ScienceEcosystems and variation30 min★★★ difficulty

Food webs, pollinators and interdependence

Remove one species and things you did not expect start to change. This lesson is about how tightly organisms depend on each other - including the insects that pollinate a large share of our crops.

Part of your national curriculum

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

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

• Webs, not chains
• Predicting a knock-on effect
• Insect-pollinated crops
• Other kinds of dependence

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%

Watch & discover

Part 1 of 19

Watch first

Food webs, pollinators and interdependence

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

Do it for real

The practicals below use what the film shows, with a full method you can follow at home.

Who lives in one square of ground?

In a nutshell

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

What you already know

Part 2 of 19

Before we start

What you already know

You should be able to read a food chain from producer to top consumer.

Recap: Aerobic and anaerobic respiration

Key words

Part 3 of 19

Key words

Words you'll need today

Producer: An organism that makes its own food by photosynthesis.
Food web: Interconnected food chains showing all the feeding relationships in a habitat.
Interdependence: Organisms relying on each other for food, pollination, shelter or seed dispersal.
Pollination: Transfer of pollen so a plant can produce seed.
Population: All the individuals of one species in a habitat.

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.

Explore the idea

Part 5 of 19

Learn

Webs, not chains

Consider oak - caterpillar - blue tit - sparrowhawk, and also oak - weevil - shrew - owl, with the shrew eaten by both owl and sparrowhawk. Arrows always point in the direction the energy travels: from the eaten to the eater. That single rule prevents most food web mistakes.

Explore the idea

Part 6 of 19

Learn

Predicting a knock-on effect

If caterpillar numbers fall, blue tit numbers fall too, and sparrowhawks may switch to shrews, so shrew numbers fall even though nothing happened to them directly. Meanwhile oak leaves suffer less damage. Answer these questions by tracing arrows step by step, and always name the reason - fewer prey, or less competition.

Quick check

Part 7 of 19

Quick check

In a food chain, arrows point...

Quick check

Part 8 of 19

Quick check

If caterpillars decline, shrews may also decline because...

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

Learning cycle

Part 10 of 19

Learning cycle 2 of 2

Pollinators and human impact

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

Explore the idea

Part 11 of 19

Learn

Insect-pollinated crops

Apples, pears, strawberries, beans, tomatoes and oilseed rape all yield far better when insects visit them. The plant provides nectar; the insect moves pollen; both benefit. Pesticide use, disease and habitat loss reduce pollinator numbers, and that is a food supply problem for us, not only a wildlife problem.

Explore the idea

Part 12 of 19

Learn

Other kinds of dependence

Interdependence is not just feeding. Birds disperse seeds, fungi break down dead material and return nutrients to the soil, and gut bacteria digest fibre. Ecosystems fail through the loss of these services as often as through the loss of a predator, which is why conservation work often targets habitat rather than a single species.

Quick check

Part 13 of 19

Quick check

Insect pollination matters to farming because...

Quick check

Part 14 of 19

Quick check

Decomposers are important because they...

Common mix-ups

Part 15 of 19

Common mix-ups

Things people often get wrong

Food web arrows show energy flow, so they point towards the eater.
Removing a predator does not simply mean 'more prey forever' - food supply limits the rise.
Not all pollination is by bees; hoverflies, beetles, moths and wind all pollinate.
Decomposers are part of the ecosystem, not an afterthought.

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

Challenge round

Part 17 of 19

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

The plant provides nectar; the ____ moves pollen; both benefit.

____ is not just feeding.

Mastery quiz

Part 18 of 19

Marked quiz

End of lesson quiz: Food webs, pollinators and interdependence

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

1. A producer is an organism that...
2. A food web shows...
3. Interdependence includes...
4. Pollinator decline is caused partly by...
5. Removing a top predator usually causes prey numbers to...
6. A population is...

Lesson round-up

Part 19 of 19

Lesson round-up

Ready when you are

Quiz score

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Games

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Points this lesson

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

Name the variable the club changed the second time, and one variable they kept the same.
Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
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

Write your answer, notes or working here

Saved as you type.

Photos of paper work, diagrams or working outHow many minutes did the written work take?

Part 1 of 19 · Watch & discover

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