Dichotomous Keys

An illustration of two fish is provided. Which paired statements could be used to distinguish the fish using a dichotomous key?

• Eyes on side of head 
  Eyes on top of head
• One set of dorsal fins 
  Two sets of dorsal fins
• Mouth at front of head 
  Mouth on underside of head
• Rounded caudal fin 
  Forked caudal fin

An illustration of four leaves and a dichotomous key are provided. Use the dichotomous key to identify which of the leaves is from a magnolia tree.

• Leaf 1
• Leaf 2
• Leaf 3
• Leaf 4

A table of arachnid and insect characteristics is shown. Which characteristic could be used to distinguish between arachnids and insects?

• Jointed legs
• Body segments
• Presence of eyes
• Presence of antennae

A botanist discovers a new plant in the jungle. Which of the following observations of the plant’s characteristics would be useful in determining its identity with a dichotomous key?

• It was discovered in the summertime.
• It is wet from a recent rain storm.
• Its leaves curl up on the edges.
• It is eaten by native jungle ants.

An illustration of three beetles is given. A student examines three different species of beetles that are related. What structure is identical in all three beetle species?

• Antennae length
• Placement of eyes
• Markings on abdomen
• Width of thorax

A dichotomous key is provided. A fish is caught that has eyes on the side of its head and a wide body covered in spots. What kind of fish is this?

• Cornetfish
• Flounder
• Puffer fish
• Snapper

An illustration of an organism and a dichotomous key are given. What is the organism?

• Arachnid
• Dragonfly
• Fruit fly
• Mayfly

A dichotomous key for trees is provided. Hikers found a tree that has large brown cones and single sharp needles. What species of tree have the hikers found?

• Juniper
• Pine
• Spruce
• Fir

Which of the following characteristics will most likely be helpful in identifying a butterfly using a dichotomous key?

• Migrates north every spring.
• Hangs on branches to rest.
• Flutters wings faster on hot days.
• Hind wings have tail extensions.

A dichotomous key for insects is given. To what order does an insect with two pairs of scaly wings belong?

• Coleoptera
• Diptera
• Heteroptera
• Lepidoptera