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During secondary growth, amount of ( a...

During secondary growth, amount of
( a ) Heartwood increases
( b ) Sapwood increases
( c ) Sapwood decreases
( d ) Sapwood remains almost constant

A

Only ( d )

B

( a ) and ( b )

C

( a ) and ( c )

D

( a ) and ( d )

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question regarding the changes in heartwood and sapwood during secondary growth, let's analyze the options step by step: ### Step-by-Step Solution: 1. **Understanding Secondary Growth**: - Secondary growth refers to the increase in thickness of stems and roots in plants, primarily due to the activity of the vascular cambium and cork cambium. 2. **Role of Vascular Cambium**: - The vascular cambium is a layer of meristematic tissue that produces secondary xylem (wood) and secondary phloem. The secondary xylem contributes to the formation of heartwood and sapwood. 3. **Heartwood vs. Sapwood**: - **Heartwood**: This is the inner part of the tree trunk, which is older, denser, and usually darker in color. It provides structural support and does not conduct water. - **Sapwood**: This is the outer part of the xylem, which is younger and actively involved in the conduction of water and nutrients. 4. **Changes During Secondary Growth**: - As secondary growth occurs, the vascular cambium continues to produce new layers of xylem. Over time, the older layers of xylem become heartwood, while the newer layers remain as sapwood. - The amount of heartwood increases as more xylem is produced and older sapwood is converted to heartwood. - Conversely, the amount of sapwood may not significantly increase because as new sapwood is formed, older sapwood is gradually converted to heartwood. 5. **Evaluating the Options**: - (a) Heartwood increases: This is true as secondary growth continues. - (b) Sapwood increases: This is not necessarily true; while new sapwood is formed, the older sapwood is converted to heartwood. - (c) Sapwood decreases: This can be considered true over a long period as older sapwood turns into heartwood. - (d) Sapwood remains almost constant: This is not accurate as the conversion process occurs. 6. **Conclusion**: - The correct answer to the question is (c) Sapwood decreases, as the older sapwood is converted into heartwood during secondary growth. ### Final Answer: (c) Sapwood decreases
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