8.1 LAB
NAME_____________________________HR____
TITLE: Photosynthesis & Respiration
STUDENT LEARNING OBJECTIVE:
-IDENTIFY the relationship between the processes of photosynthesis and respiration.
BACKGROUND:
Green plants use sunlight to make glucose. To do so, the plant must use carbon dioxide and water in a process called
photosynthesis. The glucose made by plants is used by plants and animals as a source of energy. To release the energy
contained in the bonds of glucose, the glucose must be converted to ATP. The process by which ATP is made from
glucose is called cellular respiration. Respiration also produces waste products including carbon dioxide and water, which
are the same substances that served as raw materials for photosynthesis. In water, carbon dioxide dissolves to form a
weak acid. As a result, an acid-base indicator such as bromothymol blue can be used to indicate the presence of carbon
dioxide. In this laboratory investigation, you will use bromothymol blue to explore the relationship between
photosynthesis and respiration.
MATERIALS [per team @ stations]
2 large test tubes
100 mL beaker
bromothymol blue indicator
permanent marker
MATERIALS [front cart]
parafilm - cover test tubes
2 sprigs water plant [anacharis]
drinking straw
PROCEDURE –
___1-Using marker label test tubes: D [dark] / L [light] and hour #
___2-Add 30 drops of bromothymol blue to 50mL water in 100mL beaker.
Caution: bromothymol blue is a dye and can stain your hands and clothing.
___3-Insert one end of a drinking straw into the bromothymol solution.
___-Gently blow through the straw.
___-Keep blowing until there is a change in the appearance of the bromothymol blue indicator.
___-Record your observations in the data table.
___4-Place a 5cm sprig of plant into both test tubes.
___5-Fill both test tubes 2/3 full with bromothymol solution.
___7-Place test tube L under bright light / test tube D in dark for 24 hours.
--------------___8-After 24 hours, examine each test tube.
___-Note any change in the appearance of the bromothymol blue indicator.
___-Record your observations in the data table.
PRELAB: IDENTIFY VARIABLES/ CONTROLS:
IV-INDEPENDENT VARIABLE: ______________________________________________________
DV-DEPENDENT VARIABLE: ______________________________________________________
CONTROL:
CONSTANTS:
______________________________________________________
-____________________________
-____________________________
-____________________________
-____________________________
PREDICT what will happen in each test tube:
Light: ________________________________________________________________________________
Dark: ________________________________________________________________________________
DATA:
____________________________________________________________
TEST
TUBES
LIGHT
INITIAL
AFTER 24 hours
DARK
RESULTS
QUALITATIVE: Explain in your own words what happened in the lab.
CONCLUSION: (1-3 bulleted statements each)
@ times the conclusion section will be ASSIGNED QUESTIONS
1- EXPLAIN why bromothymol blue was used in this experiment.
2-EXPLAIN why the bromothymol blue indicator changed color after blowing into the cups
3- IDENTIFY the purpose of placing the anacharis plant in test tubes
4-ANALYZE why differences were observed between the plant in the light and the plant in the dark
5-EXPLAIN the process of photosynthesis
6-IDENTIFY how the results demonstrate the requirements necessary for this process to occur
7-PROPOSE possible future applications and adaptations
GOING FURTHER
BACKGROUND:
Photosynthesis requires light energy to proceed, but most plants are not in the sun 24 hours a day.
What reactions are taking place during the night?
Consider the following experiment to help you answer the questions below.
You have two sealed boxes.
One is clear with a light source shining into it, and the other is completely dark.
In each box is placed a healthy, genetically identical plant with no know disorders or diseases.
Both plants have access to adequate water and nutrients.
At the end of one week, both plants are still alive, but one is clearly doing better than the other.
ANALYZE:
1-IDENTIFY the INPUTs required for photosynthesis?
2-IDENTIFY the INPUTs required for cellular respiration?
3.
What are the outputs of photosynthesis?
4.
What are the outputs of cellular respiration?
5.
After one week in the box, which plant will be healthier and why?
6.
Why are BOTH plants still alive
7.
Which gases will increase in each box?
8.
Which gases will decrease in each box?
9.
In which box is the Calvin Cycle taking place?
10.
In which box is cellular respiration taking place?
11.
What is the independent variable?
12.
What is the dependant variable?
13.
What are 3 constants?