IB Biology Lab Report
Name ______________________________
Date lab was done ____________________
Title:
Construction of a Dichotomous Key
Purpose: To understand the use of binomial nomenclature; to use structural
characteristics of organisms in the construction of a dichotomous
identification key.
Notes:
Construction of a Dichotomous Key
A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such
as trees, wildflowers, mammals, reptiles, rocks, and fish. Keys consist of a series of choices that lead the user
to the correct name of a given item. "Dichotomous" means "divided into two parts". Therefore, dichotomous
keys always give two choices in each step.
In constructing keys, keep the following in mind:
 Use constant characteristics rather than variable ones.
 Use measurements rather than terms like "large" and "small".
 Use characteristics that are generally available to the user of the key rather than seasonal
characteristics or those seen only in the field.
 Make the choice a positive one - something "is" instead of "is not".
 If possible, start both choices of a pair with the same word.
 If possible, start different pairs of choices with different words.
 Precede the descriptive terms with the name of the part to which they apply.
Manipulative skills
Levels/marks
Complete/2
Partial/1
Not at all/0
Aspect 1
Aspect 2
Following instructions*
Carrying out techniques
Follows instructions
accurately, adapting to
new circumstances
(seeking assistance when
required).
Follows instructions but
requires assistance.
Competent and
methodical in the use of a
range of techniques and
equipment.
Pays attention to safety
issues.
Usually competent and
methodical in the use of a
range of techniques and
equipment.
Rarely competent and
methodical in the use of a
range of techniques and
equipment.
Usually pays attention to
safety issues.
Rarely follows instructions
or requires constant
supervision.
Aspect 3
Working safely
Rarely pays attention to
safety issues.
Construction of a Dichotomous Key
Study the physical characteristics of the 10 mythical creatures in the diagram provided. Give each organism
an appropriate name using correct binomial nomenclature format. Design a dichotomous key for the
identification of all 10 species.
Dichotomous Key:
Answers:
Number
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Name