- Which of the following is characteristic of dicot leaves?
a) Parallel venation
b) Presence of guard cells
c) Reticulate venation
d) Absence of vascular tissue
Answer: c) Reticulate venation
Explanation: Dicot leaves typically exhibit reticulate venation, where the veins form a network, in contrast to monocot leaves, which show parallel venation.
- Which of the following structures is produced by cork cambium?
a) Phellem
b) Primary xylem
c) Phloem fibers
d) Root cap
Answer: a) Phellem
Explanation: Phellem, also known as cork, is produced by the cork cambium and forms a protective outer layer in plants undergoing secondary growth.
- Which of the following is a function of the vascular cambium?
a) Production of primary phloem
b) Formation of secondary xylem
c) Water absorption
d) Storage of food
Answer: b) Formation of secondary xylem
Explanation: The vascular cambium produces secondary xylem (wood) on the inside and secondary phloem on the outside during secondary growth in dicotyledonous plants.
- What kind of vascular bundles are present in dicot stems?
a) Collateral and open
b) Collateral and closed
c) Radial
d) Bicollateral
Answer: a) Collateral and open
Explanation: In dicot stems, the vascular bundles are collateral (xylem and phloem arranged on the same radius) and open, meaning they have a cambium layer between the xylem and phloem.
- In which of the following tissues are casparian strips found?
a) Epidermis
b) Endodermis
c) Pericycle
d) Pith
Answer: b) Endodermis
Explanation: Casparian strips are present in the endodermal cells of roots and prevent the passive flow of water and solutes into the vascular system, forcing selective absorption.
- The epidermis of the leaf is covered with a waxy layer called:
a) Cuticle
b) Phellem
c) Periderm
d) Endodermis
Answer: a) Cuticle
Explanation: The cuticle is a waxy layer secreted by the epidermis of leaves and stems. It helps reduce water loss by acting as a barrier to evaporation.
- Which cells surround the stomata and regulate their opening and closing?
a) Mesophyll cells
b) Guard cells
c) Trichomes
d) Epidermal cells
Answer: b) Guard cells
Explanation: Guard cells flank each stomatal pore and control its opening and closing by changing their turgidity, regulating gas exchange and transpiration.
- In a typical dicot stem, secondary growth occurs due to the activity of:
a) Apical meristem
b) Cork cambium
c) Vascular cambium
d) Endodermis
Answer: c) Vascular cambium
Explanation: Secondary growth in dicot stems is caused by the activity of the vascular cambium, which produces secondary xylem and phloem, increasing the girth of the plant.
- Which of the following tissues is responsible for transporting sugars throughout the plant?
a) Xylem
b) Phloem
c) Parenchyma
d) Sclerenchyma
Answer: b) Phloem
Explanation: Phloem is responsible for the transport of sugars (mainly sucrose) and other organic nutrients from the leaves to other parts of the plant.
- What is the function of collenchyma cells in plants?
a) Water transport
b) Structural support
c) Photosynthesis
d) Absorption of nutrients
Answer: b) Structural support
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