SOLUTION: Cladogram worksheet practice key - Studypool - Free Printable

Let’s go through each question one by one, using the cladogram provided. We’ll think step by step so you understand how to read a cladogram and answer these questions correctly.

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Question 1: According to your cladogram, which two species are more closely related: worms and spiders or worms and ants? How do you know?

Wait — actually, looking at the cladogram shown in the image (which includes Lancelet, Lamprey, Tuna, Salamander, Turtle, Leopard), there are no worms, spiders, or ants on this particular cladogram. That means Question 1 and Question 2 must be referring to a *different* cladogram that was probably shown earlier in the worksheet — maybe one with insects?

But since we’re told to use “the following cladogram” for questions 4–7, and Questions 1–3 seem to refer to a different diagram (with dragonflies, flies, June bugs, etc.), we should focus only on the cladogram that’s clearly visible here — the one with vertebrates.

So let’s skip Questions 1–3 because they don’t match the given cladogram. The instructions say: “Use the following cladogram to answer the questions below.” And that cladogram starts at Question 4.

Actually — wait! Looking again, the user included answers already written under Questions 1–3. But those answers don’t match the vertebrate cladogram shown. For example, it says “worms and spiders are more closely related” — but worms aren’t even on the vertebrate cladogram. So likely, Questions 1–3 belong to a previous part of the worksheet, and we’re now focusing on the vertebrate cladogram for Questions 4–7.

Since the instruction says: “Use the following cladogram to answer the questions below,” and then shows the vertebrate cladogram, we will assume Questions 4–7 are the ones to solve based on that diagram.

Let’s proceed with Questions 4–7.

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Question 4: What trait separates lampreys from tuna on this cladogram?

Look at the cladogram:

- Lancelet → outgroup
- Then Lamprey branches off after “Vertebral column”
- Then Tuna branches off after “Jaws”

That means: Lampreys have a vertebral column but NO jaws.
Tuna have both vertebral column AND jaws.

So the trait that appears between lamprey and tuna is jaws.

✔ Answer: JAWS

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Question 5: What separates a salamander from a turtle?

Salamander comes after “Four walking legs”
Turtle comes after “Amniotic egg”

So between salamander and turtle, the new trait that appears is amniotic egg.

Salamanders lay eggs without an amnion (they need water), turtles lay amniotic eggs (can live on land).

✔ Answer: AMNIOTIC EGG

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Question 6: Which organism is most related to the leopard?

On a cladogram, the most closely related organism is the one that shares the most recent common ancestor — meaning, the one closest to it on the tree.

Leopard is at the far right. Just before leopard is turtle. They share the same branch point after “Amniotic egg”.

Lamprey, tuna, salamander all branched off earlier.

So turtle is the closest relative to leopard on this cladogram.

✔ Answer: TURTLE

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Question 7: Which organism’s DNA will differ the most from the leopard? Why?

DNA differences usually correlate with how long ago two species shared a common ancestor.

The farther apart two organisms are on the cladogram, the more time has passed since their last common ancestor → more DNA changes → more difference.

Leopard is at the end. The first organism to branch off is the lancelet (outgroup). It doesn’t even have a vertebral column!

So lancelet is the least related to leopard.

Therefore, its DNA will differ the most.

Why? Because it has the fewest traits in common and is farthest away on the cladogram.

✔ Answer: THE LANCELET’S DNA. IT’S THE ORGANISM WITH LEAST TRAITS IN COMMON AND FARTHEST IN THE CLADOGRAM.

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Final Answer:
4. JAWS
5. AMNIOTIC EGG
6. TURTLE
7. THE LANCELET’S DNA. IT’S THE ORGANISM WITH LEAST TRAITS IN COMMON AND FARTHEST IN THE CLADOGRAM.