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 fern leaf in Layer 1, since the top 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 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 same age as the leaf print, since both are in rock
   • It is the youngest, since the deepest layer formed last
   • It is the oldest, since the deepest layer formed first
   • 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
   • A different bone, since flying needs other bones than swimming
   • No bone, since a wing and a flipper share no bones
   • The humerus, since the same letter marks a matching bone
6. 4.

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

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

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

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

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

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

    • Which DNA letters two animals share
    • Which living animal turned into another living one
    • How alike two living animals look today
    • The order of fossils in rock layers over time
13. 9.

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

    • Chicken, since its early embryo has pharyngeal arches
    • Turtle, since its early embryo has arches and a tail
    • Fish, since its adult column says yes
    • Mouse, since its early embryo has a tail
14. 10.

    Tala reads the same embryo chart. What do all four early embryos share?

    Use the picture in question 9.

    • The same adult body, since the four embryos look alike
    • Gills as adults, since the last column says yes
    • Gills and fins, since the fish row says yes
    • Pharyngeal arches and a tail, since each row says yes