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?

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

3. Two plants in one season (model data)

   plant	seeds made	survived to breed
   P	40	6
   Q	10	5

4. 2.

   Bo compares fitness, the number of offspring that survive to breed, for two plants. Which plant has the higher fitness, and why?

   • Plant Q: half of its seeds survived, a larger share than P's
   • Plant P: it made the most seeds, which shows it is the strongest
   • Plant P: 6 offspring survived to breed, more than Q's 5
   • Neither: fitness cannot be compared without a height for each plant
5. 3.

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

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

6. 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

7. 4.

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

   • 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
   • Soot darkened the moths in life, and they passed the dark color on

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

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 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
    • Line 1: an antibiotic cannot be used on a plate that holds a sample of bacteria

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 3: seeds from different plants must be grown in different soils to compare them
    • Line 4: soil-made height is not inherited, so generation 2 will not be taller

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
    • The population evolved; dark moths survived more and the color is inherited
    • 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

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?

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

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