How helpful traits become more common over many generations

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

   A wet year left many small seeds and few large, hard seeds. Ari predicts the next generation's average beak depth. Which prediction fits?

   • 9.0 mm, since each finch shrank its own beak
   • 6.0 mm, since the whole group changed in one generation
   • 9.1 mm, since small-beaked finches had more young
   • 9.4 mm, since the finches share one beak depth
2. 2.

   Light moths rose from 6 to 30 per 100 as clean-air laws lightened the bark. Bo predicts the next years if the bark stays light. What fits?

   • 100 per 100 by next year, in a single step
   • Back to 6 per 100, since moths change color each year
   • More than 30 per 100, since matching moths have more young
   • 30 per 100, since the moths share one color
3. 3.

   Esme spreads bacteria from the 3 colonies on Plate 2 onto a new plate with the same antibiotic. What will Plate 3 most likely show?

   • Many colonies, since the 3 colonies came from resistant bacteria
   • Many colonies, since the medicine became weaker over time
   • No growth, since the antibiotic stops bacteria of this kind
   • Many colonies, since the bacteria became resistant when they met it
4. 4.

   Jun reads the moth chart. From 1959 to 1984, light moths went from 6 to 30 per 100 as trees regained their pale look. What explains it?

   • Dark moths turned light to match the bark
   • The cleaner air made the moths grow lighter
   • Light moths matched the bark, so more survived and had young
   • The whole group switched to light in one year
5. 5.

   Kira reads the finch chart. After the wet year, the average beak depth fell from 9.4 mm to 9.1 mm. What explains it?

   • Small-beaked finches had more young, so the average fell
   • Each finch's beak shrank to fit the small seeds
   • The wet weather made the beaks grow smaller
   • The whole group had smaller beaks after one season
6. 6.

   Lab plates with an antibiotic (model data). On Plate 2 the antibiotic stopped most growth, but 3 colonies grew. Luz explains the 3 colonies. Which explanation fits?

   • The bacteria were alike, so the medicine missed three spots
   • The medicine wore off in those three spots
   • A few bacteria in the group could already grow with it
   • The bacteria changed to resist it when it touched them
7. 7.

   Milo reads that farmers saved seeds from wild cabbage plants with the biggest flower buds and replanted them, year after year. Which kind of selection is this?

   • Artificial selection: the plants grew bigger buds on purpose
   • Artificial selection: people chose which plants made seeds
   • Natural selection: the weather chose which plants made seeds
   • Natural selection: the plants changed to suit the farm
8. 8.

   Noah reads that broccoli and kale both came from one wild cabbage plant. How did two different vegetables come from it?

   • Each wild plant changed its leaves to suit farm soil
   • The plants needed bigger leaves, so leaves grew bigger
   • People chose plants with the flowers or leaves they wanted, over generations
   • One planting made the new vegetables at once
9. 9.

   Pia sorts cases into natural selection and artificial selection. Which case is natural selection?

   • A class kept seeds from the reddest radishes for a fair
   • A farmer planted seeds from the curliest kale
   • Light moths matched pale bark and left more young
   • A gardener saved seeds from the tallest sunflowers
10. 10.

    Tala compares the finch generations after the wet year. How did the average beak depth change from Generation 1 to Generation 2?

    • 0.3 mm shallower
    • 0.7 mm shallower
    • 0.3 mm deeper
    • 3.0 mm shallower