Free Kingdom Plantae MCQs with Answers

161. The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is:

• A. Elongating
• B. Widening
• C. Differentiating
• D. Maturing

Explanation: Annular and spiral thick carrier elements usually develop in the protoxylem when the roots or stems are maturing. The maturity of the root or stem is the development of the parts so that the plant can easily become a tree. This is the time when the protoxylem develops or produces annular and spiral thick carrier elements. They also grow plants to provide mechanical support.

162. Anatomically fairly old dicotyledonous root is distinguished from the dicotyledonous stem by:

• A. Absence of secondary phloem
• B. Presence of cortex
• C. Position of protoxylem
• D. Absence of secondary xylem

Explanation: Procambium, which is a meristematic tissue, gives rise to the primary xylem and phloem. In the case of primary xylem, there are two types of xylems that are formed - protoxylem and metaxylem. The protoxylem is the first formed primary xylem. Metaxylem is the primary xylem that is formed after the protoxylem. The protoxylem and metaxylem are arranged in two different ways in the stem and roots. In the stem, the protoxylem is placed towards the center. This is known as an endarch condition. In roots, the protoxylem is arranged towards the periphery. This is known as the exarch condition. Hence, a fairly old dicotyledonous root is distinguished from a dicotyledonous stem by the position of the protoxylem.

163. Vascular tissues in flowering plants develop from:

• A. Periblem
• B. Dermatogen
• C. Phellogen
• D. Plerome

Explanation: Dermatogen is the region or histogen of a single layer of outermost cells formed from the apical meristem. Dermatogen gives rise to the epidermis of the stem and other aerial parts. Periblem is the middle histogen that forms the cortex of the stem and roots. The plerome is the central histogen that forms a stele or part of the stem and roots inner to the endodermis. Part of the plerome that forms vascular tissues is called procambium. The pericycle layer converts into a secondary meristem called cork cambium or phellogen which divides to form a secondary cortex or phelloderm.

164. The length of different internodes in a culm of sugarcane is variable because of:

• A. Size of leaf lamina at the node below each internode
• B. Intercalary meristem
• C. Shoot apical meristem
• D. Position of axillary buds

Explanation: Internode is the part of a plant stem, that occurs between two adjacent nodes. Interca lary meristem are internodal in position and is found in the stem of grasses and other monocotyledonous plants. In early stages the internode is wholly or partially meristematic but later on some of itsparts become matured more rapidly than the rest so a definite continuous sequence of development is maintained i.e., mature tissue left behind whereas new ones grow which later shows variable length.

165. In which one of the following is nitrogen not a constituent?

• A. Idioblast
• B. Bacteriochlorophyll
• C. Invertase
• D. Pepsin

Explanation: The major storage component of Avocado fruit is oil. It is stored in specialized mesocarp cells called idioblast. An idioblast is an isolated plant cell that differs from neighboring tissues. They have various functions such as storage of reserves, excretory materials, pigments, and minerals. They could contain oil, latex, gum, resin, tannin or pigments, etc.

166. Diffuse porous woods are characteristic of plants growing in:

• A. Alpine region
• B. Cold winter regions
• C. Temperature climate
• D. Tropics

Explanation: In most of the gymnosperms, like conifers and cycads, vessels are absent and the wood is made entirely of trach eids. Such wood is known as nonporous. In angiosperms, on the other hand, the wood consists of both tracheids and vessels. The wide vessels appear as pores between otherwise small-sized tracheary elements. Such a wood is known as porous. In porous wood, if vessels have essentially equal diameters and are uniformly distributed throughout the ring, the wood is known as diffuse-porous. It is characteristic of plants growing in the tropics.

167. Four radial vascular bundles are found in:

• A. Dicot root
• B. Monocot root
• C. Dicot stem
• D. Monocot stem

Explanation: The vascular tissue of the root is characterized by radial arrangement of vascular bundles i.e., xylem and phloem occur in separate patches on alternate radii. The number of xylem and phloem groups varies from two to six. But tetrarch condition (four vascular bundles) is more common. Monocot root generally has more than six vascular bundles (polyarch). Vascular bundles in dicot stems are conjoint, collateral or bicollateral, endarch, and open. They are arranged in a ring. In monocot stems the vascular bundles are conjoint, collateral, endarch, and closed. They are scattered in the ground tissue.

168. Vessels are found in:

• A. All angiosperms and some gymnosperm
• B. Most of angiosperms and few gymnosperms
• C. All angiosperms, all gymnosperms and some pteridophyta
• D. All pteridophyta

Explanation: Vessels are long tubelike structures ideally suited for the conduction of water and solutes. These are made up of a row of cylindrical cells arranged in longitudinal series. The partition walls of these cells are perforated and as such the entire structure becomes tubelike. The region of the wall where perforations occur is known as the perforation plate. Vessels are found in the wood of almost all the angiosperms except certain primitive members of the order ranales (vessels dicots), e.g., Trochodendron, Tetracentron, Drimys, Pseudowintera, etc. Vessels also occur in some pteridophytes, such as Selaginella, and in the members of order Gnetales of gymnosperms (e.g., Genetum, Ephedra, and Welwitschia).

169. In plants, Inulin and pectin are:

• A. Reserved material
• B. Wastes
• C. Excretory material
• D. Insect attracting material

Explanation: Inulin is a water soluble fructosan. It is a common reserve food in members of family compositae. Pectin in a mucopolysaccharides and occur in plant cell walls. At the time of fruit ripening wall pectins hydrolyse to give constituent sugars.

170. What happens in plants during vascularisation?

• A. Differentiation of procambium, formation of primary phloem followed by formation of primary xylem
• B. Differentiation of procambium followed by the formation of primary phloem and xylem simultaneously
• C. Formation of procambium, primary phloem and xylem simultaneously
• D. Differentiation of procambium followed by the formation of secondary xylem

Explanation: In plants during vascularisation, differentiation of procambium occurs followed by the formation of primary phloem and xylem simultaneously. The primary xylem is responsible for transporting water and minerals from the roots to the leaves. Primary phloem is responsible for transporting sugars and other organic compounds from the leaves to the rest of the plant. Secondary xylem and secondary phloem are formed from vascular cambium, which is a meristematic tissue that develops from procambium. The secondary xylem and secondary phloem form in concentric rings around the stem or root, increasing the thickness of the vascular system.