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Plants require water for survival - Leaving Cert Biology - Question 15(c) - 2022
Question 15(c)
Plants require water for survival. (i) By what process does water enter the root hairs? (ii) Draw a large diagram of a transverse section of a root and label the f... show full transcript
Worked Solution & Example Answer:Plants require water for survival - Leaving Cert Biology - Question 15(c) - 2022
Step 1
By what process does water enter the root hairs?
Answer
Water enters the root hairs through the process of osmosis. In this process, water moves from an area of higher water concentration in the soil to an area of lower water concentration inside the root hairs. This is facilitated by the semi-permeable membranes of the root hair cells.
Step 2
Draw a large diagram of a transverse section of a root and label the following tissues: dermal; ground; vascular.
Answer
To illustrate a transverse section of a root:
- Draw a large circle to represent the overall structure of the root.
- Label the outermost layer as dermal tissue, which serves as a protective barrier.
- Inside the dermal tissue, designate a layer as ground tissue, responsible for storage and support.
- At the center, indicate the vascular tissue, which is crucial for the transport of water and nutrients.
- Clearly label each section in the diagram appropriately.
Step 3
Step 4
Describe in detail the upward movement of water in plants.
Answer
The upward movement of water in plants involves several mechanisms:
- Root Pressure: Water enters the root hairs through osmosis, creating a pressure that pushes water upwards through the xylem.
- Cohesion and Adhesion: Water molecules exhibit cohesion (attraction between water molecules) and adhesion (attraction to the walls of xylem vessels). This results in the formation of a continuous water column.
- Transpiration Pull: Water evaporates from the stomata in the leaves, generating a negative pressure that pulls water up from the roots through the xylem.
- Tension and Pressure Difference: The combination of root pressure and transpiration creates a tension and pressure difference that facilitates the movement of water against gravity, ensuring that all parts of the plant receive the necessary moisture.