Robert Gardner - Genetics and Evolution Science Fair Projects, Revised and Expanded Using the Scientific Method

Your Genes Hold the Key to Who You Are....

Why do some humans have curved thumbs, while others have straight thumbs? What is DNA? What happens during cell division? Using easy-to-find materials, young scientists will explore genetics, evolution, classification, and moreall with the help of the scientific method. For students interested in competing in science fairs, the book contains lots of great suggestions and ideas for further experiments.

ABOUT THE AUTHOR

Robert Gardner is an award-winning author of science books for young people. A retired high school teacher of physics, chemistry, and physical science, he enjoys writing, biking, and doing volunteer work.

This book would not have become a reality without the loving support of my wife, Joan. Thanks to my partners at Neo/SCIKurt Gelke, Jean Coniber, and George Nassiswhose support is greatly appreciated. Special thanks to Ken Rando, who, as always, helped with the electrons.

Charles Darwin explained how genetic variations created a variety of life on Earth. This statue at the Natural History Museum in London honors his life and work.

The science projects and experiments in this book explore the many similarities and differences among living things. Similarities and differences are used to classify plants and animals into groups that share certain characteristics. The task of classifying organisms was first done by Carl von Linn (Carolus Linnaeus) during the eighteenth century. A century later, Charles Darwin developed the theory of evolution. It explained the vast variety of life and provided an explanation for the appearance of new species and the extinction of others.

Darwin based his theory on the variations that exist in living organisms. He was never able to explain the cause of variations found within a complex species, such as humans. That aspect of evolution was made clear by the laws of genetics, first formulated by Gregor Mendel later in the nineteenth century.

As you read this book, your experiments will show how the genes transferred during reproduction give rise to the variations that allow species to evolve. Genes make up the chromosomes found in living cells. Today, we know the chemistry of genes. They are found in DNA (deoxyribonucleic acid), a long molecule shaped much like a spiral staircase.

This book contains lots of fun experiments about genetics. Youll also be given suggestions for independent investigations that you can do yourself. Many of the experiments are followed by a section called Science Project Ideas. This section contains great ideas for your own science fair projects.

To do some of the projects in this book, you may need people to help you, because more than one pair of hands may be required. Try to choose helpers who are patient and who enjoy experimenting as much as you do.

The experiments are all easy to do and safe to carry out when the instructions are followed as given. Consult with your school science teacher or some other responsible adult to obtain approval before starting any experiments of your own.

If any danger is involved in doing an experiment, it will be made known to you. In some cases, to avoid any danger to you, youll be asked to work with an adult. Please do so. We dont want you to take any chances that could lead to an injury.

Most of the materials youll need to carry out the projects and experiments described in this book can be found in your home. Several of the experiments may require items that you can buy from a supermarket, a hobby or toy shop, a hardware store, or one of the science supply companies listed in the appendix. As you begin to use this book, show it to one of the science teachers in your school. Perhaps the teacher will allow you and some of your friends to use the schools equipment.

As you do these projects, you will find it useful to record your ideas, notes, data, and anything you can conclude from your experiments in a notebook. That way you can keep track of the information you gather and the conclusions you reach. It will also allow you to refer to other experiments youve done that may be useful to you in later projects.

When scientists have a question to answer, they start by researching. They read scientific literature and consult online science databases that are maintained by universities, research centers, or the government. There, they can study abstractssummaries of reportsby scientists who have conducted experiments or done similar research in the field.

In this way, they find out whether other scientists have examined the same question or have tried to answer it by doing an experiment. Careful research will tell what kind of experiments, if any, have been done to try to answer the question.

Scientists dont want to repeat experiments that have known and accepted outcomes. Also, they want to avoid repeating any mistakes others may have made while doing similar experiments. If no one else has done scientific work that answers the question, scientists then do further research on how best to do the experiment.

While researching for the experiment, the scientist tries to guessor predictthe possible results. This prediction is called a hypothesis.

The scientist hopes that a well-researched and carefully planned experiment will prove the hypothesis to be true. At times, however, the results of even the best-planned experiment can be far different from what the scientist expected. Yet even if the results indicate the hypothesis was not true, this does not mean the experiment was a failure. In fact, unexpected results can provide valuable information that leads to a different answer or to another, even better, experiment.

A scientific experiment starts when someone wonders what would happen if certain conditions were set up and tested by following a specific process. In other cases, scientists must observe conditions that already exist. For example, in an experiment testing how genetic traits are passed to offspring, we can ask the question: How is blue eye color distributed in one family? To find the answer, some possible guesses (hypotheses) would be:

• Blue eye color is a dominant trait passed from one parent.
• Blue eye color is a recessive trait passed from both parents.
• Blue eye color is coincidental. It is not a genetic trait.

When scientists want to observe genetic traits in humans, they look at what they already know. They record the eye color of as many family members as they can. They chart the eye color to show the eye color of parents and their children. They try to get data on as many generations as possible. Scientists will also compare the data to other families. They will need a large sample of data to show what traits are dominant and recessive.

Careful observation will show that parents with brown eyes may have children with blue eyes. It will also show that in some cases, parents with blue and brown eyes may have children with brown eyes only. This is because brown eye color is a dominant trait and blue eye color is recessive.

Scientists may develop logical explanations for the results of their experiments. These explanations, or theories, then must be tested by more experiments. If the resulting data from more experiments provide compelling support for a theory, then that theory could be accepted by the world of science. But scientists are careful about accepting new theories. If the resulting data contradict a theory, then the theory must be discarded, altered, or retested. That is the scientific method.