Naming with a key — questions

1. identify

Use the six-tree key. A leaf is one blade, has no spines on the edge, and its lobes run along both sides of the midrib. Which tree is it?

Circle one answer.

• Oak
• Sycamore
• Holly
• Field maple

Nudge (only if you are stuck): Start at pair 1 and read both statements each time before you choose.

2. sequence

Put the steps for building a dichotomous key in order.

Write the number of each step in order.

1. Write the feature as a pair of opposite statements
2. Run each organism through the key to check it reaches its own name
3. List features that some of the organisms have and others do not
4. Do the same for each smaller group until each organism is on its own
5. Choose a feature that splits the whole group into two

• First: ______
• Second: ______
• Third: ______
• Fourth: ______
• Last: ______

Nudge (only if you are stuck): You cannot write statements until you know the features. The final test runs every organism through the finished key.

3. identify

A pupil is making a key for an earthworm, a snail, a spider and a beetle. Which question is the best first step?

Circle one answer.

• Is it big or small?
• Does it have legs, or no legs?
• Is it a spider?
• Is it brown?

Nudge (only if you are stuck): A good step uses a feature that every animal clearly has or has not, and splits the group.

4. identify

Use the key to garden animals. An animal has fourteen legs and a body covered in grey plates. Which pairs of the key does it pass through, and what is it?

Circle one answer.

• 1 → 4: snail
• 1 → 2: ant
• 1 → 2 → 3: woodlouse
• 1 → 2 → 3: centipede

Nudge (only if you are stuck): Count the legs: is that six, or more than six?

5. identify

Which of these are identifiable features that could be used in a key for summer leaves of the six trees in the reading? Choose all that apply.

Tick every correct statement.

• The leaf is divided into leaflets
• The leaf is large
• There are spines on the edge
• The leaf is pretty
• The leaf has lobes
• The leaf is green

Nudge (only if you are stuck): An identifiable feature can be seen, counted or measured, and two people looking at the same leaf would describe it the same way.

6. explain

A pupil makes a key for six kinds of leaf collected in summer. All six leaves are green. The first pair is "Leaf is green / Leaf is not green". Explain why this is a poor first pair, and suggest a better one.

Nudge (only if you are stuck): All six leaves are green. What happens to the group at this pair?

7. construct

Construct a dichotomous key for these four animals: a frog (smooth, moist skin and four legs), a lizard (dry, scaly skin and four legs), a snake (dry, scaly skin and no legs) and a goldfish (scales, fins and no legs). Write each pair as two opposite statements.

Pair 1

Pair 2

Pair 3

Nudge (only if you are stuck): Which feature splits the four animals two and two? Then find one feature to split each pair.

8. calculate

A dichotomous key is made for 12 species of beetle. How many pairs of statements does it need?

Number of pairs of statements: ______________ unit ________

Nudge (only if you are stuck): Each pair splits one group into two. Start with one group of 12: how many splits until there are 12 groups of one?

9. evaluate / construct

Here is a key a pupil wrote for four garden birds. Male blackbird: all black feathers and a yellow beak, about 25 cm long. Magpie: black and white feathers and a long tail, about 45 cm. Robin: brown back and an orange-red breast, about 14 cm. Blue tit: blue cap, yellow breast and green back, about 12 cm. (a) Find two faults in the key. (b) Rewrite the faulty statements, using the features given, so that the key works.

(a) Two faults

(b) Rewritten statements

Nudge (only if you are stuck): Check each statement: could two people disagree about it? Does any statement give the name away?

10. explain

A visitor to a botanic garden uses the six-tree key. (a) The first leaf is one blade with no spines, and its lobes spread from one point and have smooth edges. The key gives "field maple", but the label on the tree shows a different species of maple, which is not in the key. Explain how the key could give a wrong name although every choice was right. (b) The second leaf is one blade with no spines and no lobes at all. At pair 4 neither statement fits. What should the visitor do, and why? (c) What do (a) and (b) tell you about using a key?

(a) How the key gave a wrong name

(b) Neither statement fits: what to do

(c) What this tells you

Nudge (only if you are stuck): (a) Could a species that is not in the key share every feature on the route? (b) Is choosing the statement that fits "best" a fair answer?