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KABT Labs from the old website

Rebuilding this web site along with adding new content for Kansas biology teachers is an ongoing process. I’ve just added the labs that were posted onto the former KABT web site onto this site under the KABT Resource link in the right hand column. Check them out. I’m posting links to pdf files of the complete labs. KABT members: If you have a lab that you’ve written in some sort of word processing format that you’d like to post here. Let me know and we’ll see if we can get it online.

BW

FRUIT FLY OBSERVATION PROJECT

FRUIT FLY OBSERVATION PROJECT

By Sandy Collins

BACKGROUND

Some time ago I was describing to a colleague, Brad Williamson, a project that I did with my freshmen biology students. It was a laboratory investigation in which the students proposed and tested original hypotheses. Brad’s succinct comment was essentially, fine, but hadn’t I had asked my students to propose hypotheses without allowing them sufficient time to make the initial observations necessary to ask interesting questions. Could he be right again?! Subsequently it also became clear to me that in failing to provide my students with sufficient time to make careful observations, I had denied them the opportunity to begin developing a skill that enhances many experiences – not just those in the science classroom. In an effort to enhance my students’ skills in making detailed observations, I now start the year with a Fruit Fly Observation Project. I describe the project in this paper.

My project is a modification of an activity written by M. Nissani, entitled “Dancing Flies”. The article appeared in the March 1996, issue of The American Biology Teacher. In the original activity, students work through a series of projects in which they observe the behavior of fruit flies and propose and test hypotheses based on their observations. The author summarizes the project as follows: “It fleshes out abstract lectures about life cycles, insect morphology, patterns and causes of animal behavior, and, above all, the nature of science.” My objective in this abbreviated version of the original activity is to offer my students the opportunity to improve their observational skills over an extended period of time by observing a culture of Drosophilia melanogaster.

You’ll find the rest of the lab in pdf format for download here: FRUIT FLY OBSERVATION PROJECT

Exploring Seed Germination

Exploring Seed Germination

by Brad Williamson

Background:

Seeds are very remarkable. Laying dormant inside the seed is an embryo plant. Packed with the embryo is enough stored chemical energy to power the young seedling until it can capture its own energy from the sun by the process of photosynthesis. The timing of germination or the breaking of the dormancy is important to the success of the young seedling. For instance, milkweed seeds that are produced in late summer and fall are carried on the wind, away from the parent plant. They fall to earth in all sorts of environments. If the seed goes ahead and germinates immediately, the young milkweed plant will not be able to produce flowers and seeds before the onset of frosts and winter (at least in the northern U.S.) Milkweed seeds actually don’t germinate until they have experienced long periods of low temperatures. In the spring when the soil is moist and the soil temperature is warm enough a new generation of milkweed to begin. The seed has to somehow respond to signals in its environment in order to germinate at appropriate times.

Many environmental factors can affect seed germination. Light intensity, day length, night length, light color, water, water quality, gravity, crowding, temperature, nearby plants (by chemical agents), genetics, oxygen availability, seed condition, seed age, seed coat condition, seed size and other environmental conditions can have measurable effects on seed germination. Gardeners, worldwide, have a number of ideas of other environmental factors that may influence germination such as the phases of the moon, tidal effects, and planting with companion seeds. Seed germination is a good topic for scientific exploration since it is easy to observe and there are so many obvious and not so obvious environmental factors that can affect the germination.

In order to germinate and break dormancy a seed has to absorb quite a bit of water. In nature seeds absorb this water from the soil. Planting seeds in pots of soil is certainly one way to study their germination and a lot can be learned with controlled experiments. However, observation of soil germinated seeds is not easy-one can only observe the top half of the newly emerged plant. The newly developing roots are equally important when studying seed germination. The method described here involves germinating seeds on a moist filter paper that has a constant source of water. By germinating seeds on a moist paper the root growth can be observed and measured more easily. Also, large numbers of seeds can be tested in a small amount of space in a short period of time.

You’ll find the rest of the lab in pdf format here: Exploring Seed Germination

Seeds

Seed Germination Chamber
Seed Germination Chamber

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A Simple Method to Explore Enzyme Activity

A Simple Method to Explore Enzyme Activity

by Brad Williamson

Enzymes are essential in nearly all life processes. By catalyzing (speeding up a chemical reaction) various chemical reactions in the cell enzymes make energy and nutrients available to living systems. Each enzyme only catalyzes one kind of chemical reaction so there is a lot of enzymes in a typical cell. As the human genome project uncovers the genes in the human population it is important to realize that many of the genes code for enzymes. A basic understanding of enzyme properties then is an essential, first step, to understanding living systems.

Enzyme studies are easily studied by students. For this investigation we will work with an enzyme that begins the breakdown of starch into sugar. It’s called amylase (enzyme) since it breaks down starch (the substrate) which is known as amylose. Scientists use the term substrate to describe the chemical that an enzyme catalyzes. Starch is an energy-storing compound present in many plant foods such as potatoes, corn and bread. Amylase is a component of saliva where it starts the digestion of starch as you chew your food. It’s also a valuable commercial enzyme. The starch in grains such as sorghum are digested with amylase in large reaction vessels to break the starch down to sugar which is then used to produce a number of products. Quite a bit of research that is done by various agricultural product companies attempts to find more efficient forms of enzymes such as amylase. Any organism that might consume starch (including plants) probably relies on some form of this enzyme. And each organism might have just a slightly different form of the enzyme that might be more efficient than others. You might find such an organism and find a valuable enzyme product.

Most of the time biochemists (scientists that study enzymes) work with enzymes in a liquid environment. Such techniques require careful control of a number of variables. A simpler method to study enzymes involves a gel-like substance known as agar. The substrate (starch in this case) is dissolved in this gel and various suspected enzyme-containing substances are added to small holes (wells) in the gel. The suspected enzyme diffuses out through the gel. If it can actively digest starch it will create a starchless area around the well. Iodine stain can be used to cause starch to turn a dark purple. Clear zones that are not purple are areas that the enzyme has digested the starch to sugar. This technique makes it simple to test many samples for activity or to determine the amount of activity a specific enzyme might have. In addition, it is easily modified to test various variables that might affect enzyme activity.

You’ll find the entire lab in pdf format for downloading here: A Simple Method to Explore Enzyme Activity