1. How is the degree of evolutionary relatedness between two organisms primarily determined using a phylogenetic tree?
- A. By counting the number of physical similarities between the two organisms.
- B. By identifying the most recent common ancestor the two organisms share.
- C. By measuring the distance between their names at the top of the tree diagram.
- D. By comparing the physical environments in which the two organisms currently live.
2. If biologists state that two species are very closely related, what does this imply about their common ancestor?
- A. It was physically identical to both modern species.
- B. It lived a relatively short time ago.
- C. Their common ancestor is still alive today in an unchanged form.
- D. They do not share an ancestor with any other species.
3. A scientist is comparing a bird, a bat, and a crocodile. The 'bird-crocodile' common ancestor lived more recently than the 'bird-bat' common ancestor. Which pair is most closely related?
- A. The bird and the bat, because they both can fly.
- B. The bird and the crocodile.
- C. The bat and the crocodile.
- D. All three are equally related to one another.
4. Imagine Species X and Y have a common ancestor that lived 10 million years ago. Species Y and Z have a common ancestor that lived 20 million years ago. Which statement accurately describes their relationship?
- A. Species X and Z are most closely related.
- B. All three species are equally related.
- C. Species Y is more closely related to Species X because their common ancestor is more recent.
- D. Species Z is the ancestor of both Species X and Y.
5. On a phylogenetic chart, the branch for 'dolphin' is drawn next to the branch for 'shark'. What does this physical proximity on the page indicate about their evolutionary relationship?
- A. It proves they are in the same evolutionary family.
- B. It shows they evolved at the same time.
- C. Nothing definitive; relatedness is found by tracing branches to a common ancestor.
- D. It means they are more closely related than either is to a fish.
6. In a standard evolutionary tree, what does the vertical position of a node, or branching point, primarily indicate?
- A. The geographical location where the species lived.
- B. The time of an evolutionary split.
- C. The physical size of the common ancestor.
- D. The number of genetic mutations that have occurred.
7. If you trace the lineages of two different species on an evolutionary tree and find that they connect at a node very close to the bottom, what does this signify?
- A. The species are not related in any way.
- B. Their common ancestor is very ancient.
- C. One species evolved directly from the other one very recently.
- D. The species had a common ancestor that was physically very large.
8. A student looking at an evolutionary tree incorrectly concludes that two species are distantly related because their connecting node is near the top. What is the student's misunderstanding?
- A. The student is reversing the time axis of the tree.
- B. The student thinks horizontal distance, not vertical position, represents relatedness.
- C. The student assumes that all species at the top of the tree are unrelated.
- D. The student is correctly interpreting the tree, as a high node means a distant relationship.
9. Imagine three species: lions, tigers, and turtles. The node connecting lions and tigers is very high on the tree, while the node connecting the lion-tiger group to turtles is very low. Which statement is accurate?
- A. Turtles are the most recent common ancestor of lions and tigers.
- B. The lion-tiger common ancestor is more recent than the ancestor shared with turtles.
- C. The common ancestor of all three animals is represented by the highest node on the tree.
- D. Lions and turtles split from a common ancestor more recently than lions and tigers did.
10. An evolutionary tree shows that the common ancestor for species X and Y is represented by a node near the top. The common ancestor for species X and Z is represented by a node near the bottom. What can be concluded?
- A. Species X is more closely related to species Z than to species Y.
- B. Species Y and Z are equally related to species X.
- C. Species X is more closely related to species Y than to species Z.
- D. Species X and Y lived in different time periods.