Hands-on Science Activity - What is Fungus and What Does it Do in Our Environment?

Materials:

Small plastic dishes (disposable picnic type, light in color), plastic wrap, small pieces of cheese, bread, fruit (such as strawberries), warm and dark location, hand lens, drawing materials.

Fungi are plants which are not as advanced as green plant species. As you will recall, green plants are able to make their own food through the process of photosynthesis (using sunlight to combine water and carbon dioxide to produce sugars).

Fungi must feed on other materials to survive. This is beneficial to our environment as these species are able to biodegrade, or break down, certain other materials. There are many different types of fungi in our environment. We are all familiar with fungus in the form of mushrooms and also the dark fuzzy stuff which grows on the food we neglect to eat in a timely fashion! Some fungi are beneficial, others are poisonous (such as deadly mushrooms) and disease causing (such as those involved with infections of body organs, like lungs or kidneys). In this activity we will grow a fungus and have a close look at it.

Other organisms which also contribute to the process of biodegradation are bacteria. They too will be involved in this activity, but they will not be able to be observed due to their microscopic size.

The fungus grown in this activity can be retained for the Use from Refuse activity later at this grade level.

Instructions:

• Working in groups of three or four, place small pieces of foods in dishes, a different type of food in each dish. If using bread, use one without preservatives (organic breads are readily available in bakeries and grocery stores). The bread should be a little moist; if necessary, add a few drops of water.

• Cover each dish with a piece of plastic wrap (this will hold moisture and speed up the biodegrading process). Have students mark their containers in some fashion so that they can be retrieved occasionally for observations.

• A sketch should be made of each of the food types on day one. Place the food samples in the dark, or at least out of the way of direct sunlight.

• Every day or two, the food samples should be observed and changes in the appearance of the food noted, either by sketching or in writing. Depending on environmental conditions, the fungus should grow to the point of being easily observed within 5 days. Please note that warmth, darkness, and moisture are the favorable conditions for the growth of fungus.

• When the fungus (which will be mostly black, grey, and white, and bumpy and fuzzy in appearance) is readily observable with the naked eye, observe it closely with a hand lens and sketch. Compare these sketches with the ones from day one. You will see round, ball-like structures - these are the fruiting bodies which contain spores. When these structures open, spores are released in the air. They settle and more fungus grows if the conditions are right (warm, moist, dark, and ample food to feed upon). The branching structures are the non-reproductive part of the fungus, called rhizoids.

Questions for students:

(1)    Which food grew fungus first?

(2)     Which food had the most fungus?

(3)     Are the fungi on all of the food samples the same or different from each other? Describe.

(4)     How is the food different from the first day of this activity? Carefully scrape away a little of the
          fungus and observe the surface of each food sample. Describe.

(5)     From where do you think the fungus came? How did it get on your food
          samples if the food samples were covered with plastic wrap?

(6)     Now that you have done this activity, how would you explain "biodegradable" to someone?