Question

Assertion: Xylem is complex tissue Reason: Xylem is made up of more than one type of cells

Short answer

The Assertion: 'Xylem is complex tissue' is correct. The Reason: 'Xylem is made up of more than one type of cells' is a valid reason supporting the assertion. Thus, both the assertion and the reason are correct and the reason accurately explains the assertion.

Step-by-step solution

The Definition of Xylem

Xylem is a type of tissue in vascular plants that transports water and some nutrients from the roots to the rest of the plant. It is one of the two types of transport tissue; the other type is phloem, which transports food from photosynthesis from leaves to the rest of the plant.

Composition of Xylem

Xylem is indeed a complex tissue because it is composed of more than one type of cell. These types of cells include tracheids, vessel elements, xylem fibers and xylem parenchyma. All these cells are put together in various ways to constitute comprehensive tissue, justifying the term 'complex tissue'.

Correlation of Assertion and Reason

After understanding the definition and composition of xylem, it is clear that the given reason 'Xylem is made up of more than one type of cells' is a correct explanation for the assertion 'Xylem is complex tissue'. The reason thoroughly explains the composition of xylem, which in turn, supports the assertion.

Key concepts

Vascular plant tissue

Plants have their own way of transporting nutrients and water, analogous to our cardiovascular system, known as vascular plant tissue. This system comprises two primary components: xylem and phloem. The xylem's main role is to ferry water and vital minerals from the roots to the rest of the plant.

Xylem's function in plants can be likened to pipes that carry water in a building, ensuring it reaches all parts necessary for a plant's survival. This transportation system is critical for the support and longevity of plants, especially in tall trees. Without a functioning vascular tissue system, essential fluids wouldn’t reach the leaves for photosynthesis or to other growing regions, impacting the plant's development and overall health.

Transportation of water in plants

The process of water transportation in plants is fascinating and complex. Evaporation of water from the leaves in a process known as transpiration creates a negative pressure gradient that helps draw water upward through the xylem channels. Imagine sipping a drink with a straw – transpiration is like the sucking action creating an upward pull.

This cohesive water journey from root to leaf depends on a well-orchestrated system that includes both active and passive transport. Roots actively take up minerals and water from the soil, while the cohesive nature of water molecules and their adhesion to the xylem walls facilitate this process passively. It’s a seamless and elegant system critical to the health and growth of vascular plants.

Xylem cell types

Xylem is composed of several cell types, each with a unique function, accounting for its categorization as a complex tissue. Among these cells are:

• Tracheids: Long, thin cells that help transport water and give structural support. Their tapered ends overlap with each other, creating a continuous network of water-conducting channels.
• Vessel elements: These are wider and shorter than tracheids, and they align end-to-end to form long tubes known as vessels that efficiently transport water throughout the plant.
• Xylem fibers: Providing additional support, these fibers are more about structural integrity than water transport.
• Xylem parenchyma: The least specialized, these cells serve as storage for the xylem and can also aid in the transport of water and nutrients.

Each of these cells plays a pivotal part in the plant's wellbeing, akin to the various roles different cell types play in animal tissues.