Question

Select the incorrect matching: (a) Protophloem Narrow sieve tubes (b) Metaphloem Bigger sieve tubes (c) Gymnosperm Albuminous cells and sieve cells (d) Gymnosperm Vessels in xylem

Short answer

The incorrect matching is (d) Gymnosperm - Vessels in xylem.

Step-by-step solution

Review and Compare Definitions

Retrieve the definitions and characteristics of protophloem, metaphloem, gymnosperm, and vessels. Protophloem should have narrow sieve tubes, metaphloem should contain larger sieve tubes, gymnosperms generally house albuminous cells and sieve cells, and gymnosperms should also have vessels in their xylem.

Assess Each Matching Pair

Given the definitions and descriptions identified in Step 1, evaluate each matching pair to validate the correctness. Testing each proposition, we'll notice that (a), (b) and (c) are correct matches.

Identify the Incorrect Matching

By process of elimination, the incorrect match is (d) Gymnosperm - Vessels in xylem. Indeed, gymnosperms do not have vessels in their xylem - this is a characteristic of angiosperms.

Key concepts

Protophloem

Protophloem is a component of phloem tissue in plants, and it plays a crucial role in transporting nutrients. As plants develop, phloem is differentiated into protophloem and metaphloem. Protophloem is characterized by having narrow sieve tubes, which are among the first conducting cells in young stems and leaves during the early growth stages.
These sieve tubes allow the movement of organic solutes, primarily sugars, from photosynthetic tissues to various parts of the plant.
However, since the narrow sieve tubes of protophloem quickly become nonfunctional due to the stretching of plant tissues, they are replaced by metaphloem in mature regions of the plant. This replacement ensures the plant continues to efficiently transport nutrients as it grows.

Metaphloem

Metaphloem is the second stage of phloem development, following the protophloem. In contrast to the protophloem, metaphloem features larger sieve tubes, which enable more efficient transport of substances throughout the plant.
These larger sieve tubes are better suited to the mature regions of a plant, where they effectively facilitate the long-distance transport of nutrients.
The enhanced diameter of metaphloem sieve tubes ensures that plants can sustain extensive growth and development. Besides the transportation of nutrients, metaphloem also supports the plant's structure to some degree, by accommodating the increasing demands as the plant matures.

Gymnosperms

Gymnosperms are a group of seed-producing plants that include conifers. Unlike angiosperms, gymnosperms do not produce flowers or fruit. Their seeds are usually exposed, not enclosed in a fruit.
Gymnosperms contain albuminous cells and sieve cells, which are integral to their phloem tissues. These cells aid in the transport of nutrients throughout the plant.
One key aspect that differentiates gymnosperms from angiosperms is that they do not have vessels in their xylem. Instead, their xylem is composed primarily of tracheids, which, although less efficient than vessels, perform the function of conducting water and minerals from roots to other plant parts.

Xylem

Xylem is a vital vascular tissue in plants responsible for water and mineral transport from roots to stems and leaves. It, along with phloem, forms the vascular bundle that sustains plant growth and development.
One might wonder why gymnosperms do not possess vessels in their xylem. Instead of vessels, gymnosperms have tracheids, which are elongated cells that help in the conduction and support of the plant.
Tracheids allow water movement through pits, and even though they may not be as efficient as vessels found in angiosperms, they provide structural strength and resistance to air embolism, maintaining the plant's integrity even under adverse conditions.