How living in groups helps animals survive

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   A colony with and without a sentinel (model data)

   measure	with a sentinel	no sentinel
   seconds until the colony hears a warning	4	12
   the sentinel's chance of being lost each day (%)	3	not on duty
   any other member's chance of being lost each day (%)	1	1

2. 1.

   Ari reads model data on a meerkat colony. Which conclusion about sentinel duty is best supported?

   • The colony gains and no member pays, since the colony is warned in 4 s
   • The sentinel carries 3 percentage points more risk than the others
   • The colony gains a warning in 4 s instead of 12 s, but the sentinel carries 3 times the risk
   • The sentinel gains the most, since it spots the threat first and can reach cover before the others

3. Minnows in same-size tanks (model data)

   group size	share surviving at day 10 (%)
   4	70
   8	85
   16	90
   32	75

4. 2.

   Jun thinks crowding in a fixed tank lowered survival at 32 fish. Which new test would best check that explanation?

   • Test 4 fish in a smaller tank to see what crowding does
   • Add extra food to the tank of 4 fish and compare
   • Keep 32 fish per tank, but test tanks of two sizes with the same water and light
   • Repeat with 16 fish in the same tank to see the 90% result again and confirm the rise

5. Scatter of the place a dance advertises (model data)

   resource	distance (m)	spread of the place (m)
   near patch	200	30
   far patch	600	?

6. 3.

   Bo reads the model data. The angle's precision stays the same at any distance. How much wider is the zone to search at 600 m, and why?

   • 3 times wider: the same angle error covers a wider strip at a longer distance
   • The same width at any distance, since the angle's precision is the same for near and far patches
   • 3 times wider, since angle precision gets worse with distance
   • 9 times wider, since both the distance and the width triple

7. Use the table

   A male's day (model rule: heat lost is proportional to the gap from 38 °C; shares from Gilbert et al. 2006) (model data and Gilbert et al. 2006)

   situation	share of time	air temperature (°C)
   huddling	38%	10
   not huddling	62%	−17

8. 4.

   Luz compares a male's average heat loss with never huddling. By about what percent did huddling cut it?

   • About 49%: huddling cuts the gap from 55 °C to 28 °C
   • About 19%: the average gap is 0.38 × 28 + 0.62 × 55 ≈ 45 °C, against 55 °C
   • About 81%: the heat that is still lost
   • About 38%: the share of time huddling

9. Three studies of fish (model data)

   study	fish per condition	how fish got their condition	survivors in groups	survivors alone
   study A	5	assigned at random	5	3
   study B	100	assigned at random	80	60
   study C	200	fish chose	170	110

10. 5.

    Zee compares three model studies of fish in groups and alone. Which gives the strongest evidence that groups raise survival?

    • Study C: 200 fish per condition is the biggest sample, so it must settle the question
    • No study: a gap of 20 points is too small to count
    • Study A: its 40-point gap is the biggest
    • Study B: random assignment and 100 fish per condition give a fair, steady comparison

11. Notebook

    Notes on a model huddle (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Heat lost is proportional to the gap between a bird's 38 °C and the air. Line 2: In −17 °C air the gap is 38 − 17 = 21 °C. Line 3: In a 20 °C pocket the gap is 38 − 20 = 18 °C. Line 4: So the pocket bird loses 18 ÷ 21, about 86%, as much heat.

12. 6.

    Ari reads a classmate's notebook about a model huddle. Which line has the mistake?

    • Line 3: the gap in a 20 °C pocket should be 38 + 20 = 58 °C
    • Line 2: the gap from 38 °C down to −17 °C is 38 + 17 = 55 °C
    • Line 4: 18 ÷ 21 should be written as 21 ÷ 18
    • Line 1: heat loss depends on the air temperature alone, not on a gap

13. Notebook

    Notes on a patch at 220° (classmate's notebook), 4 lines. Columns: line, entry. Line 1: At 12:00 the sun is at 180°, so the dancer shows 220 − 180 = 40° clockwise. Line 2: The sun moves 15° clockwise each hour. Line 3: At 14:00 the sun is at 210°, so the dancer shows 220 − 210 = 10°. Line 4: So the angle stays at 40° all day, because the patch has not moved.

14. 7.

    Kira reads a classmate's notebook about a model dance. Which line has the mistake?

    • Line 4: the patch stays put, but the angle shrinks as the sun moves
    • Line 1: the angle shows the kind of resource, not the direction
    • Line 3: the angle should be 210 − 220 = −10°
    • Line 2: the sun should move 30° each hour

15. Notebook

    Notes on emperor penguin huddles (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Loggers were fitted to 8 birds. Line 2: A huddle lasted 1.6 h on average, with a spread of 1.7 h. Line 3: So most huddles lasted close to 1.6 h. Line 4: Males huddled 38% of their time.

16. 8.

    Milo reads a classmate's notebook about the Gilbert study. Which line has the mistake?

    • Line 1: 8 birds are too few for any conclusion
    • Line 3: a spread of 1.7 h, bigger than the average, means lengths varied widely
    • Line 2: a spread cannot be larger than the average
    • Line 4: 38% of their time means one huddle lasted 38% of the whole winter, which is far too long

17. Colony size and chicks (model data)

    nests in the colony	chicks surviving per nest
    10	3.0
    40	2.5
    160	1.8

18. 9.

    Tala claims living in a group helps every species. Which reply fits the model table?

    • Agree: 160 nests rear 288 chicks in total against 30 in the small colony, so the big colony wins
    • Disagree: chicks per nest fall from 3.0 to 1.8, so crowding costs more than the group gives here
    • Disagree: the table cannot say anything about benefits
    • Agree: 1.8 chicks per nest is still a benefit, so the group helps

19. Use the table

    What the huddling study found (data: Gilbert et al. 2006)

    finding	value
    average length of one huddle	1.6 h
    huddles	discontinuous and variable in length
    access to the warmth of huddles	equal for all birds
    huddling time above 20 °C	13%

20. 10.

    Zee claims edge birds in a huddle never get warm. Which reply fits the study?

    • Not supported: the study found birds were never cold
    • Supported: huddles were uneven in size and length, so the edge birds must stay cold the whole time
    • Not supported: huddles were short and changing, and every bird had equal access to warmth
    • Supported: only 13% of huddling time was above 20 °C