P4 Science - Plant System
Created by Miss Clarissa Ng | www.clartutors.com
Parts of a Plant
Plants have different parts that work together to help the plant stay alive:
| Part | Main Function |
|---|---|
| Leaves | Trap light to make food by photosynthesis; exchange gases through stomata |
| Stem | Holds the plant upright; contains tubes that carry food, water, and mineral salts |
| Roots | Anchors the plant firmly to the ground; absorbs water and mineral salts from soil |
| Flowers | Reproductive part of the plant — produces seeds |
| Fruit | Protects and disperses seeds |
Parts of a Leaf
Leaf Blade
- The flat, broad portion of the leaf.
- Contains chlorophyll and tiny openings called stomata.
Stomata
- Tiny openings mostly found on the underside of a leaf.
- Allow the exchange of gases (carbon dioxide and oxygen) between the plant and the surroundings.
Leaf Stalk
- The leaf veins branch out from the leaf stalk.
- Contains tubes that transport water from the stem to the leaf and food from the leaf to the stem.
Leaf Veins
- Distribute substances throughout the leaf.
- Provide shape and support for the leaf.
Leaf Edge
- The outline of the leaf.
Characteristics of a Leaf
Leaves of different plants differ in their shape, edges, vein patterns, colour, and texture.
| Characteristic | Variations |
|---|---|
| Shape | Heart-shaped, oval-shaped, palm-shaped, lance-shaped |
| Edge | Smooth, jagged, lobed, wavy |
| Vein Pattern | Net vein pattern or parallel vein pattern |
| Colour | Mostly green; some are red or purple |
| Texture | Waxy, hairy, smooth |
Functions of a Leaf
Photosynthesis
- The leaves trap light to make food for the plant by photosynthesis.
- Photosynthesis is the process by which green plants make food (sugar) from carbon dioxide and water, in the presence of light and chlorophyll, releasing oxygen in the process.
Gaseous Exchange
- The leaves allow the exchange of gases between the plant and the surroundings through the stomata.
- Respiration (all times): Leaves take in oxygen and give out carbon dioxide.
- Photosynthesis (when light is present): Leaves take in carbon dioxide and give out oxygen.
Stem
| Function | Details |
|---|---|
| Holds the plant upright | Elevates the leaves so they can trap enough light for photosynthesis. Some plants (e.g., morning glory, money plant) have weak stems that grow around a pole or other plants for support. |
| Contains water-carrying tubes (xylem) | Carries water and mineral salts from the roots to all parts of the plant. |
| Contains food-carrying tubes (phloem) | Carries food from the leaves to all parts of the plant. |
Roots
| Function | Details |
|---|---|
| Anchors the plant firmly to the ground | Prevents the plant from falling over easily in the presence of wind. |
| Absorbs water and mineral salts from soil | Water is needed by leaves to make food by photosynthesis. Mineral salts are required by the plant to stay healthy. |
Summary — Functions of Plant Parts
| Plant Part | Functions |
|---|---|
| Leaves | Trap light to make food by photosynthesis. Exchange gases through stomata. |
| Stem | Holds the plant upright. Contains tubes that carry food, water, and mineral salts to different parts of the plant. |
| Roots | Anchors the plant firmly to the ground. Absorbs water and mineral salts from the soil. Stores excess food made by the leaves. |