What important role does lignin play in vascular plants? a. It is the major component of the cuticle, which prevents plants from drying out. b. It forms the outer layer of pollen grains. c. It forms the tough, rigid cell walls of water-conducting cells. d. It nourishes the embryo in seed plants.

Verified step by step guidance

1. Step 1: Understand the question. The question is asking about the role of lignin in vascular plants. Lignin is a complex organic polymer that is important for the structural integrity of certain plant tissues.
2. Step 2: Evaluate each of the given options. Option a suggests that lignin is the major component of the cuticle, which prevents plants from drying out. This is incorrect because the cuticle is primarily composed of waxes and cutin, not lignin.
3. Step 3: Consider option b, which suggests that lignin forms the outer layer of pollen grains. This is also incorrect. The outer layer of pollen grains is formed by a substance called sporopollenin.
4. Step 4: Look at option c, which suggests that lignin forms the tough, rigid cell walls of water-conducting cells. This is correct. Lignin is a key component of the secondary cell walls of plant cells, particularly in xylem tissue, which conducts water and minerals in vascular plants.
5. Step 5: Finally, consider option d, which suggests that lignin nourishes the embryo in seed plants. This is incorrect. The embryo in seed plants is nourished by the endosperm, not lignin.

Key Concepts

Lignin

Lignin is a complex organic polymer found in the cell walls of vascular plants. It provides structural support and rigidity, allowing plants to grow tall and withstand various environmental stresses. Lignin is particularly abundant in woody plants, where it contributes to the strength of the xylem, the tissue responsible for water transport.

Vascular Plants

Vascular plants are a group of plants that have specialized tissues, namely xylem and phloem, for the transport of water, nutrients, and food. This adaptation allows them to thrive in a variety of environments and grow larger than non-vascular plants. The presence of lignin in their cell walls is crucial for maintaining the integrity and functionality of these vascular tissues.

Cell Walls

Cell walls are rigid outer layers that provide structural support and protection to plant cells. In vascular plants, the cell walls of xylem cells are reinforced with lignin, making them tough and resistant to collapse under pressure. This rigidity is essential for the efficient transport of water and minerals from the roots to the leaves, enabling the plant to maintain its upright structure.