Year 3 Science: The stem: holding up and carrying
Part of the Year 3 Science parts of a flowering plant chapter. Chapter overview · whole chapter on one page
The stem: holding up and carrying
The stem has three main jobs:
- it holds up the leaves and flower, so that they can reach the light;
- it carries water and minerals up from the roots to the leaves and flower;
- it carries food from the leaves to the other parts of the plant, including the roots.
The stem of a tree is called its trunk. A trunk is thick and woody, which means it is hard, like wood. It holds up the branches, the leaves and the flowers.
Key ideas
- The stem holds up the leaves and flower.
- The stem carries water and minerals up from the roots.
- The stem carries food from the leaves to the other parts of the plant.
- A tree trunk is a thick, woody stem.
Method. Look at the direction of the blue arrow.
- Find the blue arrow. The blue arrow is on the left of the stem, and it is labelled water and minerals up.blue arrow
- Read its direction. The arrowhead points to the top of the stem.arrowhead at the top
- Name the direction. So the water moves up the stem, from the roots to the leaves.up
- Write the answer. up
Check. Water goes up from the roots to the leaves. ✓
Method. Think about the job of the stem, and which choice is that job.
- Read A. The stem holds the leaves up, so this is the job that has been lost.A: holding leaves up
- Read B. Making seeds is the job of the flower, not the stem.B: flower
- Choose the job. The leaves fall over because the stem can no longer hold them up.A
- Write the answer. A
Check. The stem holds up the leaves and flower. ✓
Method. Start at 0, then read the other end of the stem.
- Find the 0 mark. Measuring starts at the 0 mark, so the stem begins at 0.starts at 0
- Read the other end. The top of the stem is at the 9 cm mark.ends at 9 cm
- Write the height with the unit. A height is written in centimetres, cm.9 cm
- Write the answer. 9 cm
Check. Count along the ruler from 0 to 9, one centimetre at a time. ✓
Watch out. If you do not start at 0, the answer will be wrong.
Watch out
Watch out: the stem is not the same as the leaves. The leaves grow out from the stem, and the stem holds them up.
Try it at home or school (with a grown-up). Look at a tree in a park or garden with a grown-up. Find its trunk, and count the main branches that grow out of the trunk. Do not touch or climb the tree. Wash your hands afterwards if you have touched anything.
Exam tip
Grown-up tip. Ask: “What is holding the leaves up? Which way does the water go?” Let your child point with a finger from the roots, up the stem, to a leaf.
Exercise 2C The stem: holding up and carrying
Method. Think about what grows on the stem.
- Think about the leaves. The leaves grow out from the stem and are held up by it.leaves
- Think about the flower. The flower grows on the plant and is held up by the stem.flower
- Write the answer. leaves and flower
Check. The stem holds the leaves and flower up. ✓
Method. Think about the thick, woody stem of a tree.
- Think about the tree. A tree has one thick, woody stem.thick, woody
- Name it. The thick, woody stem of a tree is its trunk.trunk
- Write the answer. trunk
Check. A trunk is a tree’s stem. ✓
Method. Think about the part that joins the roots to the leaves.
- Think about the path of water. Water goes from the roots, up through the middle of the plant.roots to leaves
- Name the part. The part that joins the roots and leaves is the stem.stem
- Write the answer. stem
Check. The stem carries water up to the leaves. ✓
Method. Think about where plant food is made.
- Think about the food. Food is made in the leaves, using light.made in leaves
- Follow the food. The stem then carries this food to other parts, such as the roots.food carried to roots
- Write the answer. leaves
Check. The leaves make the food, and the stem carries it. ✓
Method. Think about where the leaves are held.
- Read the sentence. The stem holds the leaves up, above the soil.up
- Write the answer. up
Check. The stem lifts the leaves towards the light. ✓
Method. Think about the word that describes a tree trunk.
- Read the sentence. A trunk is thick and hard, like wood.hard like wood
- Write the answer. woody
Check. Woody means hard, like wood. ✓
Method. Look at where the blue arrow starts.
- Find the blue arrow. The blue arrow is on the left of the stem, labelled water and minerals up.blue arrow
- Find where it starts. The arrow starts at the bottom of the stem, where the roots are.bottom, by the roots
- Name the part. So the water and minerals come from the roots.roots
- Write the answer. roots
Check. The arrow starts at the roots and points up to the leaves. ✓
Method. Start at 0 and read the other end.
- Find the 0 mark. The stem starts at 0.starts at 0
- Read the other end. The top of the stem is at the 6 cm mark.ends at 6 cm
- Write the answer. 6 cm
Check. Count 6 centimetres along the ruler. ✓
Method. Find the height in week 2 and the height in week 3, then take the smaller away from the bigger.
- Read the two heights. The stem was 32 cm in week 2 and 40 cm in week 3.32 and 40
- Take the smaller away from the bigger. The growth is how much taller the stem got.40 − 32 = 8
- Write the answer. 8 cm
Check. 32 + 8 = 40, so the answer is right. ✓
Watch out. Growth is the change in height. Use the week 2 height, not the week 1 height.
Method. Think about what the measurement is.
- Think about the measurement. The stem is a length, so we measure it in centimetres.a length
- Choose the unit. Kilograms measure mass, so cm is the right unit.cm
- Write the answer. cm
Check. A height is a length, so the unit is cm. ✓
Method. Think about where the food is made.
- Think about the food. Food is made in the leaves, not in the roots.made in leaves
- Decide. So the stem carries food from the leaves to the rest of the plant. The statement is false.from the leaves
- Write the answer. no
Check. The stem carries food from the leaves to the rest of the plant. ✓
Method. Think about the path of the water.
- Think about the path. Water goes from the roots, up the stem, to the leaves.roots to leaves
- Give the reason. A broken stem cannot carry the water up, so the leaves may not get it.broken, cannot carry
- Write the answer. Accept any sentence that says a broken stem cannot carry water up from the roots to the leaves.
Check. The stem is the path for water up the plant. ✓