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SavannahYear 8
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ScienceEcosystems and variation30 min★★★ difficulty

Variation within and between species

No two snow leopards are identical, and that matters: variation is the raw material that lets a species cope when its environment changes.

Part of your national curriculum
  • Biology: genetics and evolution: Understand differences between species and the variation between individuals of the same species

Lesson overview

What you'll learn in this lesson

Understand differences between species and the variation between individuals of the same species

Key learning points

  • • Between species and within a species
  • • Continuous and discontinuous
  • • Genes, environment or both
  • • Variation and survival

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

differencesspeciesvariationindividualswithin

Scroll down — the lesson carries on below

Part 1 of 19 · Discover5%
1

Watch & discover

Part 1 of 19

Watch first

Variation within and between species

Genes and environment both shape how different living things are.

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 differences between species and the variation between individuals of the same species

2

What you already know

Part 2 of 19

Before we start

What you already know

You should know that offspring resemble their parents but are not identical to them.

Recap: Food webs, pollinators and interdependence
3

Key words

Part 3 of 19

Key words

Words you'll need today

Species
A group of organisms that can breed together to produce fertile offspring.
Continuous variation
A characteristic with a range of values, such as height.
Discontinuous variation
A characteristic with distinct categories, such as blood group.
Inherited
Caused by genes passed from parents.
Environmental variation
Differences caused by surroundings, such as diet or scarring.
4

Learning cycle

Part 4 of 19

Learning cycle 1 of 2

Types of variation

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

5

Explore the idea

Part 5 of 19

Learn

Between species and within a species

Between species, differences are large and organisms cannot produce fertile offspring together. Within a species, individuals differ in many characteristics but can still interbreed. Both kinds of difference are variation, and a good answer says which kind it is talking about.

6

Explore the idea

Part 6 of 19

Learn

Continuous and discontinuous

Height, mass and fur length vary continuously: any value in a range is possible, and a histogram of a population usually shows a peak in the middle. Blood group and the presence of markings vary discontinuously: distinct categories, best shown on a bar chart. Choosing the right graph is a marked skill, not a decoration.

7

Quick check

Part 7 of 19

Quick check

Members of the same species can...

8

Quick check

Part 8 of 19

Quick check

Which is continuous variation?

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

Why variation matters

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

11

Explore the idea

Part 11 of 19

Learn

Genes, environment or both

Eye colour is inherited. A scar is environmental. Mass and height are both: genes set a range and diet and exercise determine where in it you land. Ask 'could this change without changing the genes?' - if yes, environment is involved.

12

Explore the idea

Part 12 of 19

Learn

Variation and survival

If every individual were identical, one new disease or a shifted climate could remove the whole species. Variation means some individuals may already suit the new conditions, survive and reproduce. This is why small, isolated populations - a few dozen animals in one valley - are so vulnerable, and why breeding programmes work hard to keep variation high.

13

Quick check

Part 13 of 19

Quick check

A scar is an example of variation that is...

14

Quick check

Part 14 of 19

Quick check

Low variation makes a species vulnerable because...

15

Common mix-ups

Part 15 of 19

Common mix-ups

Things people often get wrong

  • Variation is not only inherited - environment causes a great deal of it.
  • Continuous data belongs on a histogram or line graph, not a bar chart of categories.
  • Two organisms looking similar does not make them the same species.
  • Individuals do not adapt during their lives; populations change across generations.
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.

Between species, ____ are large and organisms cannot produce fertile offspring together.

Within a ____, individuals differ in many characteristics but can still interbreed.

Both kinds of difference are ____, and a good answer says which kind it is talking about.

18

Mastery quiz

Part 18 of 19

Marked quiz

End of lesson quiz: Variation within and between species

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

  1. 1. Discontinuous variation is shown best on a...

  2. 2. Height in humans is affected by...

  3. 3. Variation within a species arises from...

  4. 4. A small isolated population is at risk mainly because of...

  5. 5. Two species by definition cannot...

  6. 6. Which statement is correct?

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

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    Understand differences between species and the variation between individuals of the same species

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