Developing a dichotomous key for local species
Practice Flashcards
Flip to reveal answersDefine a dichotomous key.
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 12 Flashcards — Developing a dichotomous key for local species
Sign up free to track progress and get spaced-repetition review schedules.
Question
Define a dichotomous key.
Answer
An identification tool made of **paired either/or choices** about observable features, each leading to another step or to an organism's **name**.
Question
What does 'dichotomous' mean?
Answer
**Split into two** — every step offers exactly **two** opposite choices.
Question
Where do you always start when using a key?
Answer
At **Step 1** (the top), then follow the matching choices in order.
Question
Define an observable feature.
Answer
A characteristic you can **see or measure** directly — e.g. legs, shell, scales, wings.
Question
What does it mean when an organism 'keys out'?
Answer
The key has reached the point that **names (identifies)** the organism.
Question
How many choices does each step of a dichotomous key give?
Answer
**Two** — a pair of opposite either/or statements.
Question
Why must key choices be opposite and clear?
Answer
So every organism fits **exactly one** side at each step, with **no overlap**.
Question
Why is 'lives in a pond' a poor choice for a key step?
Answer
Habitat is **not a body feature** — a key must use features you can **observe** on the organism.
Question
How should you move through a key at each step?
Answer
Follow **only the choice that matches** your organism, then go to the step or name it points to.
Question
Why is it useful to write down your route through a key (e.g. 1 → 3 → snail)?
Answer
It shows the **correct path** for the marks and helps you **avoid careless slips**.
Question
Should you identify an organism from its name or its features?
Answer
From its **observable features** — follow the key; never guess from the name.
Question
What is a couplet (step) in a key?
Answer
One **numbered pair** of opposite statements; you pick the one that matches the organism.
Read the notes
Full study notes for Developing a dichotomous key for local species
Topic 1.6 hub
Diversity of organisms
More from Topic 1.6
All flashcards in this topic
Biology exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free