Given below is the diagram of an experimental setup to study the process of Transpiration. Cobalt chloride papers are fixed on the upper as well as lower surface of the leaf. Answer the questions that follow: Given below is the diagram of an experimental setup to study the process of Transpiration. Cobalt chloride papers are fixed on the upper as well as lower surface of the leaf. Answer the questions that follow:
After about an hour, what change if any, would you expect to find in the cobalt chloride paper placed on the upper and lower surface of the leaf?
Topic: Result of the cobalt chloride experiment
Try it
Pick an option and check your answer. The full worked answer is below either way.
Answer
(c) Upper surface – less pink, Lower surface – more pink..
BOTH papers turn pink, because transpiration occurs from both surfaces — but the LOWER one turns MORE pink and faster, because the lower epidermis has many more stomata and therefore loses more water.
THE KEY INSIGHT, and what separates (c) from the other options: the difference is one of DEGREE, not of presence and absence. The upper surface does transpire, just less. Options (a) and (b) claim the lower paper stays BLUE, which would mean no transpiration at all from the side that actually transpires most — exactly backwards.
Option (d) reverses the comparison.
WHEN A QUESTION ASKS FOR A COMPARISON, look for the option expressing MORE and LESS rather than YES and NO. Biological differences are usually differences of degree.
Upper surface – less pink, Lower surface – more pink..