It is designed for 9th
to 12th graders. The principle of photosynthesis will be studied. It needs about 50 minutes.
- Students will know that oxygen
is one of the reactants for photosynthesis and carbon dioxide is one of
the products of photosynthesis.
Standards: (biology/life, science content
standards for grades nine to twelve)
1. a. Students know cells are enclosed within
semipermeable membranes that regulate their interaction with their
membrane consists of two layers of lipid molecules organized
1. c. Students know how prokaryotic cells, eukaryotic
cells (including those from plants and animals), and viruses differ in
complexity and general structure.
1. f. Students know usable energy is captured from
sunlight by chloroplasts and is stored through the synthesis of sugar from
- young spinach leaves
- one 100 ml beaker and one 500ml
- 5 ml sodium bicarbonate/detergent
- plastic 10-cc syringe
- light source
- Use the straw to punch five
disks from a spinach leaf.
- Fill one 100ml beaker halfway
with the sodium bicarbonate / detergent solution. Fill the 500ml beaker
- Remove the plunger from the
syringe and place the spinach leaf disks into the syringe. Insert the
plunger and draw 5ml of the sodium bicarbonate / detergent solution into
- Hold the syringe so that the
tip is pointing upwards. Push on the plunger to sqirt out any air in the
- Place your finger on the tip
of the syringe and withdraw the plunger to form a vacuum, but be careful
not to pull the plunger all the way out of the syringe. Shake the syringe
a few times while your finger is on the tip.
- Take your finger off the tip
of the syringe. This causes the leaf disks to sink to the bottom of the
- Place your finger over the tip
of the syringe and turn it so the tip is pointing down. Carefully remove
the plunger and pour the contents of the syringe into the beaker of
beaker with leaf disks under the light source and immediately start the
stopwatch. Record the time it takes for each leaf disk to float to the top of
Students know about chemical reactions.
Students need to know that photosynthesis is a type of chemical reaction
happening in a plant cell (chloroplast). Photosynthesis will be affected by
- Why did the leaf disk sink
after you created a vacuum in the syringe?
- Why did the leaf disk go back
up to float in the water after you put the leaf disk in water under a