Fill in the column headings in Table 1.1.
Read the starting and ending positions of the meniscus from the scales in Fig. 1.2 and record them in Table 1.1.
Calculate how far the meniscus moved.
Calculate the rate of movement of the meniscus.
The student had difficulty making an accurate reading of the position of the meniscus. Suggest what this difficulty was and a way of preventing this difficulty when setting up the apparatus. Difficulty [BLANK] Prevention [BLANK]
The stem was sealed in a tight-fitting rubber bung so that its cut end was in the water, as shown in Fig. 1.1. Describe what could occur if this seal was not leak-proof and the effect this would have on the results. Description [BLANK] Effect on results [BLANK]
The tap on the reservoir of the potometer can be opened so that more water can flow into the capillary tube, moving the meniscus back to the start of the scale. The tap is then closed and the apparatus is ready to use again. Explain why the student should take several readings using the same leafy plant stem.
The apparatus in Fig. 1.1 is designed to investigate the uptake of water by a leafy stem. Sometimes this same measurement is described as the rate of water loss (transpiration) from the leafy stem. Explain why the uptake of water and the rate of water loss may not be the same.
Draw a graph of the rate of transpiration against time of day. Connect the points using ruled lines.
Use your graph to determine the rate of transpiration at 11:00. Show your working on the graph.
Leaves have many microscopic openings called stomata through which water evaporates and is lost from the leaf. Stomata can be open so that more water vapour is lost, or closed so that less water vapour is lost. Use this information, your graph and the data given to explain what is happening to the stomata between 04:00 and 12:00.
A student read that the rate of transpiration is lowest when the air around a leafy plant is still. Design an investigation using the apparatus in Fig. 1.1 to find out whether this statement is correct.
Identify the independent variable in your investigation.
A student wanted to discover whether some liquid collected from a vein in a green leaf contained glucose. Describe a test for glucose that could be carried out, including how it would show that glucose was present.