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SavannahYear 8
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ScienceAnimals in ecosystems30 min★★★ difficulty

Human impact: pollution, plastics and accumulation

Some pollutants become more dangerous the further up a food chain you look. That single idea explains why top predators are often the worst affected.

Lesson overview

What you'll learn in this lesson

Understand how organisms affect, and are affected by, their environment, including the accumulation of toxic materials

Key learning points

  • • Persistent means it stays
  • • Concentration climbs the chain
  • • Animals change environments too
  • • Measuring with indicator species

This lesson at a glance

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

Words to know

organismsaffectaffectedenvironmentaccumulation

Scroll down — the lesson carries on below

Part 1 of 18 · Discover6%
1

Watch & discover

Part 1 of 18

Watch first

Human impact: pollution, plastics and accumulation

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

In a nutshell

Understand how organisms affect, and are affected by, their environment, including the accumulation of toxic materials

2

What you already know

Part 2 of 18

Before we start

What you already know

You should already know how food chains transfer energy, and that pollutants can enter water and air.

3

Key words

Part 3 of 18

Key words

Words you'll need today

Bioaccumulation
Build-up of a substance inside one organism over time.
Biomagnification
Increasing concentration of a substance at each level of a food chain.
Persistent
Not broken down easily in the environment or the body.
Microplastic
Plastic fragment smaller than five millimetres.
Indicator species
A species whose presence or absence signals environmental quality.
4

Learning cycle

Part 4 of 18

Learning cycle 1 of 2

How pollutants concentrate

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

5

Explore the idea

Part 5 of 18

Learn

Persistent means it stays

Some substances are not broken down by decomposers or by the body — certain pesticides, mercury compounds, and plastics. Because they are stored rather than removed, an organism's total load rises through its life. That is bioaccumulation.

6

Explore the idea

Part 6 of 18

Learn

Concentration climbs the chain

A predator eats many prey animals, absorbing the pollutant from every one. Concentration therefore rises at each level. Orcas, polar bears and birds of prey carry far higher concentrations than the small fish or insects at the bottom, which is biomagnification.

7

Quick check

Part 7 of 18

Quick check

Bioaccumulation is the build-up of a substance

8

Reset break

Part 8 of 18

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
9

Quick check

Part 9 of 18

Quick check

Why do top predators carry the highest concentrations?

10

Learning cycle

Part 10 of 18

Learning cycle 2 of 2

Measuring and reducing harm

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

11

Explore the idea

Part 11 of 18

Learn

Animals change environments too

Impact is not one-way. Beavers dam streams and create wetlands, elephants push over trees and maintain grassland, and earthworms build soil. Introduced species can change an ecosystem drastically, as rats and cats have done to island seabirds.

12

Explore the idea

Part 12 of 18

Learn

Measuring with indicator species

Lichens are sensitive to air pollution, and mayfly larvae to river pollution, so surveying them measures conditions cheaply and repeatedly. Interventions that work follow the evidence: banning specific persistent pesticides has allowed some bird of prey populations to recover.

13

Quick check

Part 13 of 18

Quick check

Which substance is most likely to biomagnify?

14

Quick check

Part 14 of 18

Quick check

Mayfly larvae are used as

15

Common mix-ups

Part 15 of 18

Common mix-ups

Things people often get wrong

  • Biomagnification is not the pollutant becoming stronger; the concentration in tissue rises.
  • Not all pollution dilutes away — persistent substances stay in bodies and sediment.
  • Animals change their environments as well as being changed by them.
16

Challenge round

Part 16 of 18

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

Mastery quiz

Part 17 of 18

Marked quiz

End of lesson quiz: Human impact: pollution, plastics and accumulation

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

  1. 1. Microplastics are smaller than

  2. 2. Beavers affect ecosystems by

  3. 3. Lichens indicate

  4. 4. Introduced rats harm island seabirds mainly by

  5. 5. Bird of prey recoveries followed

  6. 6. Persistent pollutants are hard to remove because they

18

Lesson round-up

Part 18 of 18

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 18 · Watch & discover

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