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 finch population changed its bills on purpose to match each year's seeds
   • 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
   • 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 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
   • Each bacterium became more resistant with each round it faced
5. 3.

   From generation 3 on, large, hard seeds were plentiful again. Ari sees the trend toward small bills stop. What explains the stop?

   • Small bills lost their survival advantage, so selection stopped pushing one way
   • The finches stopped changing because they had gotten the bills they needed to survive
   • The small-billed trait stopped being inherited after generation 3, when large seeds returned
   • Each finch's bill stopped changing once the large seeds returned to the island

6. 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

7. 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
   • The finches needed larger bills, so the survivors' bills grew deeper
   • Some small-billed finches grew larger bills, which raised the large-billed count
   • The table must have an error, since a count that falls cannot raise the average

8. 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.

9. 5.

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

   • Line 3: a finch's bill does not grow to fit; survivors keep their bills
   • Line 1: small, soft seeds should have declined less than large, hard seeds
   • 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

10. 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.

11. 6.

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

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

12. 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.

13. 7.

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

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

14. 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

15. 8.

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

    • The population evolved; the moths needed to be dark to match the sooty trees
    • Each moth evolved; light moths gradually darkened over the generations of the study
    • 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

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

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

17. 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?

    • Finches that strengthened their bills on hard seeds passed on the larger bill
    • 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

18. 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

19. 10.

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

    • The bacteria in Flask B mutated because they needed resistance to grow
    • 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 antibiotic selected resistance; Flask A, never exposed, already held some resistant bacteria