Photosynthesis Diagram Labeling Worksheet

Name: ___________________________ Date: ________________

Section 1: Label the Chloroplast Diagram

Below is a simplified diagram of a chloroplast. For each numbered structure, write the correct term on the line provided.

[Insert chloroplast diagram with labels 1–6]

1. ________________________________
   
   
   
2. ________________________________
   
   
   
3. ________________________________
   
   
   
4. ________________________________
   
   
   
5. ________________________________
   
   
   
6. ________________________________
   
   
   

Terms to choose from:

• Outer membrane
• Inner membrane
• Thylakoid
• Granum
• Stroma
• Photosystem II

Section 2: Match the Terms to Definitions

Write the letter of the correct definition on the line next to each term.

7. Thylakoid _______________________
   
   
   
8. Granum __________________________
   
   
   
9. Stroma __________________________
   
   
   
10. Photosystem II ___________________
    
    
    
11. Electron Transport Chain __________
    
    
    

Definitions:

A. Stack of membrane-bound sacs where light reactions occur.

B. Individual membrane sac containing chlorophyll molecules.

C. Fluid-filled space surrounding the thylakoid membranes.

D. Protein complex that absorbs light and initiates electron flow by splitting water molecules.

E. Series of protein carriers embedded in the thylakoid membrane that shuttle electrons and pump protons.

Section 3: Short Answer

In 2–3 sentences, explain how light energy is converted into chemical energy during the light-dependent reactions of photosynthesis.

Interactive Photosynthesis Simulation

Use this online simulation to explore how light intensity and CO₂ concentration affect the rate of oxygen production during photosynthesis.

Simulation Link: PhET Photosynthesis Simulation

Instructions

1. In pairs, open the simulation link on your device.
2. Under Light Intensity, set the slider to Medium (≈50%).
3. Under CO₂ Concentration, leave at Ambient (≈0.04%).
4. Run Trial A:
   • Click Play and observe the O₂ bubble rate.
   • Record observations in your lab notebook.
5. Run Trial B (Light Change):
   • Increase Light Intensity to High.
   • Observe and record how O₂ production changes.
6. Run Trial C (CO₂ Change):
   • Return light to Medium.
   • Change CO₂ Concentration to High (≈0.1%).
   • Observe and record results.

Data Table (Lab Notebook)

Reflection Questions

1. How did increasing light intensity affect O₂ production?
   
   
   
2. What effect did changing CO₂ concentration have on the rate of photosynthesis?
   
   
   
3. Based on your observations, why are both light and CO₂ essential for the light-dependent reactions?
   
   
   
   
   
   

Leaf Disk Experiment Instructions

Teacher Protocol (Prep & Demonstration)

1. Materials Needed:

   • Fresh spinach or geranium leaves
   • Hole punch (5 mm diameter)
   • 1% sodium bicarbonate solution (NaHCO₃ in distilled water)
   • 3 mL syringe without needle or vacuum infiltration apparatus
   • Clear cups or beakers (one per group)
   • Desk lamp with 100 W bulb (light source)
   • Stopwatch or timer
   • Pipette or dropper
   • Student Lab Notebooks
   • Marker and labels

2. Prepare Bicarbonate Solution (5 min):

   • Dissolve 1 g sodium bicarbonate in 100 mL distilled water. Stir until fully dissolved.
   • Pour solution into a labeled beaker.

3. Punch Leaf Disks (5 min):

   • Using the hole punch, create at least 10 leaf disks per group. Remove any midrib tissue to ensure uniformity.
   • Place disks into a medium-sized Petri dish.

4. Infiltrate Disks (5 min):

   • Transfer disks and ~5 mL of bicarbonate solution into a 3 mL syringe. Seal the tip with your finger.
   • Pull back on the plunger to create a vacuum for ~10 s. Release to draw solution into disks (they will sink). Repeat if necessary until disks sink easily.

5. Set Up Experimental Station (2 min):

   • Distribute 5 infiltrated disks into each group’s clear cup filled with 10 mL fresh bicarbonate solution.
   • Position the lamp ~10 cm above each cup.

6. Conduct Demonstration (3 min):

   • Turn on the lamp; start the timer.
   • Show students how to observe disks rising as O₂ accumulates.
   • Record approximate flotation time for 5 disks.

7. Discuss Variables & Predictions (3 min):

   • Ask: “What factors might change the flotation time?” (light intensity, CO₂ concentration, leaf type).
   • Have students predict results for a second trial (e.g., half-light intensity).

Student Protocol (Investigation)

Objective

Determine how light intensity affects the rate of photosynthesis by measuring the time for leaf disks to float.

Procedure

1. Label your cup (Group ___).
2. Obtain 5 pre-infiltrated leaf disks.
3. Place disks in your cup and fill with bicarbonate solution.
4. Position the cup under the lamp at the teacher-specified height.
5. Start Timer as soon as the light is on.
6. Record Time when each disk rises to the surface. Stop timing when all 5 disks float.
7. Repeat for a second trial with altered light intensity (e.g., move lamp farther away).

Data Table

Analysis Questions

1. How did changing the light intensity affect the time for disks to float?
   
   
   
2. What does flotation time indicate about the rate of photosynthesis?
   
   
   
3. Suggest one improvement to make this experiment more reliable.