Photosynthesis and Respiration Radish Germination Experiment

Photosynthesis and Respiration: Radish Germination Experiment

Experimental design

A. Three 1.5 g batches of radish seeds are weighed and place on a paper towel in a petri dish and exposed to the following conditions.

Treatment 1. Seeds placed on DRY paper towels in LIGHT

Treatment 2. Seeds placed on WET paper towels in LIGHT

Treatment 3. Seeds placed on WET paper towels in DARK

B. After 1 week, the plant material for each treatment was dried in an oven overnight (no water left). The weight was recorded as plant biomass (in grams).

Your prediction. DO NOT LOOK AT THE DATA AT TOP OF THE NEXT PAGE. Will the biomass increase, decrease or remain the same? Why?

Treatment

Prediction

Reasoning

1 (dry/light)

2 (wet/light)

3 (wet/dark)

Results. After the one week exposure and after drying, the biomasses were recorded as:

Treatment

Beginning biomass (g)

Ending biomass (g)

Change in mass (g)

1

1.5

1.46

2

1.5

1.63

3

1.5

1.20

1. What does the change in biomass (increase or decrease) mean?

2. What might have been the contribution of light to the biomass change?

3. What might have been the contribution of water to the biomass change?

4. What else might contribute to the gain in mass in the light + water condition?

5. What would have happened if the seeds had been placed in a wet/light, oxygen-free, pure CO₂environment? Explain in two sentences.

6. What would have happened if the seeds had been placed in a wet/light, CO₂ -free, pure oxygen environment? Explain in two sentences.

Solution

1. The change in biomass means increase in treatment 2 and decrease in treatments in 1 and 3.

2. Light contributed to gain the biomass because of germination of seeds have been occurred in presence of light.

3. Water is providing the oxygen and other minerals in minute traces that are absorbed by seeds to germinate and gain biomass. Oxygen necessary for the metabolic activities in seedling during germination.

4. The germinating seeds in presence of light and water synthesize food materials through photosynthesis and gain in biomass.

5. The seeds when kept in oxygen free or pure CO₂ environment the seeds cannot germinate. This is because excess CO₂ is toxic to germinating seeds.

6. When the seeds are planted in light and oxygen, the seeds able to germinate due to photosynthesis and O₂ helps tooxidation of synthesized food material to provide energy in the form of ATP. This energy helps the seeds to germinate and further growth and development of seeds into plant.