Q11. The tissue that transports water and minerals from roots to other plant parts is:
a) Phloem
b) Xylem
c) Cambium
d) Cortex
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Correct Answer: b) Xylem
Explanation: Xylem is the vascular tissue specialized for the conduction of water and dissolved minerals from the roots upwards to the stem, leaves, and other aerial parts of the plant. Phloem transports food. Cambium is for secondary growth. Cortex is ground tissue.
Q12. The tissue responsible for translocation of food materials from leaves to storage organs and growing regions is:
a) Xylem
b) Phloem
c) Cambium
d) Epidermis
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Correct Answer: b) Phloem
Explanation: Phloem is the vascular tissue specialized for translocation of organic nutrients (food), primarily sugars, synthesized in leaves (source) to storage organs (sink) and growing regions of the plant. Xylem transports water. Cambium is for secondary growth. Epidermis is protective outer layer.
Q13. Which type of tissue is absent in monocot stems?
a) Epidermis
b) Vascular bundles
c) Ground tissue
d) Vascular cambium
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Correct Answer: d) Vascular cambium
Explanation: Monocot stems lack vascular cambium. This absence is why monocot stems do not exhibit secondary growth (increase in girth). Dicot stems possess vascular cambium, which leads to secondary growth. Epidermis, vascular bundles, and ground tissue are present in both monocot and dicot stems, although their arrangement differs.
Q14. In dicot roots, the vascular bundles are:
a) Radial
b) Conjoint
c) Concentric
d) Collateral
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Correct Answer: a) Radial
Explanation: In dicot roots (and monocot roots), the vascular bundles (xylem and phloem) are arranged in a radial manner, meaning xylem and phloem bundles are present in separate radii, alternating with each other. This radial arrangement is characteristic of roots. Conjoint, concentric, and collateral arrangements are found in stems and leaves, not roots.
Q15. Open vascular bundles are characterized by the presence of:
a) Xylem only
b) Phloem only
c) Cambium
d) Pith
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Correct Answer: c) Cambium
Explanation: Open vascular bundles, typically found in dicot stems and roots, are called ‘open’ because cambium (vascular cambium) is present between xylem and phloem. This cambium allows for secondary growth. Closed vascular bundles, found in monocot stems and leaves, lack cambium, hence no secondary growth.
Q16. Which type of vascular bundle is characterized by xylem and phloem arranged on the same radius with phloem located outside?
a) Radial
b) Conjoint collateral
c) Conjoint bicollateral
d) Concentric
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Correct Answer: b) Conjoint collateral
Explanation: Conjoint collateral vascular bundles are typical of dicot and monocot stems and leaves. In this type, xylem and phloem are situated on the same radius, with phloem positioned towards the outer side and xylem towards the inner side. Radial is in roots, concentric is xylem surrounded by phloem or vice versa, and bicollateral has phloem on both sides of xylem.
Q17. Periderm is a protective tissue in older stems and roots, consisting of:
a) Epidermis and cortex
b) Cortex and endodermis
c) Cork cambium, cork, and secondary cortex
d) Epidermis, cork cambium and cork
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Correct Answer: c) Cork cambium, cork, and secondary cortex
Explanation: Periderm is the outer protective layer that replaces the epidermis in older stems and roots after secondary growth begins. It consists of cork cambium (phellogen), cork (phellem), and secondary cortex (phelloderm). Cork cells are dead and suberized, making periderm impermeable to water and gases, offering protection.
Q18. Lenticels are small pores in the bark, involved in:
a) Photosynthesis
b) Transpiration
c) Gaseous exchange
d) Water absorption
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Correct Answer: c) Gaseous exchange
Explanation: Lenticels are raised, porous areas in the bark of woody stems and roots, formed due to the activity of phellogen. They facilitate gaseous exchange between the atmosphere and the internal tissues of the stem, as the cork layer is impermeable to gases. Photosynthesis occurs in leaves, transpiration mainly through stomata, and water absorption by roots.
Q19. Which of the following is NOT a function of roots?
a) Absorption of water and minerals
b) Anchorage of the plant
c) Synthesis of food
d) Storage of food reserves
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Correct Answer: c) Synthesis of food
Explanation: Roots are primarily involved in absorption of water and minerals from the soil, providing anchorage to the plant, and storage of food reserves (like in sweet potato, carrot). Synthesis of food (photosynthesis) is primarily the function of leaves and stems containing chloroplasts, not roots which typically lack chlorophyll and are underground.
Q20. The region of root involved in active water absorption is:
a) Root cap region
b) Region of elongation
c) Region of maturation
d) Region of meristematic activity
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Correct Answer: c) Region of maturation
Explanation: The region of maturation (differentiation) in roots is where root hairs are developed from epidermal cells. Root hairs are thin-walled extensions that greatly increase the surface area for water and mineral absorption from the soil. Root cap protects the apex, region of elongation is for root growth in length, and meristematic region is for cell division.