KS3 · Biology

Plant adaptations to environment

A cactus has spines instead of leaves, and one plant dissolves flies. Every plant feature answers a problem, so what's the problem?

Sort the features

Which job does each feature do?

An adaptation is a feature that helps an organism survive and reproduce where it lives. For each plant feature, tick every job it helps with. Some features do two jobs. Some do none of these three.

  • A Helps photosynthesis
  • B Helps get or keep water
  • C Protects from being eaten
  1. Broad leaves
  2. Very thin leaves
  3. Chlorophyll in the leaves
  4. Thorns on a thistle or blackberry
  5. Very long cactus roots
  6. Shallow cactus roots
  7. Cactus spines
  8. A cactus's swollen green stem
  9. A Venus flytrap's trap
  10. Flowers
  11. Fruit

Think it through

Would a cactus do better with broad leaves?

Broad leaves are a real adaptation: they absorb more light for photosynthesis. A friend looks at a cactus in a sunny desert and says it should grow some.

Which idea is closest to what you think?
How sure are you?

Predict, then check

You've seen the trap in the sorting activity. Now work out its job.

A Venus flytrap snaps shut when a fly lands in it. Why does it do that?

What flowers and fruit are for

Step through one route a plant's next generation can take.

  1. Flowers attract pollinatorsSome plants have flowers that help attract pollinators, so that the plant can reproduce.
  2. The plant makes fruit or nutsOnce it has reproduced, the plant makes fruit or nuts with its seeds inside. The fruit helps it disperse, which means spread, its seeds.
  3. Animals eat the fruitMany plants produce nuts or fruit containing seeds, and animals eat them.
  4. Seeds are dropped far from the parentWhen the animals defecate, the seeds are deposited on the ground, away from the parent plant.
  5. A new plant growsThe seeds are now away from the parent, so a new plant can grow there.
  6. The best fruit wins more dispersersPlants that produce the most or best fruits and nuts are more likely to attract seed-dispersing animals. That increases their likelihood of having offspring.
  7. Or the wind does the jobA dandelion's seeds are scattered by the wind instead of by animals, so its new plants also grow far away from the parent plant.

Competition between plants

?

Reason it through

Why does being well adapted matter so much for a plant?

Link 1 of 4

First link · your turn

Plants growing close together are in the same patch. What do they end up competing for?

2
Locked — reveal the link above first
3
Locked — reveal the link above first
4
Locked — reveal the link above first

Have a go

Describe a cactus

Describe how a cactus is adapted to living in the desert. Aim for four different points, and say what each feature does. [4 marks]

0 words · your answer stays on this page and is not sent anywhere.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

What you need to know

  • An adaptation is a feature that helps an organism survive and reproduce in its own environment.
  • Adaptations are specific to the environment. Move the organism somewhere else and they don't work.
  • Plants make their food, glucose, by photosynthesis. Many of their adaptations help them do as much of it as they can.
  • Chlorophyll in the leaves absorbs sunlight. That gives the energy for photosynthesis.
  • Broad leaves absorb more light. Very thin leaves help gas exchange: carbon dioxide gets in, oxygen gets out.
  • Have a goPredict: a plant grows lots more leaves. Does photosynthesis get easier, harder or stay the same?

    Easier.

    More leaves, or bigger ones, mean more surface to absorb sunlight, so more photosynthesis and more glucose.

  • Thorns, like a thistle's or a blackberry's, deter herbivores from eating the plant.
  • Cacti live in dry places. Their leaves are reduced to spines, which reduce water loss and protect them.
  • A cactus's swollen stem stores water. Photosynthesis happens in the green stem, not in leaves.
  • Cacti have some really long roots for deep water, and some shallow roots to collect dew.
  • Flowers attract pollinators so plants can reproduce. Fruit helps them disperse their seeds.
  • Have a goPick one: which does a flower attract, and which does a fruit attract: pollinators or seed-dispersing animals?

    Flowers attract pollinators. Fruit attracts seed-dispersing animals.

    Flowers help the plant reproduce. Fruit helps spread the seeds, so the two jobs happen at different stages.

  • The Venus flytrap lives in nutrient-poor soil. It dissolves flies to get essential nitrogen.
  • Plants compete for light, water, minerals, space, pollinators and seed dispersers. Adaptations give an advantage.
  • Have a goName two things plants growing close together might compete for that aren't light.

    Any two of: water, minerals, space, pollinators, seed dispersers.

    Light is only one resource. Roots also need space, and that space decides how much water and minerals they can reach.

  • The best adapted organisms are the fittest. They're more likely to compete successfully, survive and reproduce.

The big picture

Plants have features that help them survive and reproduce where they live: for photosynthesis, for getting and keeping water, for avoiding being eaten, and for spreading their seeds. Each feature suits its own environment, and well-adapted plants win the competition for light, water, minerals and space.

Key points

1An adaptation helps an organism survive and reproduce in its environment, and it is specific to that environment.
2Plant features do different jobs: photosynthesis, getting or keeping water, protection, reproduction and spreading seeds, and getting nutrients.
3Some features do two jobs at once, like cactus spines and the cactus's green stem.
4Plants compete for light, water, minerals, space, pollinators and seed dispersers.
5The best-adapted plants are the fittest, so they're more likely to survive and reproduce.

Worked example

Problem

The giant water lily has leaves with a very large surface area. Explain how that is an adaptation.

⚠ Watch out

Naming a feature without saying what it does. 'Cacti have roots' tells us nothing. 'Cacti have long roots that reach water deep underground' names the job.

🧠

Memory hook

Feature, job, place. For any feature ask: what problem does it solve, and would it still help somewhere else?

✓

Check yourself

Pick any plant feature from this lesson. Say what problem it solves, then explain why it wouldn't give an advantage everywhere.

Flashcards

(14)
What is an adaptation?
A feature that helps an organism survive and reproduce in its particular environment.
Why can an adaptation stop working?
Adaptations are specific to the environment. If the organism is moved to a different environment, they do not work.
What does chlorophyll do?
It absorbs sunlight, which provides the energy for photosynthesis.
What are broad leaves for?
Absorbing more light for photosynthesis, so the plant can make more glucose.
What do very thin leaves help with?
Gas exchange: carbon dioxide can get into the plant and oxygen can get out.
What do thorns do?
They deter herbivores from eating the plant, for example on a thistle or a blackberry plant.
What two jobs do cactus spines do?
The leaves are reduced to spines. They reduce water loss and protect the cactus from being eaten.
Where does a cactus store water, and where does it photosynthesise?
It stores water in its swollen stem, and photosynthesis takes place in the green stem.
Why do cacti have both long and shallow roots?
Long roots get water from deep underground. Shallow roots get water from dew.
Why does a Venus flytrap trap flies?
Its soil is nutrient-poor. It dissolves the fly to get essential nitrogen.
How does fruit help a plant spread its seeds?
Animals eat fruit or nuts, and later deposit the seeds on the ground away from the parent plant.
How does a dandelion spread its seeds?
The wind scatters them, so the new plants grow far from the parent plant.
What do plants compete for?
Light, water and minerals, space, pollinators and seed dispersers.
What does 'fittest' mean?
The organisms best adapted to their environment. They are more likely to compete successfully, survive and reproduce.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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