Question

Choose the odd one out.

• A. Cortex, pericycle, pith
• B. Trichomes, stomata, cuticle
• C. Root hair, guard cells, subsidiary cells
• D. Sieve tubes, vessel elements, root hairs

Answer 1

The correct option is D Sieve tubes, vessel elements, root hairs

Here, the pattern that is seen in each set is the members of a single tissue system. In plants, the tissues come together to form the tissue system. There are three tissue systems - epidermal tissue system, ground tissue system and vascular tissue system.

Epidermal tissue system forms the outermost covering of the whole plant body. It comprises epidermal cells, stomata and epidermal appendages. Epidermal appendages include root hair and trichomes.

Ground tissue system includes all the tissues except epidermis and vascular bundles. It is made up of simple tissues such as parenchyma, collenchyma and sclerenchyma. It is found in the cortex, pith, medullary rays and pith in stems and roots.

Pericycle is a thin layer of plant tissue between the layer below the epidermis and the phloem.
Cortex is a tissue of unspecialized cells lying between the epidermis (surface cells) and the vascular tissues. Pith is composed of undifferentiated parenchyma cells which function in storage of nutrients. It is found in young plants.

Vascular tissue system consists of complex tissues such as xylem and phloem. Xylem is made up of tracheids, vessel elements, xylem parenchyma and xylem fibres. Phloem is made up of sieve tube elements, companion cells, phloem fibres and phloem parenchyma.