How living in groups helps animals survive
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Benefit and cost of group size (model data)
group size benefit: risk saved (units) cost: competition (units) 2 10 2 4 18 5 8 26 11 16 32 22 32 36 40 Esme reads model data. The best group size has the largest benefit minus cost. Which size is best?
- 8: benefit minus cost is 26 − 11 = 15, the largest net gain
- 2: it has the smallest cost, 2
- 16: benefit 32 is large and cost 22 is moderate
- 32: it has the largest benefit, 36
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 Ari reads model data on a meerkat colony. Which conclusion about sentinel duty is best supported?
- The sentinel carries 3 percentage points more risk than the others
- The colony gains and no member pays, since the colony is warned in 4 s
- The sentinel gains the most, since it spots the threat first and can reach cover before the others
- The colony gains a warning in 4 s instead of 12 s, but the sentinel carries 3 times the risk
Minnows in same-size tanks (model data)
group size share surviving at day 10 (%) 4 70 8 85 16 90 32 75 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
- Repeat with 16 fish in the same tank to see the 90% result again and confirm the rise
- 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
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 Luz compares a male's average heat loss with never huddling. By about what percent did huddling cut it?
- About 81%: the heat that is still lost
- About 19%: the average gap is 0.38 × 28 + 0.62 × 55 ≈ 45 °C, against 55 °C
- About 49%: huddling cuts the gap from 55 °C to 28 °C
- About 38%: the share of time huddling
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 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 B: random assignment and 100 fish per condition give a fair, steady comparison
- Study A: its 40-point gap is the biggest
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.
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
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.
Kira reads a classmate's notebook about a model dance. Which line has the mistake?
- Line 3: the angle should be 210 − 220 = −10°
- Line 2: the sun should move 30° each hour
- 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
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.
Milo reads a classmate's notebook about the Gilbert study. Which line has the mistake?
- Line 2: a spread cannot be larger than the average
- Line 1: 8 birds are too few for any conclusion
- Line 4: 38% of their time means one huddle lasted 38% of the whole winter, which is far too long
- Line 3: a spread of 1.7 h, bigger than the average, means lengths varied widely
Colony size and chicks (model data)
nests in the colony chicks surviving per nest 10 3.0 40 2.5 160 1.8 Tala claims living in a group helps every species. Which reply fits the model table?
- Agree: 1.8 chicks per nest is still a benefit, so the group helps
- 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
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% 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: only 13% of huddling time was above 20 °C
- Not supported: huddles were short and changing, and every bird had equal access to warmth
- Supported: huddles were uneven in size and length, so the edge birds must stay cold the whole time