Q81. Stele includes:
[A] Cortex and pericycle
[B] Endodermis and cortex
[C] Pericycle and vascular bundles
[D] Epidermis and cortex
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Correct Answer: [C] Pericycle and vascular bundles
Explanation: Stele is the central core of the stem or root, inside the endodermis. It includes pericycle, vascular bundles (xylem and phloem), pith (if present), and sometimes medullary rays. Cortex and epidermis are outside the stele. Endodermis forms the inner boundary of cortex and outer boundary of stele.
Q82. Pith is absent in roots of:
[A] Monocots
[B] Dicots
[C] Both monocots and dicots
[D] Some dicots
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Correct Answer: [D] Some dicots
Q83. The main conducting elements of xylem are:
[A] Xylem parenchyma and xylem fibres
[B] Tracheids and vessels
[C] Sieve tubes and companion cells
[D] Sieve cells and albuminous cells
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Correct Answer: [B] Tracheids and vessels
Q84. The main conducting elements of phloem in angiosperms are:
[A] Tracheids and vessels
[B] Sieve tubes and companion cells
[C] Sieve cells and albuminous cells
[D] Phloem parenchyma and phloem fibres
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Correct Answer: [B] Sieve tubes and companion cells
Explanation: Sieve tubes and companion cells are the main conducting elements of phloem in angiosperms, responsible for food translocation. In gymnosperms and pteridophytes, sieve cells and albuminous cells are the conducting elements of phloem. Phloem parenchyma is for storage, phloem fibers for support.
Q85. Which of the following is a living mechanical tissue?
[A] Parenchyma
[B] Collenchyma
[C] Sclerenchyma
[D] Xylem parenchyma
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Correct Answer: [B] Collenchyma
Q86. Which of the following is a dead mechanical tissue?
[A] Collenchyma
[B] Parenchyma
[C] Sclerenchyma
[D] Epidermis
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Correct Answer: [C] Sclerenchyma
Explanation: Sclerenchyma is a dead mechanical tissue because its cells are dead at maturity and have thick, lignified cell walls providing rigidity, strength, and mechanical support. Collenchyma and parenchyma are living tissues. Epidermis is primarily protective and cells are living.