

Yeasts are known to be used for making beer and bread, but how do they actually contribute to these products? The answer is simple: anaerobic respiration. Plants and animals need to constantly respire to sustain their lives. This means they need to respire no matter air (oxygen) supplies is available or not. This brings back to anaerobic respiration. Anaerobic respiration is when an organism has to respire without oxygen, and aerobic respiration is when the organism respire with the presence of oxygen.


Given this, it is still unclear how yeast help make bread or beer. How do they actually do this? To answer the question, let’s explore into the process of anaerobic respiration. In anaerobic respiration, organism goes through fermentation, a process to restore the materials needed for the next respiration process. Normally, organisms would not do this, but because of the lack of oxygen, they have to. In animals, they go through lactic acid fermentation. This lactic acid causes the pain that can be experienced when we exercise because through exercise, we do not get enough oxygen. Another type of fermentation is alcoholic fermentation, a process that plants including yeast (fungi) go through.


By going through anaerobic respiration, yeasts use sugar molecule to act upon and produce some energy and carbon dioxide and ethanol as their byproduct. That concludes why yeasts are used for they are used for. In making beer, the ethanol they produce is favored. In making bread, the carbon dioxide they release is favored for creating air bubbles in the dough as well as to raise the dough.


In a lab for AP biology this unit, we conducted a yeast respiration lab to observe and learn the process described above. In this lab, we immersed yeasts in different solution such as, distilled water, water and sugar, honey and water, water and Royal D and water and vanilla extract which are stored their own flask. At the rim of the flask, we attach balloons that would be inflated when yeast respire to see the variation of yeast respiration rate within our different solution. After the experiment is set, we let the flask sit for an hour before we make our observation.

To our surprise, the balloon attached to the flask that holds water and Royal D was inflated the biggest, followed by water and sugar. This means that Royal D holds materials that are favored in yeast respiration; it holds not only sugar but also vitamin and potassium. This may explain why the balloon attached to the Royal D flask was inflated bigger than sugar.  As can be seen in the photo, none of the other ballons were inflated. It is no surprise though that the balloon attached to the water and vanilla extract were not inflated because they do not have sugar which is needed in respiration. Honey, howeve,r came as a little shock, but we hypothesize that the sugar molecule it holds may be too big for the yeasts.

AP Biology-Unit Two | “Cell” Yourself

In the second unit of AP biology, the subject content focuses on the cell. So far, we learned about the different types of cell and the basics of the evolution of eukaryotic cell. Because we will mainly learn, about eukaryotic cells, we did a fun project called “cell yourself” to help us understand cell in an amusing way. In this project, each student in the class was assigned an organelle or part of a cell that they would have to do research on. After the research, we would have to be creative and pretend to be our assigned organelle going for a job interview. This means that we dressed in a costume that represents our assigned item and act like our organelle for the day of our “job interview”.

I was assigned the plasma membrane which act as the bound between the cell and its environment. In addition, it also act as a gate that let material in and out of the cell, a structure for the cytoskeleton to attach to which gives the cell its shape, and communicator for the cell (when they bond with adjacent cell to form tissues).

To represent my part of the cell, I wore camo clothing to depict myself as a protector of the cell  since soldiers (a protector of a country) wear camo clothes. I wear my hand -made earing composed of a bead and two pieces of trailing yarn to represent the phospholipid bilayer that make up the plasma membrane. I wore a cork necklace to represent the carbohydrate present on the plasma and lets bodily cell recognize each other. Lastly, I name myself  Plasmano Elsie Membriano.

During my “job interview” I talked about how vital I am to the “company” (the plant and animal cell), and was at last employed after persuasive speech of “celling” myself.

AP Biology-Unit One | Water Extraction Lab

I decided to sign up for Advanced Placement (AP) biology class because I really love science, and I want my career to be in this path. I want to expose myself to some knowledge that I should know before I enter college, and maybe potentially show my AP biology test score to college to prove my passion for science.

In our first unit of our Ap biology class, we focus on community ecology. As part of the introductory course, we perform a water extraction lab during our first week of class. This lab was basically aimed to calculate the water content of a given fruit or vegetable. My lab partner (Sopor) and I  was assigned an orange. Together, we developed a methodology and extract as much water as possible and calculate its water content; we were off by about 20%. To learn more my lab, please click on the link below and read my lab report.

Orange Water Extraction Lab_Sythong


I was wrapping parts of the orange in a towel to pond the water from the orange into it.
A group photo of the whole class with the remaining from our lab.
A bird’s-eye view of the remaining(s) from the lab(s) performed by students in my AP biology class.