Grade by Grade
B. Life Systems · Growth and Changes in Plants

Plants and Animals Depend on Each Other

B2.8 A1.1 A1.5About 35 minutes
Learning goals
  • I can describe ways animals, including people, depend on plants.
  • I can describe ways plants depend on animals, including people.
  • I can explain what could happen if one living thing disappeared.
  • I can research how one animal and one plant help each other.

Words to know

depend
To need something or someone in order to live or do well.
pollinator
An animal, like a bee, butterfly or hummingbird, that carries pollen from flower to flower.
shelter
A safe place to live, rest or hide.
food chain
A path that shows who eats whom, starting with a plant. Example: grass → rabbit → fox.
decompose
To rot and break down into tiny bits that become part of the soil.

Remember from Grade 1

In Grade 1 you learned that living things help each other meet their needs. Now we will look more closely at the many ways plants and animals (including people) depend on each other.

A busy milkweed patch

On a summer day, Priya watched a milkweed patch at the edge of a field. A monarch caterpillar was munching a leaf. A bumblebee was crawling over the pink flowers, drinking nectar. A ladybug was hunting tiny insects on the stem.

The milkweed was a restaurant and a home for these animals. And the bee was helping the milkweed by carrying its pollen. Plants and animals are connected in many ways!

A striped yellow, black and white monarch caterpillar eating a milkweed leaf beside a pink milkweed flower cluster where a bumblebee is feeding.
The caterpillar eats the milkweed leaves, and the bumblebee drinks nectar from its flowers. In return, the bee carries the milkweed's pollen. AI-generated image
PlantsAnimalsgive food, shelterand oxygencarry pollen and seeds, givenutrients and carbon dioxide
Plants and animals help each other. Plants give animals food, shelter and oxygen. Animals carry pollen and seeds and give plants nutrients and carbon dioxide.

How animals depend on plants

  • Food: Many animals eat plants. Deer eat twigs, rabbits eat clover, and bears eat berries. Even meat-eaters depend on plants, because the animals they eat ate plants. This is a food chain: clover → rabbit → fox.
  • Shelter: Birds build nests in trees and shrubs. Squirrels live in tree holes. Beavers use trees to build lodges and dams.
  • Oxygen: Plants give off the oxygen that animals breathe.
  • Special plants: Some animals depend on one kind of plant. Monarch caterpillars eat only milkweed.
the Suncloverrabbitfoxenergy moves along the arrows
A food chain: clover → rabbit → fox. Energy moves from the Sun to the clover, to the rabbit that eats the clover, to the fox that eats the rabbit. So the fox depends on plants too!

How plants depend on animals

  • Pollination: Bees, butterflies, moths and hummingbirds carry pollen from flower to flower, so plants can make seeds.
  • Spreading seeds: Blue jays and squirrels bury acorns and forget some. Bears and birds eat berries and drop the seeds far away. Burrs stick to fur.
  • Nutrients: Animal droppings, and dead animals that decompose, add nutrients to the soil.
  • Carbon dioxide: Animals breathe out carbon dioxide, which plants use for photosynthesis.

People and plants

People depend on plants for food (fruits, vegetables, grains like wheat and rice), for the oxygen we breathe, and for wood, paper, cotton clothes and some medicines.

Plants depend on people too, especially the plants we grow. Farmers and gardeners plant seeds, water and weed their crops, and protect them. People also plant trees in cities and protect wild plants in parks. But people can harm plants too (you will learn more in a later lesson).

Worked example

Let's find the connections

A black bear lives in an Ontario forest. List ways the bear depends on plants and ways plants depend on the bear.

  1. Bear needs plants: it eats berries, nuts, grasses and roots. It may make its winter den under the roots of a fallen tree.
  2. Plants need the bear: the bear eats berries and drops the seeds in its droppings, far away. The droppings add nutrients to the soil, which helps the seeds grow.

The bear gets food and shelter from plants. Berry plants get their seeds spread and some nutrients from the bear.

Worked example

Let's think about a missing link

What could happen to an apple orchard if there were far fewer bees?

  1. Bees pollinate apple flowers.
  2. Fewer bees means fewer flowers get pollinated.
  3. Fewer pollinated flowers means fewer apples grow.
  4. Fewer apples means less food for people and for animals like deer that eat fallen apples.

There would be fewer apples. When one living thing disappears, other living things are affected too.

Just for fun

Monarch caterpillars eat only milkweed leaves. Talk about a picky eater! Luckily for them, milkweed is the only menu they need.

Hands-on activity

Partners research card

You need: paper, pencil crayons, and a library book or a website a grown-up helps you choose.

  1. Choose a pair to research: monarch and milkweed, bumblebee and clover, blue jay and oak tree, hummingbird and wild columbine, or black bear and blueberries.
  2. Find out: How does the animal depend on the plant? How does the plant depend on the animal?
  3. Make a card with a drawing of both partners. Draw arrows between them and write on each arrow what they give each other.
  4. Present your card to your family. Use at least 3 science words from this unit, like pollen, seed, nutrients, shelter.

Bonus: Go outside (with a grown-up) and look for a plant with an animal on it, like a bee on a flower or a bird in a tree. What is the animal getting? What is the plant getting?

Your turn

1

Name three ways animals depend on plants.

2

Name three ways plants depend on animals.

3

What is a pollinator? Give an example.

4

Which plant do monarch caterpillars depend on?

5

Finish the food chain: grass → ? → wolf

6

How do people depend on plants? Give two ways.

7

How do people help plants?

More practice: warm-up

1

What do bees get from flowers?

2

Where do many birds build nests?

3

What gas do plants give off that animals breathe?

4

What do squirrels bury that can grow into trees?

5

What does the word "depend" mean?

More practice: on your own

1

A fox does not eat plants. Does it still depend on plants? Explain.

2

How does a blue jay help an oak tree?

3

How do animal droppings help plants?

4

A beaver cuts down poplar trees. How does the beaver depend on the trees?

5

Why are there signs asking people to plant milkweed?

Challenge

1

If all the milkweed in an area disappeared, what would happen to the monarchs there? Explain.

2

Explain how a bear eating blueberries in August could lead to a new blueberry bush.

3

Make a food chain with 3 living things from an Ontario lake. Start with a plant.

Check your understanding

Quiz

1.

Which is a way animals depend on plants?

2.

Which is a way plants depend on animals?

3.

Which animal is a pollinator?

4.

What is the right order of this food chain?

5.

What could happen if most bees disappeared from an orchard?

6.

How do people help plants?

For parents and teachers

Big idea (B2.8): Plants and animals, including humans, depend on each other: plants provide food, shelter and oxygen; animals pollinate, disperse seeds, add nutrients and release carbon dioxide; people grow and protect plants and rely on them for food, materials and medicine. The research card practises a simple research process (A1.1) and communication with vocabulary (A1.5).

Common difficulties:

  • Thinking meat-eaters do not need plants. Trace the food chain back together.
  • Seeing the relationship as one-way (animals use plants). Keep asking, "And what does the plant get?"

How to help: Watch a flower patch for five minutes and count the visitors. Plant native flowers like milkweed, wild bergamot or black-eyed Susan to feed pollinators. Bees can sting; teach your child to watch calmly from a short distance and never swat.