Chapter 11, Problem 2A

Summary Introduction

To write:

The correct vocabulary term for the given question

Introduction:

Scientists study genetic relationships by performing several experiments with plants and some animals like fruit flies. It is easy to conduct crosses in peas and fruit flies because the results are quick but it is difficult for scientists to study genetic relationships of humans and other mammals. It would take several generations to get desired results.

Answer to Problem 2A

Pedigree

Explanation of Solution

Scientists study family history using a diagram that traces inheritance of a particular trait through several generations. Such diagrams are called pedigree. A pedigree uses symbols to illustrate the inheritance of trait. By analyzing the pedigree we can predict if the person will suffer from disease or will be a carrier of the disease or will be disease free.

The given pedigree illustrates inheritance of a genetic disorder. In this diagram, I1 and I2 are parents who carry the genes for a disease/ disorder. Males are represented by squares and females are represented by circles. One who expresses the trait is represented by a dark, or filled square or circle. In this pedigree, II1 is dark. So it expresses the trait and would develop symptoms of the disease. In a pedigree diagram, an unfilled square or circle does not express the trait. II4 will not express the trait. It does not carry the gene for disorder. A partially filled square or circle does not express the trait but is a carrier of the trait.