Gymnosperm wood is non-porous because it
(a) lacks vessels
(b) contains tracheae
(c) has abundant fibres
(d) contains no fibres.

Options

A. lacks vessels
B. contains tracheae
C. has abundant fibres
D. contains no fibres.

Answer

To solve the question "Gymnosperm wood is non-porous because it:", we need to analyze the options provided and understand the characteristics of gymnosperm wood.

### Step-by-Step Solution:

1. **Understand Gymnosperms**: Gymnosperms are a group of seed-producing plants that include conifers, cycads, Ginkgo, and gnetophytes. They are known for their wood characteristics.

2. **Identify Wood Composition**: The wood of gymnosperms is primarily composed of tracheids, which are long, narrow cells that help in water conduction and provide structural support. Unlike angiosperms, gymnosperms do not have vessels in their wood.

3. **Evaluate the Options**:
- **(a) Lacks vessels**: This option suggests that gymnosperm wood does not contain vessels, which is true. The absence of vessels contributes to the non-porous nature of the wood.
- **(b) Contains tracheae**: This option is misleading. While gymnosperms do contain tracheids (not tracheae), the presence of tracheids does not make the wood porous.
- **(c) Has abundant fibres**: While gymnosperms may have fibers, this does not directly relate to the non-porous nature of the wood.
- **(d) Contains no fibres**: This is incorrect as gymnosperms do have fibers, but their presence does not affect the porosity of the wood.

4. **Conclusion**: The correct answer is (a) lacks vessels. The absence of vessels in gymnosperm wood is the primary reason it is classified as non-porous.

### Final Answer:
Gymnosperm wood is non-porous because it **lacks vessels** (Option a).

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