Clues that living things share ancestors

Grade 7 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Use this

   Four rock layers (model data). Rock-layers diagram, layers never moved, top to bottom.

2. 1.

   Ari reads four rock layers that were never moved. Which fossil is the oldest?

   • The fish in Layer 3, since it sits just above the deepest
   • The snail shell in Layer 2, since it sits just below the top
   • The fern leaf in Layer 1, since the top layer is oldest
   • The coral in Layer 4, since the deepest layer is oldest
3. 2.

   Esme says the worm trail in Layer 4 is the youngest fossil. Which statement is right?

   • It is the oldest, since the deepest layer formed first
   • It is the same age as the leaf print, since both are in rock
   • It is the youngest, since the deepest layer formed last
   • It is the same age as the pine cone, since the layers touch

4. Use the table

   Limb bones (letters A, B and C mark matching bones) (real bone names: Understanding Evolution, UC Berkeley; letters are labels). Comparison chart.

   Animal	Bone A	Bone B	Bone C	Job of the limb
   Whale flipper	humerus	radius	ulna	swimming
   Bat wing	?	radius	ulna	flying

5. 3.

   Jun matches bones by letter. Bone A in the whale flipper is the humerus. What is bone A in the bat wing?

   • The ulna, since it is the last bone in the bat row
   • The humerus, since the same letter marks a matching bone
   • No bone, since a wing and a flipper share no bones
   • A different bone, since flying needs other bones than swimming
6. 4.

   Kira matches bones by letter. Bone C in the whale flipper is the ulna. What is bone C in the cat leg?

   • A new bone, since cats walk and whales swim
   • The ulna, since the same letter marks a matching bone
   • The humerus, since it is the first bone in the whole row
   • The radius, since it sits right next to the ulna

7. Use the table

   Limb bones (letters A, B and C mark matching bones) (real bone names: Understanding Evolution, UC Berkeley; letters are labels). Comparison chart.

   Animal	Bone A	Bone B	Bone C	Job of the limb
   Whale flipper	humerus	radius	ulna	swimming
   Bat wing	humerus	radius	ulna	flying

8. 5.

   Luz sees the whale flipper swims and the bat wing flies, yet both have bones A, B and C. What does this show?

   • Limbs with the same bones must have the same job
   • Limbs with the same bones can do different jobs
   • Limbs with different jobs must have different bones
   • Limbs with the same job must have the same bones
9. 6.

   Milo needs a word for body parts built from the same bones that do different jobs. Which word fits?

   • Fossil record
   • Pharyngeal arches
   • Homologous structures
   • Analogous structures
10. 7.

    Two body parts do the same job but have a different build. Noah needs the right word. What is it?

    • Fossil record, since the parts are found in rock layers
    • Analogous structures, since the job matches but the build differs
    • Homologous structures, since the same job shows a shared ancestor
    • Pharyngeal arches, since the parts begin in embryos
11. 8.

    Pia reads the words fossil record on a museum card. What does the fossil record show?

    • Which DNA letters two animals share
    • The order of fossils in rock layers over time
    • How alike two living animals look today
    • Which living animal turned into another living one
12. 9.

    Ren reads the embryo chart. Which animal has gills as an adult?

    • Turtle, since its early embryo has arches and a tail
    • Mouse, since its early embryo has a tail
    • Fish, since its adult column says yes
    • Chicken, since its early embryo has pharyngeal arches
13. 10.

    Zee reads that a mouse embryo and a fish embryo both have pharyngeal arches and a tail. What does that suggest?

    • The two share an ancestor from long ago
    • The mouse will grow gills
    • The two grow up to look alike
    • The mouse came from a living fish