Good Learning Co.
SavannahYear 8
← Science
ScienceAnimals in ecosystems30 min★★★ difficulty

Food webs and interdependence

Remove one animal and the effects rarely stop there. Food webs are a way of predicting what happens next.

Lesson overview

What you'll learn in this lesson

Understand the interdependence of organisms in an ecosystem, including food webs and insect pollinated crops

Key learning points

  • • Producers hold everything up
  • • Energy is lost at each step
  • • Knock-on effects
  • • Insect pollinated crops

This lesson at a glance

  • 30 minutes
  • 19 parts to scroll through
  • 4 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

interdependenceorganismsecosysteminsectpollinated

Scroll down — the lesson carries on below

Part 1 of 19 · Discover5%
1

Watch & discover

Part 1 of 19

Watch first

Food webs and interdependence

An English teaching video on this topic from Revision Monkey. Watch it, then scroll down for the lesson.

In a nutshell

Understand the interdependence of organisms in an ecosystem, including food webs and insect pollinated crops

2

What you already know

Part 2 of 19

Before we start

What you already know

You should already know that plants make their own food and that energy passes along food chains.

3

Key words

Part 3 of 19

Key words

Words you'll need today

Producer
An organism that makes its own food by photosynthesis.
Consumer
An organism that eats other organisms.
Decomposer
An organism that breaks down dead material and returns nutrients.
Interdependence
Species relying on one another within an ecosystem.
Pollinator
An animal that carries pollen between flowers.
4

Learning cycle

Part 4 of 19

Learning cycle 1 of 2

Reading a food web

A short piece of teaching, then a check to make sure it has landed.

5

Explore the idea

Part 5 of 19

Learn

Producers hold everything up

Almost every food chain starts with a producer using sunlight. Consumers are then labelled by position: primary consumers eat producers, secondary consumers eat primary consumers, and so on. Decomposers work on everything that dies, returning nutrients so producers can grow again.

6

Explore the idea

Part 6 of 19

Learn

Energy is lost at each step

Only a fraction of the energy at one level reaches the next, because organisms respire, move, keep warm and lose material in waste. That is why there are far fewer top predators than herbivores, and why food chains are rarely more than five links long.

7

Quick check

Part 7 of 19

Quick check

In a food web, the arrows show

8

Quick check

Part 8 of 19

Quick check

Why are there fewer top predators than herbivores?

9

Reset break

Part 9 of 19

Pause

That's sitting 1 of 2 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.

Stop here for now
10

Learning cycle

Part 10 of 19

Learning cycle 2 of 2

Knock-on effects and pollination

A short piece of teaching, then a check to make sure it has landed.

11

Explore the idea

Part 11 of 19

Learn

Knock-on effects

If snow leopards disappear, wild sheep and goat numbers can rise, grazing pressure increases, plant cover thins and soil erodes on steep ground. Predators are not optional extras; they regulate the populations below them.

12

Explore the idea

Part 12 of 19

Learn

Insect pollinated crops

Around three quarters of leading food crops benefit from animal pollination. Bees, hoverflies and moths move pollen between flowers, so pesticide use, hedgerow loss and disease in pollinators feed straight through into human food supply. Interdependence includes us.

13

Quick check

Part 13 of 19

Quick check

Removing snow leopards from a mountain ecosystem could lead to

14

Quick check

Part 14 of 19

Quick check

Insect pollinated crops matter to humans because

15

Common mix-ups

Part 15 of 19

Common mix-ups

Things people often get wrong

  • Arrows in a food web show energy flow, so they point from the eaten to the eater.
  • Losing a predator does not simply mean more of everything below it — grazing damage can reduce plants.
  • Decomposers are not producers; they release nutrients rather than making food from sunlight.
16

Challenge round

Part 16 of 19

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

17

Challenge round

Part 17 of 19

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

Only a fraction of the energy at one level reaches the next, because ____ respire, move, keep warm and lose material in waste.

____ includes us.

18

Mastery quiz

Part 18 of 19

Marked quiz

End of lesson quiz: Food webs and interdependence

6 questions, marked with the reasoning shown. No timer.

  1. 1. A primary consumer eats

  2. 2. Decomposers return

  3. 3. Food chains are rarely longer than about five links because

  4. 4. Interdependence means species

  5. 5. Which would most reduce pollination of crops?

  6. 6. Producers are organisms that

19

Lesson round-up

Part 19 of 19

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 19 · Watch & discover

Good Learning Co. — personalised UK curriculum learning, built around what each learner loves.