Date Due _______________________
Observe Bread Mold- A Heterotroph
Learning Target: Compare and contrast an autotroph and heterotroph. (reasoning)
Organisms that obtain food by consuming other living things are known as heterotrophs. Some
heterotrophs get their food by eating plants such as grasses. Can you think of an example? __________
Other heterotrophs, obtain food from plants indirectly by feeding on plant-eating animals. Can you
think of an example? _________________ Still other heterotrophs obtain food by absorbing nutrients
from decomposing organisms in the environment. Can you think of an example? __________________
Moldy bread sample (prepared by your teacher 1-2 weeks ago)
The colorful growth on the bread is made of connected thread structures called hyphae. These form a
mold colony which was started by a single mold spore. The hyphae may look soft and fuzzy, or it could
be very colorful. By looking at the hyphae under a microscope, you will be able to identify what kind of
mold it is.
Safety Note: When handling mold, it is very important to cover as much skin as you can, and to wear
gloves. Mold is an allergen. Working with mold as you are in the experiment typically only affects the
very young or very old, or those with severe immune problems, but it is important to take precautionary
measures (like wearing a mask) and to not do this project if you have allergies or asthma.
1. Use lens paper to clean your microscope eyepiece, objective lenses, and diaphragm. Also clean
your class slide and cover slip.
2. Using an eye dropper, place a drop of methylene blue in the center of the slide. Methylene blue
is a biological stain, and makes the sample easier to see by coloring certain parts of the mold
cells. However, it will also stain you and your clothes blue so be careful.
3. Using a toothpick, scrape some of the mold off of the bread, and place it in the drop of
4. Take the cover slip and set it at an angle to the slide so
that one edge of it touches the stain drop, then carefully
lower it over the drop so that the cover slip covers the
specimen without trapping air bubbles underneath.
5. Use the corner of a paper towel to blot up any excess stain at the edges of the cover slip.
6. View the slide with a compound microscope, starting with a low objective.
7. View the data table to determine which type of mold you are observing.
8. Create scientific drawings of your observations. Be sure to title your drawing under the circle
(which represent your field of view) and include the total magnification.
Rhizopus Aspergillus Penicillium
feeds on starch or sugar, found on food items, can be blue-green or gray,
commonly found on bread especially grains often with a fuzzy white
may start off as white hair- typically a bluish green color, edge
like structures and with a thin ring of white under a microscope, you will
eventually will form solid around each colony see that the head has
black spots under the microscope, has a thinner structure than
under the microscope, thin branch-like structure, Aspergillus, with several
appears as short strands with heads that look like strand segments branching
with oval-shaped heads, blooming flowers out from the main strand
looking like a balloon on a at the end of each segment
string of the head you should be
able to see small spores
1. Put the bread and anything that touched it in the zip-lock bag, and throw it away.
2. Wash and dry the slide and cover slip.
3. Clean the area you were working in thoroughly with soap and water and wash your hands.
1. Define heterotroph. __________________________________________________________________
2. Why is bread mold an example of a heterotroph? __________________________________________
3. What value do you see in an organism such as mold? _______________________________________
4. Why are some molds a problem for humans? _____________________________________________
5. Name all the Kingdoms that include example of heterotrophs. ________________________________