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?
- 2: it has the smallest cost, 2
- 32: it has the largest benefit, 36
- 16: benefit 32 is large and cost 22 is moderate
- 8: benefit minus cost is 26 − 11 = 15, the largest net gain
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?
- 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
- Test 4 fish in a smaller tank to see what crowding does
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 19%: the average gap is 0.38 × 28 + 0.62 × 55 ≈ 45 °C, against 55 °C
- About 38%: the share of time huddling
- About 49%: huddling cuts the gap from 55 °C to 28 °C
- About 81%: the heat that is still lost
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?
- No study: a gap of 20 points is too small to count
- Study C: 200 fish per condition is the biggest sample, so it must settle the question
- Study A: its 40-point gap is the biggest
- Study B: random assignment and 100 fish per condition give a fair, steady comparison
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 1: heat loss depends on the air temperature alone, not on a gap
- Line 4: 18 ÷ 21 should be written as 21 ÷ 18
- 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
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 1: the angle shows the kind of resource, not the direction
- Line 4: the patch stays put, but the angle shrinks as the sun moves
- Line 2: the sun should move 30° each hour
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 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
- Line 2: a spread cannot be larger than the average
Flocks and visits (model data)
flock size visits a day chance one bird is lost in a day (%) 10 1 10 100 4 4 1000 16 1.6 Ren's friend says a flock's risk falls in proportion to its size. Which reply uses the table best?
- Disagree: bigger flocks are riskier, since visits rise from 1 to 16
- Agree: 4% is half of 10%, so doubling the flock halves the risk
- Agree: the risk is shared out evenly, so a flock 10 times larger has 10 times less risk each
- Disagree: more visits arrive, so a flock 10 times larger cut the risk only from 10% to 4%
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: 160 nests rear 288 chicks in total against 30 in the small colony, so the big colony wins
- Agree: 1.8 chicks per nest is still a benefit, so the group helps
- Disagree: the table cannot say anything about benefits
- Disagree: chicks per nest fall from 3.0 to 1.8, so crowding costs more than the group gives here
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