Clues that living things share ancestors
Grade 7 Science Worksheet - Challenge Me
Circle the best answer.
Esme asks why a swimming flipper and a walking cat leg share bones. Which reason fits the chart?
- Both came from a shared ancestor's limb, as the fossils show limbs changing
- A living cat turned into a whale, so they share bones
- Both limbs look alike, so the animals are close relatives
- Both limbs move the animal about, so the two limbs must have the same bones in them
The bird wing and butterfly wing both fly, yet Jun says they are not close relatives. Which explanation fits the chart?
- A living butterfly came from a living bird, since both of them fly
- Same job, different build, so the wings evolved separately
- Same job, so the animals share a recent ancestor
- Different build, so the wings must do different jobs
Kira reads the wing chart. Which two animals does it link most closely, and why?
Use the picture in question 2.
- Bat and butterfly, since both wings work in flight
- Bird and bat, since their wings share the same forelimb bones
- Bird and butterfly, since both wings are used for flying
- Bird, bat and butterfly equally, since each wing has the same job
Luz reads two results on the wing chart, the job and the bones. Which is better evidence of a shared ancestor?
Use the picture in question 2.
- The job, since bones follow the job
- The bones, since matching parts come from a shared ancestor
- The job, since animals that fly share a recent common ancestor
- Neither, since a chart cannot show ancestry
Read this first
Use the table
Three stretches of DNA that chicken and turkey both have (real data: Dalloul et al. 2010, PLoS Biology; percents are about) (real data: Dalloul et al. 2010, PLoS Biology). Comparison chart.
DNA stretch Length (letters) Chicken and turkey match (percent) CR1_B 2,000 91 Birddawg_I 3,600 89 Galluhop 1,200 91 Milo says: Chicken and turkey match in 91 percent of their body traits. What is the flaw?
- The flaw is that 91 percent is too low to show any link
- The flaw is that chicken and turkey are the same animal
- No flaw, since a high DNA percent means most traits match
- The 91 percent counts matching DNA letters in one stretch, not body traits
Noah says: Chicken and turkey match about 91 percent in DNA, so a chicken turned into a turkey. What is the flaw?
- The flaw is that the longest stretch should match 100 percent
- No flaw, since a close DNA match means that one kind became the other kind
- A DNA match shows a shared ancestor, not one kind turning into the other
- The flaw is that DNA cannot show how kinds are related
“layers never moved” Pia says: The moth wing print is in Layer 1, the top layer, so it is the oldest fossil. What is the flaw?
- The top layer is the youngest, so the moth wing print is the youngest
- No flaw, since layers on top formed first
- The flaw is that the crab shell should be the youngest
- The flaw is that fossils in one quarry share an age
Ren reads the embryo chart. Which claim and reason fit best?
- A shared ancestor, since all three early embryos have the same parts
- Unrelated animals, since the adults differ in gills
- The same kind of animal as adults, since the early embryos look much alike
- A living shark became a rabbit, since the early parts match
Three rock layers (model data). Rock-layers diagram, layers never moved, top to bottom. Tala reads the rock layers. Which claim and reason fit best?
- Fins and limbs formed together, since the layers touch
- Limbs came from fins, since older layers hold fins and newer ones hold limbs
- Fins came from limbs, since deeper layers are younger
- One fish grew limbs during its own life, since Layer 2 has arm-like bones in its fins
Zee reads the DNA chart. Which claim and reason fit best?
- Neither kind is closer to Kind 5, since a percent says nothing about relatives
- Kind 6 is closer to Kind 5, since more DNA letters match
- Kind 7 is closer to Kind 5, since fewer DNA letters match
- Kind 6 shares 97 percent of body traits with Kind 5, since the percent counts traits