Clues that living things share ancestors
Grade 7 Science Worksheet
Circle the best answer.
Ari compares the whale flipper and the cat leg. How should the two limbs be classified?
- Analogous, since both limbs move the animal about
- Analogous, since different jobs mean different bones
- Neither, since a flipper and a leg share no bones
- Homologous, since the same bones do different jobs
Esme sees that a bat wing and a cat leg both have a humerus. What does that suggest?
- The two share an ancestor from long ago, since the same bone appears
- The two do the same job, since the same bone appears
- The two are close relatives, since they look alike
- A bat turned into a cat, since the same bone appears
Read this first
Use this
Grand Canyon layers (real data: National Park Service) (real data: National Park Service). Rock-layers diagram, layers never moved, top to bottom. Layer 1 (top): Hermit Formation: ferns and insect remains. Layer 2: Supai Group: tracks of four-legged animals and plant fossils. Layer 3: Redwall Limestone: corals and brachiopods (shelled sea animals). Layer 4 (deepest): Temple Butte Formation: fish.
Jun reads the Grand Canyon layers. Which group of fossils is the oldest of the four?
- The fish in Layer 4, the deepest layer
- The four-legged tracks in Layer 2, near the top
- The ferns and insects in Layer 1, the top layer
- The corals in Layer 3, next to the deepest
Kira compares Layer 4 and Layer 2. What does the order of the fossils show?
- Living fish turned into the animals that made the tracks
- Fish came before the four-legged animals, since Layer 4 lies below Layer 2
- Four-legged animals came before fish, since the higher layer is older
- The two kinds lived at the same time, since both are in the canyon
Use the table
The fossil Tiktaalik (real data: Daeschler, Shubin and Jenkins 2006, Nature) (real data: Daeschler, Shubin and Jenkins 2006, Nature; via BioEd Online). Comparison chart.
Feature What the fossil shows Age 375 million years old Place found Ellesmere Island, Canada Fish-like features bony scales and fins Arm-like features elbow and wrist bones inside the front fin Luz reads the chart of a fossil found on Ellesmere Island. What does this fossil show?
- A fish that grew arm bones during its own life
- A land animal that has no fish features in its body
- A fossil animal with both fish and arm-like features
- A fish alive today that is turning into a land animal
Milo reads the DNA chart. Which kind is the closest relative of Kind 1?
- Kind 4, since it is last in the list
- Kind 4, since a lower match means a closer relative
- Kind 3, since 91 is the middle number
- Kind 2, since its DNA matches Kind 1 the most
Noah reads that Kind 1 and Kind 2 match 98 percent. What does 98 percent mean?
Use the picture in question 6.
- Kind 2 looks 98 percent like Kind 1
- 98 of every 100 compared DNA letters are the same
- Kind 2 is 98 percent as big as Kind 1
- 98 of every 100 body traits are the same in both kinds
Kind 1 and Kind 3 match 91 percent. Pia says 9 percent of Kind 3's body differs from Kind 1. What is right?
Use the picture in question 6.
- Kind 3 has 9 percent fewer traits than Kind 1
- 9 percent of Kind 3's body parts differ from Kind 1's
- 9 of every 100 compared DNA letters differ, not 9 percent of the body
- 91 of every 100 compared DNA letters differ
Four rock layers (model data). Rock-layers diagram, layers never moved, top to bottom. Tala wants a fossil older than the clam shell in Layer 2. Where should Tala dig?
- In Layer 3, since it lies below the clam shell
- In Layer 2, beside the clam shell
- In any layer, since the layers formed together
- In Layer 1, since higher layers are older
Layer 1 holds a grass print and Layer 3 holds a fish scale. Zee says the grass print formed first. What is right?
- Neither can be dated, since fossils do not show age
- The grass print formed first, since the top layer is the oldest
- The fish scale formed first, since Layer 3 lies below Layer 1
- Both formed together, since the layers touch