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?

   • 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
   • 9.0 mm, since each finch shrank its own beak
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
   • 30 per 100, since the moths share one color
   • More than 30 per 100, since matching moths have more young
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 medicine became weaker over time
   • No growth, since the antibiotic stops bacteria of this kind
   • Many colonies, since the 3 colonies came from resistant bacteria
   • Many colonies, since the bacteria became resistant when they met it
4. 4.

   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 medicine wore off in those three spots
   • The bacteria changed to resist it when it touched them
   • A few bacteria in the group could already grow with it
   • The bacteria were alike, so the medicine missed three spots
5. 5.

   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?

   • Natural selection: the weather chose which plants made seeds
   • Artificial selection: the plants grew bigger buds on purpose
   • Artificial selection: people chose which plants made seeds
   • Natural selection: the plants changed to suit the farm
6. 6.

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

   • The plants needed bigger leaves, so leaves grew bigger
   • People chose plants with the flowers or leaves they wanted, over generations
   • Each wild plant changed its leaves to suit farm soil
   • One planting made the new vegetables at once
7. 7.

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

   • A gardener saved seeds from the tallest sunflowers
   • A farmer planted seeds from the curliest kale
   • A class kept seeds from the reddest radishes for a fair
   • Light moths matched pale bark and left more young
8. 8.

   Ren compares the two rows of the moth chart. How many more light moths per 100 were there in 1984 than in 1959?

   • 24 more per 100
   • 6 more per 100
   • 36 more per 100
   • 30 more per 100
9. 9.

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

   • 3.0 mm shallower
   • 0.3 mm shallower
   • 0.7 mm shallower
   • 0.3 mm deeper
10. 10.

    Zee counts colonies on two plates with the same antibiotic. How many times as many colonies grew on Plate 3 as on Plate 2?

    • 450 times as many
    • 50 times as many
    • 5 times as many
    • 147 times as many