Clues that living things share ancestors

Grade 7 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Four rock layers (model data). Rock-layers diagram, layers never moved, top to bottom. Ari reads four rock layers that were never moved. Which fossil is the oldest?

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

2. Read this first

   Use this

   Four rock layers (model data). Rock-layers diagram, layers never moved, top to bottom. Layer 1 (top): leaf print. Layer 2: clam shell. Layer 3: fish scale. Layer 4 (deepest): sponge.

3. 2.

   Bo lists the fossils from oldest to youngest. Which list is in the right order?

   • Fish scale, sponge, leaf print, clam shell
   • Sponge, fish scale, clam shell, leaf print
   • Leaf print, clam shell, fish scale, sponge
   • Sponge, clam shell, fish scale, leaf print
4. 3.

   Four rock layers (model data). Rock-layers diagram, layers never moved, top to bottom. Esme says the worm trail in Layer 4 is the youngest fossil. Which statement is right?

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

5. 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

6. 4.

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

   • 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
   • The ulna, since it is the last bone in the bat row
7. 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 different jobs must have different bones
   • Limbs with the same bones must have the same job
   • Limbs with the same job must have the same bones
   • Limbs with the same bones can do different jobs
8. 6.

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

   • Analogous structures
   • Fossil record
   • Homologous structures
   • Pharyngeal arches
9. 7.

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

   • Homologous structures, since the same job shows a shared ancestor
   • Analogous structures, since the job matches but the build differs
   • Fossil record, since the parts are found in rock layers
   • Pharyngeal arches, since the parts begin in embryos
10. 8.

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

    • The order of fossils in rock layers over time
    • Which DNA letters two animals share
    • Which living animal turned into another living one
    • How alike two living animals look today
11. 9.

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

    • Chicken, since its early embryo has pharyngeal arches
    • Fish, since its adult column says yes
    • Turtle, since its early embryo has arches and a tail
    • Mouse, since its early embryo has a tail
12. 10.

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

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