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
   • 9.0 mm, since each finch shrank its own beak
   • 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?

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

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

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

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

   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
   • Natural selection: the plants changed to suit the farm
   • Artificial selection: people chose which plants made seeds
7. 7.

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

   • A farmer planted seeds from the curliest kale
   • A gardener saved seeds from the tallest sunflowers
   • 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
   • 36 more per 100
   • 6 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
   • 0.7 mm shallower
   • 0.3 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
    • 5 times as many
    • 50 times as many
    • 147 times as many