Predation, Herbivory and Trophic Cascades · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Hunters, herds, and ripple effects

Science · Ecology & Conservation · ages 21-22
Name ______________________   Date ____________

  1. What is herbivory?

    • Animals eating plants
    • Predators eating predators
    • Plants eating insects

  2. In the lynx and hare cycle, how do the predator numbers relate to prey numbers?

    • Predators peak long before prey
    • Both peak in the same month always
    • Predators lag 1 to 2 years behind prey

  3. In a predator prey cycle, the prey peak comes before the predator peak.

    Circle one:   True   False

  4. Wolves return to that valley. What follows?

    • Deer surge further and trees vanish
    • Trees decline while deer stay flat
    • Deer shrink and trees recover

  5. Wolves leave a valley. What happens to deer and young trees?

    • Deer vanish and trees double
    • Deer surge and young trees decline
    • Nothing changes at any level

  6. Adding fertilizer lifts plants, herbivores, and predators together. What kind of control is that?

    • Bottom-up control
    • Top-down control
    • No control at all

  7. Removing a top predator can only affect its direct prey, never plants two links away.

    Circle one:   True   False

  8. A student fences predators out of one meadow but keeps no control plot. What is missing?

    • More predators inside the fence
    • A comparison meadow to rule out weather and seasons
    • A count of only the plants
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Hunters, herds, and ripple effects W1-mt_T0jG4YImZp-s1

  1. Animals eating plants · Herbivores graze plants down the way predators hunt prey.
  2. Predators lag 1 to 2 years behind prey · Predators rise on abundant hares and starve after hares crash, so they trail behind.
  3. True · Predators need the prey boom first, so their peak always follows.
  4. Deer shrink and trees recover · Each effect reverses direction when the top link is restored.
  5. Deer surge and young trees decline · Predator down means herbivore up means plants down: alternate each arrow.
  6. Bottom-up control · When extra resources at the base lift every level, the limit sits at the bottom.
  7. False · Cascades travel link by link, so plants two steps down feel the removal.
  8. A comparison meadow to rule out weather and seasons · Without an untouched plot, any prey rise could come from a kind year rather than the fence.
Worksheet · LightMySky