Free Growth and Development MCQs with Answers

171. Cork cambium and vascular cambium are:

• A. Parts of secondary xylem and phloem
• B. Parts of pericycle
• C. Lateral meristem
• D. Apical meristem

Explanation: Lateral meristems are cylinders of dividing cells. They are present in dicots and gymnosperms. Vascular and cork cambium are examples of the lateral meristem. They play an important role in the increase in diameter of stem and root and secondary growth are determinate i.e. they grow to a certain size and then stop e.g. leaves, lowers, and fruits; while others are indeterminate i.e. they- grow by meristems that continually replenish themselves, remaining youthful e.g. vegetative root and stem.

172. Monocot leaves possess:

• A. Intercalary meristem
• B. Lateral meristem
• C. Apical meristem
• D. Mass meristem

Explanation: Monocot leaves possess intercalary meristem. Intercalary meristem are responsible for localised growth. Perhaps they have been separated or detached from the mother meristem e.g., meristem present at the base of leaves in many monocots, in the internode of grasses, at the top of peduncles of Plantago and Taraxacum etc.

173. Collenchyma occurs in the stem and petioles of:

• A. Xerophytes
• B. Monocots
• C. Dicot herbs
• D. Hydrophytes

Explanation: Collenchyma occurs in the stem and petioles of dicot herbs. Collenchyma is a type of ground tissue found in plants that provide mechanical support. It consists of elongated cells with thickened cell walls, which can vary in thickness and distribution. Collenchyma cells often occur in strands or continuous cylinders beneath the epidermis in stems and petioles of dicotyledonous (dicot) herbs. They provide flexible support to the growing plant and help resist bending or breaking. While collenchyma can also be found in other plant types, such as monocots, xerophytes (plants adapted to arid environments), and hydrophytes (plants adapted to aquatic environments), it is most commonly associated with the stem and petioles of dicot herbs.

174. Collenchyma occurs in:

• A. Herbaceous climbers
• B. Woody climbers
• C. Climbing stems
• D. Water plants

Explanation: Collenchyma occurs in climbing stems. Collenchyma occurs in the stem and petioles of dicot herbs. Due to the deposition of pectin, it has high water-retaining capacity. Since pectin appears at the angles, it becomes a spongy tissue. The collenchyma is a mechanical tissue that gives tensile strength to the plant.

175. Pericycle of roots produces:

• A. Mechanical support
• B. Lateral roots
• C. Vascular bundles
• D. Adventitious buds

Explanation: Pericycle of root produces lateral roots. Endodermis is followed by pericycle. Usually, it is a continuous layer but in some monocots, it is interrupted by the xylem and phloem. It is the site of origin of lateral roots and cork cambium. The root branches are, therefore described as endogenous in origin.

176. For union between stock and scion in grafting which one is the first to occur:

• A. Formation of callus
• B. Production of plasmodesmata
• C. Differentiation of new vascular tissues
• D. Regeneration of cortex and epidermis

Explanation: Grafting is a techinque in which cambium bearing shoot (scion = graft) of one plant is joined to cambium bearing stump (root system = stock) of a related plant through different unions like tongue grafting, wedge grafting etc. In grafting union between stock and scion produces undifferentiated mass of cells called callus. Therefore, for union between stock and scion in grafting, first to occur is the formation of callus. Callus is more orless corky secondary tissue developed lay woody plants over a wound. It is derived from cambium.

177. Bordered pits are found in:

• A. Sieve cells
• B. Vessel wall
• C. Companion cells
• D. Sieve tube wall

Explanation: Bordered pits are specialized structures that allow water to pass between cells in the xylem, the water-transporting tissue of plants. They are found in the walls of vessels, which are long, hollow cells that transport water up the plant.

178. Vascular cambium produces:

• A. Primary xylem and primary phloem
• B. Secondary xylem and secondary phloem
• C. Primary xylem and secondary phloem
• D. Secondary xylem and primary phloem

Explanation: The vascular cambium is a lateral meristem found in the stems and roots of woody plants. It is responsible for the production of secondary vascular tissues, namely secondary xylem (wood) and secondary phloem.

179. Which exposed wood will decay faster?

• A. Sapwood
• B. Softwood
• C. Wood with lot of fibres
• D. Heartwood

Explanation: Sapwood will decay faster. Sap wood is less durable because it is susceptible to attack by pathogens and insects. The outer light-colored functional wood which contains living cells is called sapwood. It is prone to attack by pathogens and insects. So it easily undergoes decomposition, when exposed to insects and pathogens

180. A narrow layer of thin-walled cells found between the phloem/bark and wood of a dicot is:

• A. Cork cambium
• B. Vascular cambium
• C. Endodermis
• D. Pericycle

Explanation: A narrow layer of thin-walled cells found between phloem/bark and wood of dicot is vascular cambium. Vascular cambium present inside a vascular bundle is called as intrafascicular cambium or fascicular cambium. The vascular cambium is a meristematic tissue.