6.08 Fungus Lab: Growing Yeast

How was the hike? Did you get to relax a bit and see lots of fungi? Give me just a second; I'll clean up here and get you some refreshments. However, since you've been looking at fungi, let me tell you about a very special one that I use in baking bread—yeast.

These one-celled organisms are a very important group of fungi. The common yeast used in baking bread grows and reproduces very quickly. So we use them to make our dough rise. The yeasts use the sugar in the dough for their life processes and, as a result, produce carbon dioxide gas (CO₂) as a waste product. The bubbles of gas cause the bread to plump up, or rise, and when we slice it later you can see the holes. They also produce an acid which gives some bread, like sourdough, its strong flavor.

Growing Yeast

Remember to plan! This experiment will take two days to fully complete.

Here's what you are going to do. The basic idea in this lab is to measure the amount of carbon dioxide (CO₂) released during the growth of yeast. The growth of the yeast stops when one of the nutrients required by the yeast is gone (you'll test a few of these energy sources), or when the liquid gets too acidic (low pH) and kills the yeast (this may be a variable too).

1. Open the lab report provided below. Save a copy and print it out.
2. You will need to complete the sections with the " Red headings.

Growing Yeast Lab Report

When you have submitted the completed lab report, you can continue to the Review page.