Read Through the Introduction of Lesson 2.20

Graded AssignmentSCI202B: Biology | Unit 2 | Lesson 20: Laboratory: Dichotomous Keys

Name: / Date:

Adjusted Graded Assignment

Read through the introduction of Lesson 2.20

On page 3 of the lesson, there is a sample dichotomous key that can be used to identify several types of birds. Click the “Dichotomous Key” link and identify all 5 types of birds by using the key. Fill in the names below.

Name of Bird
A
B
C
D
E
Score
/5 pts

Lab Report

Create a dichotomous key that identifies the 10 leaves on the Common Leaves Sheet. Look closely at those leaf samples and devise a dichotomous key that helps you identify them. Be sure that your dichotomous key contains only pairs of statements about a single characteristic. For example, a pair of statements might be:

A. leaf margin smooth
B. leaf margin toothed

However, you should avoid pairs of statements that do not address the same characteristic. The following pair, for example, would not be very informative in your key:

A. leaf margin smooth
B. leaf type needle-like

As you develop your key, test it out with the 10 leaves provided on the Common Leaves sheet. When you've developed a key that identifies all 10 leaves, type your statements, “go tos,” and identifications, following the format in the example below. The example is based on this lesson’s dichotomous key for birds.

Statement 2a / The bird has a crest of feathers on the top of its head. / go to statement or identify bird / blue jay
Statement 2b / The bird has a smooth head. / go to statement or identify bird / 3

Once you have completed your dichotomous key, answer the two remaining questions. When you are finished, submit this assignment to your teacher by the due date for full credit.

Score
/15 pts

Complete a dichotomous key for the 10 leaves on the Common Leaves sheet. The chart provided here allows for 11 pairs of statements. Depending on how you build your dichotomous key, you may or may not need all of them, or you may need to add some.

Answer:

Statement 1a / go to statement or identify leaf
Statement 1b / go to statement or identify leaf
Statement 2a / go to statement or identify leaf
Statement 2b / go to statement or identify leaf
Statement 3a / go to statement or identify leaf
Statement 3b / go to statement or identify leaf
Statement 4a / go to statement or identify leaf
Statement 4b / go to statement or identify leaf
Statement 5a / go to statement or identify leaf
Statement 5b / go to statement or identify leaf
Statement 6a / go to statement or identify leaf
Statement 6b / go to statement or identify leaf
Statement 7a / go to statement or identify leaf
Statement 7b / go to statement or identify leaf
Statement 8a / go to statement or identify leaf
Statement 8b / go to statement or identify leaf
Statement 9a / go to statement or identify leaf
Statement 9b / go to statement or identify leaf
Statement 10a / go to statement or identify leaf
Statement 10b / go to statement or identify leaf
Statement 11a / go to statement or identify leaf
Statement 11b / go to statement or identify leaf
Score
/2 pts

Can more than one dichotomous key be developed to identify the same group of organisms? Explain. To answer this question, refer to this lesson’s dichotomous key for birds.

Answer:

Score
/2 pts

If two different people use the same dichotomous key to identify the same organism, should they have different results? Explain.

Answer:

Your Score / ___ of 24

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