2. An experiment was designed to study the effect of temperature on the rate of water transport in
plants.
i. Which one is the dependent variable in the experiment?
ii. Why the variable of (i) is called a dependent variable?
3. Draw a labeled diagram of the xylem with important features/ adaptations. (See CW copy)
4. What makes the xylem vessels strong?
5. Xylem and phloem are special types of plant cells. Together they make vascular bundles.
In different parts of the plant, xylems are distributed in regular order. State the position of xylems
in the following.
i. Root
ii. Stem
iii. Leaf
Answers
1. The dependent variable is the variable being tested and measured in an experiment, and is 'dependent' on the independent variable. An example of a dependent variable is depression symptoms, which depends on the independent variable.
2. A dependent variable is what you measure in the experiment and what is affected during the experiment. The dependent variable responds to the independent variable. It is called dependent because it "depends" on the independent variable.
4. Tension is created by the adhesion of water molecules to cell walls as well as by evaporation. This tension pulls the column of water along the xylem vessels. Water has strong cohesive properties, due to the hydrogen bonds between individual molecules, so the column remains an unbroken chain in the xylem vessel.
5. Main function – upwards water transport. The xylem, vessels and tracheids of the roots, stems and leaves are interconnected to form a continuous system of water-conducting channels reaching all parts of the plants. The system transports water and soluble mineral nutrients from the roots throughout the plant.