Question

24 six bean seeds were soaked in cold water. three of them were boiled and cooled. the boiled and the non-boiled seeds were chopped up and then placed on the surface of agar jelly containing starch.

after two days, all the seeds were removed and the jelly was tested with iodine solution.

the diagram shows the result of the experiment.

what is the explanation for the results with the non-boiled bean seeds?

a they absorb iodine.
b they absorb starch.
c they contain amylase.
d they contain maltase.

Explanation:

Analyze the experimental setup

The experiment involves placing chopped boiled and non-boiled bean seeds on agar jelly containing starch. After two days, the seeds are removed, and the jelly is tested with iodine solution. Iodine turns blue-black in the presence of starch, and remains yellow-brown if starch is absent.

Interpret the results

On the side with boiled seeds, the entire area turns blue-black, including where the seeds were placed. This indicates starch is still present. On the side with non-boiled seeds, the areas where the seeds were placed turn yellow-brown, while the surrounding area turns blue-black. This indicates starch has been broken down (digested) in those specific spots.

Identify the biological cause

Boiling denatures enzymes. Since the boiled seeds did not break down starch, the active agent in the seeds must be an enzyme. The non-boiled seeds successfully digested the starch in the agar. The enzyme responsible for breaking down starch into simpler sugars is amylase. Therefore, the non-boiled seeds contain active amylase.

Answer:

• (A) They absorb iodine.
• (B) They absorb starch.
• (C) They contain amylase. (Correct answer)
• (D) They contain maltase.