Aamrapali observed that a young mango sapling's stem bends flexibly during monsoon winds and does not break. Which tissue is responsible for this flexibility? Predict and provide your explanation of the impact if the existing tissue was replaced by sclerenchyma.
The tissue responsible for the flexibility of the young mango sapling's stem is collenchyma. It provides support and flexibility, allowing plant parts like stems to bend without breaking. This flexibility occurs because collenchyma consists of living cells with unevenly thickened corners due to the deposition of pectin, a chemical that gives flexibility like rubber.
If the existing tissue was replaced by sclerenchyma, the stem would lose its flexibility and likely break during the monsoon winds. Sclerenchyma cells have thick walls due to the deposition of lignin, making them hard and strong to form the woody structure. Since most sclerenchyma cells are dead and lack the flexible pectin, the stem would become rigid and unable to bend.
Explanation
The textbook identifies collenchyma as the supporting tissue that provides flexibility to stems due to pectin deposition at the corners of its living cells. Conversely, sclerenchyma is described as having thick walls due to lignin deposition, making the cells hard, strong, and mostly dead. Therefore, replacing the flexible collenchyma with rigid sclerenchyma would cause the stem to lose its ability to bend and snap under wind pressure.
Solution Steps
Step 1: Identify the tissue responsible for flexibility as collenchyma, based on its living cells and pectin deposition.
Step 2: Explain that pectin gives collenchyma rubber-like flexibility, allowing stems to bend without breaking.
Step 3: Analyze sclerenchyma's properties, noting its thick lignin walls and dead cells make it hard and rigid.
Step 4: Conclude that replacing collenchyma with sclerenchyma would make the stem rigid and prone to breaking in the wind.