Botany and Plant Science

Hygroscopic roots occur means water absorbing roots from the atmosphere. Hygroscopic roots occur in Vanda because it is an epiphyte which absorbs moisture from the atmosphere as its source of water.

Regions of root from base to root tip are maturation zone , elongation zone and cell division zone and root cap because the meristematic tissue is present at the tip of the root above the root cap which grows downwards as the upper layers mature into permanent structures.

Origin of lateral roots is endogenous in origin because for absorption of water and minerals the roots should contain vascular structures which are in the deeper layers.

The main root of tap root system represents radicle because, in a seed, radicle is the part which is destined to produce where it grows and it produces branches from the main root.

A. Wolffia is a free-floating thallus, so its body does not contain roots.

Root hair the large thread like structure arises from the epidermis layer of the root. These basically arise from the region of elongation. Root hairs are rarely branched. These are exogenous in origin because arise from the superficial layer of the epidermis. Root hairs are unicellular.

Thus, the correct answer is 'False.'

They persist until the epidermis separates from the root, although hairs composed of living cells are usually found only on the tip 1 cm. of the roots. Hairs of adventitious roots growing in the soil are most commonly or always unicellular and look very much the same as hairs of many other roots.

Primary roots continue to grow to form a secondary root system as the secondary root system is large and extends deep into the ground.

Respiratory roots are non-photosynthetic and non-green in nature. They are seen in plants growing in marshy regions and in aquatic plants. They are found in wheat. They are also called as breathing roots. Fasciculated roots are modified adventitious roots. They are arranged in fascicles.

Some roots, called adventitious roots, arise from an organ other than the root—usually a stem, sometimes a leaf. They are especially numerous on underground stems, such as rhizomes, corms, and tubers, and make it possible to vegetatively propagate many plants from stem or leaf cuttings.

Root hairs are unicellular extensions of epidermal cells found in the zone of maturation, where they are responsible for water and mineral absorption.

Roots exhibit negative phototropism, meaning they grow away from the light source, while stems exhibit positive phototropism.

The quiescent centre (QC) is a small group of cells with low mitotic activity (they divide sometimes, but only rarely). QC's are to be found at the tips of growing roots, in the root meristem, and are typically surrounded by groups of initial cells. Through rounds of cell division, these initial cells give rise to the various tissues of the root and so there are usually vascular initials, pericycle initials, cortex initials etc. It is thought that the QC sends out signals to these initial cells to ensure that they remain in an initial state and keep dividing to produce whatever tissue they are responsible for. So, root apex has a zone of slow dividing cells in the middle of rapidly dividing cells which is called as quiescent centre. 

Root xylem is exarch xylem in which xylem formed first is present towards the periphery and is termed as protoxylem while metaxylem is present near the centre. Exarch xylem refers to the presence of protoxylem and metaxylem in different radii, not in same.