Question

A root endodermis is a. an innermost layer of cortex cells that display characteristic Casparian strips. b. a layer of cells just inside the epidermis of a root. c. a layer of cells just outside the epidermis of a root. d. a group of specialized cells that occur within the root epidermis. e. none of the above.

Short answer

The root endodermis is an innermost layer of cortex cells that display characteristic Casparian strips.

Step-by-step solution

Analyze choices

Consider the options provided: a) innermost layer of cortex cells with characteristic Casparian strips, b) layer of cells just inside the root epidermis, c) layer of cells just outside the root epidermis, d) group of specialized cells within the root epidermis, e) none of the above.

Apply knowledge

Recall that the root endodermis is a single cell layer that surrounds the vascular tissue in roots. It refers to a layer of cells that blocks the transport of ions and substances from the soil into the xylem, through its Casparian strip.

Find best choice

Compare the provided options with the knowledge about endodermis. The best choice would be an innermost layer of cortex cells that display characteristic Casparian strips.

Key concepts

Casparian strips

Casparian strips are unique features found in the cell walls of the root endodermis, the innermost layer of cortex cells. These strips play a crucial role in regulating the flow of water and nutrients into the plant's vascular system. Composed of a waxy material called suberin, Casparian strips form waterproof barriers.
They help in controlling the movement of substances between the soil and the plant's xylem and phloem. This property makes it possible for the plant to selectively absorb essential ions and nutrients while keeping out potential toxins.

• Located only in endodermis
• Prevent backflow of water and solutes
• Aid in root pressure

By acting as a selective barrier, Casparian strips ensure that harmful substances do not travel unchecked into the plant's transport system, protecting the plant's internal environments.

cortex cells

Cortex cells are a significant component of the plant root's structure, surrounding the root's vascular tissue and directly linked to nutrient and water uptake. These cells serve as a storage area for carbohydrates and other substances crucial for the plant's growth and health. Located between the epidermis and the endodermis, they play a conduit role.
Cortex cells also facilitate the transport of nutrients to the inner layers of the root, particularly towards the vascular tissue.

• Primarily involved in storage
• Support structure of the root
• Help in lateral movement of substances

This layer of cells aids in the plant's ability to withstand various stresses by acting as a buffer and participating in repairing damaged tissues. Overall, cortex cells are essential in maintaining the plant’s vitality by supporting both structural and nutritional needs.

vascular tissue in roots

Vascular tissue in roots comprises two main components: xylem and phloem. These tissues form the transport system of the plant, crucial for moving water, nutrients, and sugars throughout the plant body. Xylem is responsible for transporting water and dissolved minerals from the soil upwards, while phloem distributes the sugars produced through photosynthesis.

• Xylem: conducts water and minerals
• Phloem: transports organic nutrients
• Located centrally within the root

The arrangement of these tissues in the root forms a central stele, generally surrounded by the endodermis, which is bordered by cortex cells. This setup helps in the efficient distribution of essential resources to all parts of the plant and allows for growth and development in varying environments. Without vascular tissue, plants would not have the means to efficiently transport vital resources, impacting their ability to survive and thrive.