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IB Biology HL A3.1.14 Hl Dichotomous Key Development Questions

Dichotomous keys identify organisms through paired yes/no choices. Build keys from observable features arranged in a character matrix, and use local plant or animal species to test them.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Identify organisms by following the paired yes/no choices in a dichotomous key.
  • Construct a dichotomous key from observable features arranged in a character matrix.
  • Build and test a dichotomous key using local plant or animal species.

IB Biology HL A3.1.14 Hl Dichotomous Key Development Questions question 1

[Maximum number: 1]

The following shows a dichotomous key.

Four bird heads labelled W, X, Y and Z. W has a deep stout beak with a straight lower edge; X a stout beak with a bend along the upper beak's lower edge; Y a long narrow beak; Z a short curved stout beak.
Dichotomous bird key: long slender beak leads to Certhidea; stout heavy beak proceeds to 2. A flat straight lower-beak underside leads to Geospiza; a curved underside proceeds to 3. A distinct bend along the upper beak's lower edge leads to Camarthynchus; a mostly flat edge leads to Platyspiza.

Using the dichotomous key above, identify the genus of bird W and bird Z .
Bird W:
Bird Z:

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