Activity 8: Activity Overview

This activity will show the role of sunlight in photosynthesis. With the use of the chemical iodine, the students are allowed to figure out whether or not starch is produced. This would lead them to answer whether or not photosynthesis occurred. Using petroleum jelly, a substance that the students are familiar with, they are encouraged to examine what part of the leaf allows for gas exchange – (carbon dioxide is taken in and oxygen is released) which is crucial for photosynthesis
and respiration to happen.

Preparation and Materials Needed
Preparation
Two weeks before the experiment, you can start requesting the students to bring baby food jars together with their lids. They will be used for the isopropyl alcohol.

A week before the scheduled experiment, start looking for a plant to be used and be sure that you have them available no later than four days before the experiment. Since two plants of the same kind are used for each group, make sure that they are almost of the same size. The plants should have small leaves and at least eight of them. (Although the experiment calls for 5 leaves, allow 3 more leaves for possible mistakes.) It is advisable to get plants in a 4-inch pot. This will allow less space for exposure to light and darkness three days before the actual handling by the students.

If you do not have hot plates, you can use the microwave to provide the students with hot (60??qC) tap water. Use Erlenmeyer flasks for easier manageability.

Materials/Equipment Needed (for the class)

• microwave
• Erlenmeyer flasks

• 2 4-inch potted plants
• 1 pair of scissors
• 1 beaker
• 1 baby food jar with lid
• 2 forceps
• isopropyl alcohol
• hot (60??qC) tap water
• petroleum jelly
• thermometer
• 4 sets of gloves
• 4 goggles
• 4 aprons
• soap
• paper towels

• the baby food jar with the isopropyl alcohol from Day 1
• 1 baby food jar
• the same forceps used for the isopropyl alcohol from Day 1
• 1 forceps
• 2 Petri dishes
• Lugol’s iodine solution
• white paper
• 4 sets of gloves
• 4 goggles
• 4 aprons
• soap
• paper towels

• the same 4-inch potted plant originally kept in the dark
• and then was exposed to sunlight from Day 1
• Histoclear
• 8 swab applicators
• paper towels
• 1 baby food jar
• Lugol’s iodine solution
• 4 Petri dishes
• 4 white papers
• 4 sets of gloves
• 4 goggles
• 4 aprons
• soap