SASS Bio Transport in Flowering Plants Handout

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 1 Name: ______________________________( ) Class: ______________ Date: __________ The Tallest of Them All Topic: Nutrition and Transport in Flowering Plants Student’s Handout  Aims At the end of this lesson, you should be able to…  explain how the structure of the xylem enables water to move up the plant,  explain how the leaves are responsible for moving water up the plant,  identify the surface of the leaf that plays a bigger role in moving water up the plant  explain how the number of stomata affects the rate of transpiration in the plant.  Safety Handle capillary tubes with care. Inform your teacher immediately if there is any breakage. Refrain from handling the broken glass pieces on your own.  Activity Handout A: Investigating How Water Travels Up a Plant The tallest tree in Singapore is found in Bukit Timah Nature Reserve. Known as the Seraya tree (Shorea curtisii), it can grow up to a height of 60 m, which is equivalent to a 20-storey HDB block! How is water able to travel against gravity, from the roots, through the xylem to the leaves at the top of such tall trees? In this activity, you will be investigating the features that enable water to travel up a plant.

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 2 Investigation 1: How does the structure of the xylem enable water to move up the plant? In this investigation, the straws and capillary tube are used to model the xylem. Materials  1 large straw  1 regular straw  1 capillary tube  1 half of a petri dish  10 mL of coloured water  1 ruler  1 marker 1. In Table 1.1, trace the circumference of the large straw, regular straw and capillary tube. 2. Use the ruler to measure the diameter of the outline you have drawn. Record your measurements in Table 1.1. 3. Fill the petri dish with the coloured water. 4. Place the large straw into the petri dish with one end firmly on the base of the petri dish (Fig. 1.1). 5. Using the marker, mark out the height that the coloured water travels up to (i.e. height of the coloured water column) in the large straw. 6. Use the ruler to measure the height of the coloured water column. Record your measurement in Table 1.1. 7. Repeat steps 4 to 6 with the regular straw and capillary tube. Fig. 1.1 coloured water petri dish straw

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 3 See  What is the diameter of each straw/tube?  What is the height of the coloured water column in each straw/tube? Table 1.1 Circumference outline Diameter (cm) Height of coloured water column (cm) Large straw Regular straw Capillary tube Think  What is the relationship between the diameter of the straws/tube and the height of coloured water column?  Which straw or tube best represents the structure of a xylem? Why? Wonder  How does a tube with a narrower lumen allow water to travel up the plant?  How well does this model illustrate the function of the xylem?

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 4 Investigation 2: How are the leaves responsible for moving water up the plant? Setups X and Y were set up and left overnight. The water levels in both syringes started at 1 mL. Materials  Setup X  Setup Y 1. Compare setups X and Y. 2. Record the water level in the syringes in both setups in Table 2.1. See What are the water levels in the syringes in setups X and Y after leaving them overnight? Table 2.1 Fig. 2.1 plant cutting plant cutting plasticine 1 mL syringe oil water rubber tubing plasticine Setup YSetup X

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 5 Water level in syringe before experiment (mL) Water level in syringe after experiment (mL) Difference in water level in syringe (mL) Setup X Setup Y Think  What do the differences in water levels in the syringes indicate?  Compare the results for setup X and Y. Suggest a reason for the difference(s) observed.  What is the purpose of setup Y?  What is the purpose of the oil and plasticine used in the experiment? Wonder  How can this experiment be modified to investigate the rate of transpiration?  Since the presence of leaves allows a greater rate of water loss in a plant, how does this link to the adaptations of different plants in different climates?

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 6 Investigation 3: Which surface of the leaf plays a bigger role in moving water up the plant? Materials  1 potted plant (at teacher’s desk)  2 pieces of blue cobalt (II) chloride paper  Transparent adhesive tape  1 pair of scissors  1 stopwatch 1. Use the pair of scissors to cut off one leaf from the potted plant. Identify the upper and lower surfaces of the leaf. 2. Cut one strip of transparent adhesive tape about 2 cm long. 3. Place a piece of blue cobalt (II) chloride paper on the upper surface of the leaf. Blue cobalt (II) chloride paper turns pink in the presence of water. 4. Seal the cobalt (II) chloride paper onto the leaf’s surface using a strip of transparent adhesive tape (Fig. 3.1). 5. Repeat steps 2 to 4 on the lower surface of the leaf. 6. Using the stopwatch, take note of the time taken for each piece of the cobalt (II) chloride paper to turn completely pink. Record your results to the nearest minute in Table 3.1. You may work on the next investigation while waiting for the cobalt (II) chloride paper to change colour. See How long does each piece of cobalt (II) chloride paper take to turn from blue to pink? Table 3.1 Position of cobalt (II) chloride paper Upper surface of leaf Lower surface of leaf Time taken for cobalt (II) chloride paper to turn from blue to pink (min) transparent adhesive tape blue cobalt (II) chloride paper leaf Fig. 3.1

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 7 Think  Which surface of the leaf plays a bigger role in moving water up the plant?  Why do you think so? Wonder  What is a potential limitation of this experiment?  Suggest improvements to this experiment to minimise the limitation.

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 8 Investigation 4: How does the presence of stomata enable water to move up the plant? Materials  2 microscopes, each with a prepared sample of the upper surface of a leaf labelled P and Q  2 microscopes, each with a prepared sample of the lower surface of a leaf labelled R and S Note: The microscopes have been set up for viewing of the upper and lower surfaces of four leaves. Do not adjust the focusing or the positions of the slides. 1. Observe leaf sample P under the microscope. 2. Count the number of stomata on leaf sample P and record your results in Table 4.1. 3. Repeat steps 1 and 2 for samples Q, R and S. 4. Calculate and record the average number of stomata on the upper and lower surfaces of the leaves respectively. See How many stomata are there on the upper and lower surfaces of a leaf? Table 4.1 Upper surface of leaf Lower surface of leaf Sample P Q R S Number of stomata observed Average number of stomata Think  How does the presence of stomata affect the movement of water up a plant?  Compare the number of stomata on the upper and lower surfaces of the leaves. Suggest a reason for the difference (if any).

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 9 Wonder  Are stomata always found in greater abundance on the underside of leaves of all plants? Provide instances where this may not be true.

ST ANDREW’S SECONDARY SCHOOL Chapter 9: Transport in Flowering Plants 10 Handout B: Key Takeaways Consolidate your learning by identifying the key takeaway(s) from each investigation. Investigation 1: How does the structure of the xylem enable water to move up the plant? Investigation 2: How are the leaves responsible for moving water up the plant? Investigation 3: Which surface of the