Download Notes(Credits to Mustafa Asif) NotesFeatures and adaptations of the root hair cell
Features and adaptations of the xylem
Features and adaptations of the phloem
Cross section of a stemCross section of a rootAbsorption of water in the rootsTranspiration PullStructured Question Worked Solutions1. The diagram below shows a xylem vessel.Are xylem vessels living or dead structures? Give a reason. Solution They are dead structures as they do not contain protoplasm. 2. What are the main functions of xylem vessels? Solution To transport water and dissolved mineral salts from the roots to the stems and leaves, and to provide mechanical support to the plant. 3. State three ways in which xylem vessels are adapted to their functions. Solution
4. Explain the processes involved in the movement of water from the soil into the conducting tissue of a plant root. Solution
5. Products of photosynthesis, such as sucrose, are translocated via the phloem from sites of production in green leaves to places where they are utilised, such as seeds, fruits, roots, and new leaves. These places are known as 'sinks' a. Describe a pathway by which a sucrose molecule is transported from the leaf to a sink such as a fruit. b. Describe an experiment that can demonstrate the process described in (a). c. Suggest and explain one reason why a sucrose molecule may be transported to a particular sink and not to other sinks. Solution a. A pathway is the route taken by the sucrose molecule from the cells in the leaf to the fruit. The sucrose molecule moves from the mesophyll cells in the leaf to the phloem in a vascular bundle of the leaf. This is followed by moving to the phloem in a vascular bundle of the fruit and finally to the cells of the fruit. b. step 1: cut off a complete ring of bark including the phloem and cambium from the main stem of a woody twig. This will leave the xylem exposed. Place the twig in water with the ring immersed. step 2: prepare another twig that has a cut ring above the water level. step 3: set up a control using an unringed twig step 4: observe the twigs daily. Note where roots or swellings appear. Make drawings of observations. c. Sucrose can be converted into glucose. Glucose is required for tissue respiration. Sucrose will first be transported to sinks which have higher rates of metabolic activity, such as growing points (shoots and root tips) 6. Describe how water from the capillary tube enters the shoot to reach one of the leaves. Solution Transpiration by the leaves creates a transpiration pull, which sucks water up the xylem vessels to the leaves, water in the container enters the shoot to replace that lost in transpiration. Capillary action, whereby water tends to move up very narrow tubes, also allows water to move through the capillary tube and through the xylem vessels in the stem to reach the leaves. |
Biology >