Back to the list of Challenges ... Next Challenge

Challenge #24

Challenge "Stumper" Question #1

Can you identify this organism?
1. It is a single-celled, living organism whose enduring, wild spores are dispersed through the air. It has been known (and made use of) by humans for millennia.
2. This organism was probably first used by humans in the preparation of a beverage. Later, perhaps about 5,000 years ago, it was used in the preparation of solid food.
3. Its scientific (Latin) name is Saccharomyces which identifies the genus to which it belongs.

(Answers to both Stumper Questions are given together - see below)

Challenge "Stumper" Question #2

Many things that we cannot normally see have beneficial affects in our lives. Take for example, bacteria. The metabolic processes and products of bacteria are important in many ways including the manufacture of vinegar and some cheeses, the curing of black tea, coffee, cocoa and vanilla beans, the tanning of leather, and the production of silage. And, bacterial flora inhabiting the intestines of animals often play a part in digestion.
Certain soil bacteria are important because they help maintain soil fertility which affects crop growth. These include some free living bacteria and some that live in a symbiotic relationship in the roots of certain plants. Their contribution to the enrichment of soil occurs because they help convert a particular gas into a form that is usable by plants. During the process of their normal metabolism they combine the gas with hydrogen to form a simple compound that reacts with substances in the soil to form a different compound. This new compound is used by the plant in the manufacture of complex organic molecules essential to both plant and animal life. The complex organic molecules are amino acids and proteins.

What is this element that is freely abundant as a gas, is an essential component of all living organisms, but is not normally available to plants or animals until after it has been used in the metabolic processes of soil bacteria?


Back to the list of Challenges

Send feedback to
Explorit Science Center
P.O. Box 1288, Davis, CA 95617, USA
Phone: (530)756-0191     Fax: (530)756-1227