Fundamentals of Biology
LABORATORY EXERCISE #4
CELLULAR ENERGY TRANSFORMATIONS
PHOTOSYNTHESIS AND RESPIRATION
Name:________________________________
SR #: __________
Date:__________
Section:________
Learning Objectives:
1. Describe the processes important in living organisms specifically the transformation and
production of energy during photosynthesis and respiration
2. Recognize that photosynthesis and respiration are performed by green leaves
3. Relate light intensity with the rate of photosynthesis
4. Prove that varying light intensity has no effect with rate of respiration
Materials
500ml beaker
Distilled water
Meter stick
Lead wire
Table lamp (100W)
Green leaves
Hydrilla plant
Muslin tape
Rubber stoppers
Thermometer
Test tubes
Black polythene bag
Thread
Sodium hydrogen carbonate
Hydrogen carbonate
indicator
Procedure
A. Analyze the effect of light intensity in photosynthesis.
1. Prepare all the needed materials and construct the set-up by referring to figure 1
2. Place a table lamp (100W) at distances (d) of 250 cm, 200cm, 150cm, 100 cm, 50cm, 20cm
and 10 cm away from the water plant.
3. At each distance, wait a few minutes until the rate of evolution of bubbles becomes
steady. Count the number of bubbles given off during a one-minute period. Present the
results graphically.
4. Answer items 1-2 in the worksheet.
Figure 1. Experimental set-up for light intensity in photosynthesis.
B. Investigate the effect of different light penetrations on leaves.
1. Get four test tubes, each containing 1 ml of hydrogen carbonate solution and label them
A-D.
2. Prepare rubber stoppers, thread, leaves, black polythene bag and muslin bandage. Use
these materials as the experimental set-up (figure 2) is assembled.
3. Set-up a lamp about 10 cm from the beakers. Observe any color change on hydrogen
carbonate indicator solution in each test tube after one hour.
4. Answer item 3 in the worksheet.
Figure 2. Experimental set-up for different light penetrations on leaves.
A – Covered with Black polythene bag
B – Covered with Muslin bandage
C – No cover but with leaf
D – No cover and no leaf
DATA:
Distance from the plant
250 cm
200cm
150cm
100 cm
50cm
20cm
10 cm
Bubbles per minute
0
5
10
15
20
25
30
Fundamentals of Biology
LABORATORY EXERCISE #4
CELLULAR ENERGY TRANSFORMATIONS
PHOTOSYNTHESIS AND RESPIRATION
Name:________________________________
SR #: __________
Date:__________
Section:________
ANSWER SHEET
A. Present the result of light intensity in graphical form.
B. Establish a correlation between the number of bubbles given off per minute and light intensity.
C. Summarize the results of procedure b by completing table 1. Indicate the explanation and the
processes involved in the activity.
Table 1. Effects of different light penetrations on leaves
Test Tube
Original color of
Color change
the solution
A
B
C
D
Explanation
Process Involved