Question 25
Which side of a leaf loses most water? Eight similar leaves from the same kind of plant are labelled A–H. Apply petroleum jelly as follows: A/B none; C/D upper surface only; E/F lower surface only; G/H both surfaces. Hang the leaves in their original order and compare their measured mass losses after at least one day. Use eight paperclips, a washing line (or string between two retort stands), a sensitive balance, and filter paper on the balance to protect it from petroleum jelly. Choose similar-sized leaves, keep each beside its letter before hanging, apply the treatments, and measure each mass after coating and before drying. After at least one day, measure again.
