Practice Questions
1.State what a vascular bundle contains
Xylem and Phloem
2. Describe 3 adaptations of xylem
Any 3 of the following
| Structural part of Xylem | Adaptation |
|---|---|
| Hollow tubes (no end walls / no cytoplasm) | Allows water to flow freely from root to leaf. |
| Lignin in cell walls | Strengthens the tubes and prevents them collapsing under pressure. Helps waterproof the vessels. |
| Thick walls | Give support to the plant, helping keep it upright. |
| One-way flow | Water and minerals move upwards only — from roots to leaves. |
3. Describe 3 adaptations of phloem
Any 3 of the following
| Structural part of Phloem | Adaptation |
|---|---|
| Sieve tube elements | Long cells joined end to end to form tubes for transport. Have sieve plates (holes at ends) that allow sugars to flow. |
| Companion cells | Each sieve tube has a companion cell beside it. Contain lots of mitochondria to provide energy for active transport of sugars. |
| Cells are alive | Unlike xylem, phloem vessels are living cells, necessary for active transport. |
| Bidirectional flow | Sugars can move up or down the plant to where they are needed (e.g. growing regions or storage organs). |