Biology Lessons Part 2: Population Biology

 

 Lesson 2.4: How Do Organisms Vary?

Knowledge Mapping Exercise

Grade Level

Prospective and Practicing K-8 Teachers; may be adapted for use in elementary classes.

Time 

Approximately 1-2 hours.

 Objectives

Once you have completed these exercises you should be able to:
   1. Demonstrate a clear understanding of Mendelian and quantitative traits.
  2. Distinguish between traits and alleles.
  3. Distinguish between alleles and genes.
  4. Refine your skills in categorizing and linking ideas.
  5. Be able to modify an existing semantic network.
  6. Learn how to "get around" a constraint in SemNet.

 Exercise 1

Modify a Semantic Network about Mendelian Genetics

  1.

Begin with the net called "2.4d Mendelian Exercise Net." Your task is to modify this net as described below.

You can download the "2.4d Mendelian Exercise Net" here.

  2. The "2.4c Mendelian Exercise Net" contains the twenty-six concepts shown in Table 1.

Table 1. Twenty-six concepts in the net, "2.4c Mendelian Exercise Net".
allele homozygous dominant genotype quantitative gene
chromosome homozygous recessive genotype quantitative trait
deoxyribonucleic acid Gregor Mendel recessive alleles
description of organism Mendelian allele some alleles in organism
DNA Mendelian gene some traits of organism
dominant alleles Mendelian trait trait
double helix multiple genes specify a trait  
gene one gene specifies one trait  
genotype phenotype  
heterozygous genotype quantitative alleles  

  3. Table 2 summarizes the hierarchical structure of the network. Familiarize yourself with this so you know what categories are available and how they are related to one another. You can also Traverse the net on the Move menu (click on Ask About Each One in the lower left corner of the Traverse dialog box for controls).

Table 2. Hierarchy of Ideas in the "2.4c Mendelian Exercise Net."
 description of organism
has type genotype
has type homozygous dominant genotype
has type heterozygous genotype
has type homozygous recessive genotype
specifies one or more gene
has type Mendelian gene
produces Mendelian trait
has variations called Mendelian alleles
has variations called dominant alleles
has variations called recessive alleles
has variations called co-dominant alleles
has characteristic one gene specifies one trait
contrasts with quantitative gene
has characteristic multiple genes specify a trait
has variations called quantitative alleles
has type quantitative gene
composed of DNA
same as deoxyribonucleic acid
has characteristic double helix
has variations called allele
has variations called dominant alleles
has variations called recessive alleles
has variations called co-dominant alleles
has type quantitative alleles
has type Mendelian alleles
describes some alleles in organism
contrasts with phenotype
specifies one or more trait
has type Mendelian trait
has type quantitative trait
describes some traits of organism
specifies one or more allele
has type phenotype

  4.

Developing skills in using hierarchies and categories is a key to learning biology or any other complex domain of knowledge. Your task in this lesson is to add the concepts in Table 3 to the net at the most appropriate point for each one.

The concepts that are already integrated into the net are in lower case. The concepts to be added are also included in your document but are not yet attached to the knowledge network. They are in upper case so you can distinguish the new from the old. As you add them to the net, let the name completion function help you.

Table 3. Words to Connect to the Knowledge Network in the" 2.4c Mendelian Exercise Net." Incorporate these ideas into the knowledge net.
BB GENOTYPE EE GENOTYPE RECESSIVE TRAIT
Bb GENOTYPE Ee GENOTYPE TONGUE CURLING
bb GENOTYPE ee GENOTYPE TT GENOTYPE
BENT LITTLE FINGER HEIGHT Tt GENOTYPE
BLOND HAIR INTELLIGENCE tt GENOTYPE
BLUE EYES LL GENOTYPE WEIGHT
BROWN/BLACK HAIR Ll GENOTYPE WIDOW'S PEAK
CC GENOTYPE ll GENOTYPE WW GENOTYPE
Cc GENOTYPE MID-DIGITAL HAIR Ww GENOTYPE
cc GENOTYPE MM GENOTYPE ww GENOTYPE
CURLY HAIR Mm GENOTYPE  
DOMINANT TRAIT mm GENOTYPE  
  5.

Begin by adding all the genotypes to their appropriate categories using the existing relation ray, "is an example of". Here you must pay close attention in order to "outsmart" the software. SemNet is not case-sensitive. That is, to SemNet, the concepts BB GENOTYPE, Bb GENOTYPE, and bb GENOTYPE are identical and will be merged together. To override this undesirable outcome, we have put one space within BB GENOTYPE, two spaces within the Bb GENOTYPE, and three spaces within the bb GENOTYPE. That is,

BB GENOTYPE (1 space)
Bb GENOTYPE (2 spaces)
bb GENOTYPE (3 spaces)

Each time you enter a concept or phrase containing extra spaces, SemNet asks if you want to strip (remove) the extra spaces. Usually you click on" OK". When you specifically want the spaces, however, you must click on "keep" not once but twice.

  6. The same pattern of spaces has been followed for all genotypes. Pay close attention to enter the correct number of spaces to represent each genotype.
  7. Next add each of the traits to the net at the most appropriate point, again using the relation ray, "is an example of."
  8. The third step is to join each trait with its related genotypes using the relations, "is caused by / causes" and "is not produced by / does not produce." For example, you could say that BENT LITTLE FINGER is caused by BB GENOTYPE and Bb GENOTYPE. You could also say that BENT LITTLE FINGER is not produced by bb GENOTYPE. Do this for each trait.
  9. If you make an error and need to delete an instance, go to the Instance menu and select Delete.
  10. Review the net and add other items. For example, can you define dominant and recessive allele? Can you define Mendelian and quantitative traits? Can you define gene and allele? Can you classify each trait as to whether it is a dominant trait or recessive trait using the existing "type of / has type" relation.
  11. Two common diseases are caused by single point mutations in Mendelian genes. They are hemophilia (HH, Hh, and hh) and sickle cell anemia (SS, Ss, and ss). The homozygous recessive individuals have the disease and the heterozygotes are carriers. Can you integrate this information into your net?
  12. To review your final net hierarchy, go to the Display menu and select Relations - Creation Order. Flag each relation using the Flag command on the Relation menu (an asterisk will appear next to the relation as it is flagged). Choose the Hierarchy - Outline command from the Display menu. Type in the name of the highest concept in the net (such as descriptions of organisms) and use the default "Flagged relations." Click on OK.
  13. When the hierarchy is displayed, choose Copy Window Contents from the Edit menu. Paste the copy into a word processing program. Save the hierarchy and print it out.
  14. Use your printed hierarchy as a guide to reconstruct your net in the form of a concept map on a large piece of butcher paper, and post it on the wall.