The conditions for natural selection

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Two kinds of year for finches on Daphne Major (real pattern from Concepts of Biology and Biology 2e)

   kind of year	scarce seeds	bill size with the higher survival	average bill size afterward
   drought	small, soft seeds, more than large, hard seeds	large-billed	larger
   very wet year	large, hard seeds	small-billed	smaller

2. 1.

   Noah reads two real patterns for finches. Which claim fits both rows?

   • The favored bill size depends on the scarce seeds, so selection can reverse
   • Large bills are the better trait, since large-billed finches survived better in the drought
   • The finch population changed its bills on purpose to match each year's seeds
   • Selection ran in one direction, since the wet year had no effect on bill size

3. Use this

   Agar plate diagram, zones: Zone 1: Start: a sample on a plate with no antibiotic | bacteria cover the plate; Zone 2: Round 1: antibiotic on the plate | colonies from a small share of the bacteria; Zone 3: Round 2: bacteria from the Round 1 colonies, same antibiotic | colonies cover most of the plate.

4. 2.

   Esme reads the plates and the chart together. Which claim fits both?

   • Each bacterium became more resistant with each round it faced
   • Each round of antibiotic caused more bacteria to mutate into resistant ones
   • The few resistant bacteria present at the start multiplied, so resistant bacteria became common
   • The bacteria were identical at the start, so resistance arose in Round 2

5. Moths per 100 (trunks sooty from generation 1 to 5, cleaned after generation 5) (model data)

   moth color	generation 1	generation 5	generation 9
   dark	10	70	15
   light	90	30	85

6. 3.

   Jun sees dark moths rise, then fall. How does natural selection explain both changes?

   • Soot darkened the moths in life, and they passed the dark color on
   • Each moth changed its color back as soon as the soot was gone from the trunks
   • The color matching the trunks survived more, and the trunks changed
   • The moths changed color on purpose each time the trunks changed

7. Finches before and after a drought on a model island (model data)

   bill type	before the drought	survivors
   small-billed	80	8
   large-billed	20	12

8. 4.

   Large-billed finches fell from 20 to 12, yet the average bill size rose. Kira asks how that can be. Which explanation fits?

   • Small-billed finches fell faster, so large-billed finches became a bigger share
   • Some small-billed finches grew larger bills, which raised the large-billed count
   • The finches needed larger bills, so the survivors' bills grew deeper
   • The table must have an error, since a count that falls cannot raise the average

9. Notebook

   Notes on a drought and finch bills (classmate's notebook), 4 lines. Columns: line, entry. Line 1: A drought left far fewer seeds, and small, soft seeds declined more than large, hard seeds. Line 2: Large-billed finches survived better than small-billed finches. Line 3: So each surviving finch's bill grew deeper to match the seeds that remained. Line 4: Bill size is inherited, so later generations had a larger average bill.

10. 5.

    Luz reads a classmate's notebook about a drought and finch bills. Which line has the mistake?

    • Line 1: small, soft seeds should have declined less than large, hard seeds
    • Line 3: a finch's bill does not grow to fit; survivors keep their bills
    • Line 4: bill size is not inherited, so the average could not change
    • Line 2: small-billed finches should have survived better than large-billed ones

11. Notebook

    Notes on bacteria and an antibiotic (classmate's notebook), 4 lines. Columns: line, entry. Line 1: A plate of bacteria was treated with an antibiotic. Line 2: A few colonies grew, and the rest of the bacteria stopped growing. Line 3: The antibiotic caused the surviving bacteria to mutate into resistant forms. Line 4: The resistant bacteria passed the trait to later generations, so they became common.

12. 6.

    Milo reads a classmate's notebook about bacteria and an antibiotic. Which line has the mistake?

    • Line 2: colonies cannot grow on a plate when an antibiotic is present on it
    • Line 4: resistance cannot be passed on to the later generations of bacteria
    • Line 3: the resistance gene was already present; the antibiotic did not cause it
    • Line 1: an antibiotic cannot be used on a plate that holds a sample of bacteria

13. Notebook

    Notes on tall and short plants (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Tall plants got more light and left more seeds than short plants. Line 2: The tall plants were tall because they grew in rich soil. Line 3: Seeds from tall and short plants were grown in one poor soil. Line 4: So generation 2 will be taller on average, because tall plants left more seeds.

14. 7.

    Pia reads a classmate's notebook about tall and short plants. Which line has the mistake?

    • Line 1: more light cannot change how many seeds a plant leaves behind in a season
    • Line 3: seeds from different plants must be grown in different soils to compare them
    • Line 2: rich soil cannot make a plant taller than a plant in poor soil
    • Line 4: soil-made height is not inherited, so generation 2 will not be taller

15. Moths per 100 in a sooty woodland (model data)

    trait	generation 1	generation 2	generation 3
    dark moths	12	30	65
    light moths	88	70	35

16. 8.

    Ren reads the moth table. Which claim and reason fit it?

    • Each moth evolved; light moths gradually darkened over the generations of the study
    • The population evolved; the moths needed to be dark to match the sooty trees
    • The dark moths evolved; they are stronger than light moths and so they are fitter
    • The population evolved; dark moths survived more and the color is inherited

17. Finches per 100 before and after a drought (model data)

    trait	generation 1	generation 2
    large-billed	20	60
    small-billed	80	40

18. 9.

    The drought favored large bills. Tala reads the table and asks where the large bills in generation 2 came from. Which claim and reason fit?

    • The drought changed the finches' genes, since they needed large bills
    • Each small-billed finch grew a large bill during the drought
    • Large bills were already in generation 1; the drought changed their share
    • Finches that strengthened their bills on hard seeds passed on the larger bill

19. Two flasks of bacteria tested on antibiotic plates (model data)

    flask	antibiotic exposure	able to grow with the antibiotic (per 10,000)
    A	none	4
    B	3 rounds	9,000

20. 10.

    Zee reads a model test of two flasks. Which claim and reason fit the table?

    • The antibiotic selected resistance; Flask A, never exposed, already held some resistant bacteria
    • The antibiotic created resistance; Flask B gained it from 3 rounds of exposure
    • Each bacterium in Flask B adjusted to the antibiotic during exposure
    • The bacteria in Flask B mutated because they needed resistance to grow