When one population changes
Remove one species and the effects spread further than anyone expects — Yellowstone's wolves are the classic case.
Part of your national curriculum
- Biology: interactions and interdependencies: Understand the interdependence of organisms in an ecosystem, including food webs and insect pollinated crops
- Biology: interactions and interdependencies: Understand how organisms affect, and are affected by, their environment, including the accumulation of toxic materials
Lesson overview
What you'll learn in this lesson
Describe the effect of changes in population size
Key learning points
- • Predator and prey cycles
- • Cascades
This lesson at a glance
- 25 minutes
- 12 parts to scroll through
- 3 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 12
Visual introductionPicture this
When one population changes
Remove one species and the effects spread further than anyone expects — Yellowstone's wolves are the classic case.
In a nutshell
Describe the effect of changes in population size
Explore the idea
Part 2 of 12
Learn
Predator and prey cycles
Prey numbers rise, predators follow, prey fall, predators fall. The two curves chase each other with a lag.
Explore the idea
Part 3 of 12
Learn
Cascades
A change at the top can reshape vegetation and even landforms. Interdependence means no species can be removed cleanly.
Reset break
Part 4 of 12
Pause
That's sitting 1 of 3 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Quick check
Part 5 of 12
Quick check
Part 6 of 12
Quick check
Part 7 of 12
Reset break
Part 8 of 12
Pause
That's sitting 2 of 3 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Challenge round
Part 9 of 12
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Challenge round
Part 10 of 12
Game · Recall cards
An arrow in a food chain points…
Card 1 of 4
Mastery quiz
Part 11 of 12
Marked quiz
End of lesson quiz: When one population changes
4 questions, marked with the reasoning shown. No timer.
1. An arrow in a food chain points…
2. Roughly how much energy passes to the next trophic level?
3. Removing a top predator most likely…
4. Roughly how much energy passes to the next level?
Lesson round-up
Part 12 of 12
Lesson round-up
Ready when you are
Quiz score
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Points this lesson
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Best run
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Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?
Ask LunaPart 1 of 12 · Watch & discover
How this is going
- Not looked at yet
Understand the interdependence of organisms in an ecosystem, including food webs and insect pollinated crops
- Not looked at yet
Understand how organisms affect, and are affected by, their environment, including the accumulation of toxic materials