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Explain how water enters root hairs and then passes to the vascular tissue - Leaving Cert Biology - Question 14(c) - 2014
Question 14(c)
Explain how water enters root hairs and then passes to the vascular tissue. In which of the vascular tissues will water now rise through the plant? Give two featur... show full transcript
Worked Solution & Example Answer:Explain how water enters root hairs and then passes to the vascular tissue - Leaving Cert Biology - Question 14(c) - 2014
Step 1
Explain how water enters root hairs and then passes to the vascular tissue.
Answer
Water enters root hairs predominantly through a process called osmosis. The concentration of soil water (which is typically more diluted) is lower than that of the cytoplasm of root cells, making the internal environment more concentrated. Consequently, water moves into the root hair cells from the soil by osmosis.
Once inside the root hairs, water travels from cell to cell, creating a pathway that leads to the vascular tissue, primarily through the porous cell walls and through specialized structures known as plasmodesmata, which allow for water movement between adjacent cells.
Step 2
Step 3
Give two features of the tissue referred to in (ii) that facilitate this upward movement of water.
Answer
- The xylem is narrow with continuous tube-like structures allowing a smooth passage for water.
- It has no cell contents that obstruct the flow of water, and its walls are thickened, which helps to maintain structural integrity while allowing efficient water transport.
Step 4
Name and briefly explain any two processes involved in the upward movement of water in plants.
Answer
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Root Pressure: Water entering the roots creates a pressure that pushes water up through the xylem vessels. This occurs when water accumulates in the root and forces it upward.
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Transpiration: This is the process by which water vapor is lost from the leaves through stomata, creating a negative pressure that pulls water upwards from the roots through the xylem.