Biology: Lab report Germination
Biology Lab Report
Seed Germination
By: John Abarshi
(Figure One: Cress Seed Germination)
Introduction
This term, we embarked upon our first biology experiment. Recently, in class, we have been learning about plant reproduction. Amongst the vast amount of information pertaining to the topic of plant reproduction is germination. Germination is the process of sprouting, whereby seeds or spores sprout or emerge and begin to grow. [1] [2] When a seed is germinating, certain factors affect its germination. It was our task to come up with two variables that could influence seed germination and to investigate this. After much contemplation and consideration, I managed to pinprick what factors I would like to investigate. I will thus investigate if altering the light and temperature of the cress seeds' environment will affect the germination.
Research Question
How do light and temperature affect the germination of a cress seed?
Hypothesis
If cress seeds are placed in a dark environment, then their germination will be negatively affected compared to cress seeds grown in a normal light environment because seeds
If cress seeds are placed in an environment with excessive exposure to light, then their germination will be positively affected compared to cress seeds grown in a normal light environment because seeds
If cress seeds are placed in a cold environment, then their germination will be negatively affected compared to cress seeds grown in a normal light environment because seeds
If cress seeds are placed in a hot environment, then their germination will be positively affected compared to cress seeds grown in a normal light environment because seeds
Variables
The independent variables in this experiment were the light and the temperature. We put some of the cress seeds under a bright light and others in a dark cupboard. As for the temperature, we put some cress seeds in a stove and others in a fridge.
The dependent variable in this experiment is the germination. The speed and general process will differ depending on the independent variables.
The controlled variables were the type of seeds and the water. Different seeds obviously germinate at different paces and watering the seeds with different liquids may affect the germination, so to ensure a fair test I want to keep the type of seeds the same.
Materials
Glassware
Substances
Safety Equipment
Miscellaneous
Measuring Cylinder
Water
Safety Coat
Stove
Petri dish x6
Cress seeds x180
Refrigerator
Cotton wool
Cupboard
Lamp
Labels x6
Method
. Prepare the area where you will be carrying out your experiment. This entails collecting all the necessary materials and ensuring that you are wearing the adequate safety equipment. Do not forget to label each of the Petri dishes so as not to get confused later.
2. Cover the bottom ...
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Materials
Glassware
Substances
Safety Equipment
Miscellaneous
Measuring Cylinder
Water
Safety Coat
Stove
Petri dish x6
Cress seeds x180
Refrigerator
Cotton wool
Cupboard
Lamp
Labels x6
Method
. Prepare the area where you will be carrying out your experiment. This entails collecting all the necessary materials and ensuring that you are wearing the adequate safety equipment. Do not forget to label each of the Petri dishes so as not to get confused later.
2. Cover the bottom of the Petri dish with a layer of cotton wool.
3. Sprinkle thirty cress seeds in the Petri dish, on the cotton wool. Water until cotton wool is drenched.
4. Put the lid on. Repeat this for the remaining three Petri dishes.
5. Place on dish in a stove, one in a refrigerator, one in a dark cupboard, and one under a bright lamp.
6. Water all seeds regularly.
Control Experiment
This is the method for the control experiment. We chose to make two control experiments. We decided this because we could each monitor one of them and it would also offer additional reliability.
. Cover the bottom of the Petri dish with a layer of cotton wool.
2. Sprinkle thirty cress seeds in the Petri dish, on the cotton wool. Water until cotton wool is drenched.
3. Put the lid on. Repeat this for the remaining Petri dish.
4. Place both of the dishes in a regular environment. This means a place with an average room temperature and without extreme light conditions.
Observations
Day 1
Day 2
Light
Dark
Warm
Cold
Control 1
Control 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Control 1
Control 2
Light
Dark
Warm
Cold
Day 1
No germination yet
No germination yet
No germination yet
No germination yet
No germination yet
No germination yet
Day 2
Seeds have formed a mucus membrane
Seeds have formed a mucus membrane
Seeds have formed a mucus membrane
Seeds have formed a mucus membrane
Seeds have formed a mucus membrane
Seeds have formed a mucus membrane
Day 3
Small shoots have sprouted
Small shoots have sprouted
Small shoots have sprouted
Small shoots have sprouted
Relatively large shoots have sprouted
Same as Day 2
Day 4
Dark green leaves have formed at the end of the shoots, shoots are growing very quickly
No leaves yet, only continued growth of shoots
Little leaves have formed at the end of the shoots
Little yellow leaves have formed at the end of the shoots
Green leaves have formed at the end of ever-growing shoots
Same as Day 2
Day 5
Some of the shoots are taller than others, there is quite a large difference
They are not standing erect, and there is a large difference of sizes among the seeds
Shoots are now standing erect with dark green leaves
Yellow leaves have formed and the shoots stand erect
Shoots are erect and are still growing
Same as Day 2
Day 6
Same as Day 5 but longer
All seeds have by now germinated, they are standing erect and tall
Same as Day 5 but longer
All seeds have germinated and are sporting long yellow leaved plants
Plants have grown enormously and are no longer standing erect
Same as Day 2
Day 7
Same as Day 6 but longer yet. All seeds have germinated.
Same as Day 6 but a tad longer
Same as Day 6 but longer
Same as Day 6 but longer
The plans have kept on growing but are still no longer erect
Same as Day 2
Day 8
Same as Day 7 but longer, stems are white
Same as Day 7 but longer and the stems are green
White stems, same as Day 7 but longer
White stems, same as Day 7 but longer
The plants have stopped growing and are the same as Day 7
Same as Day 2
Results in cm, showing average growth of plants
Control 1
Control 2
Light
Dark
Warm
Cold
Day 1
n/a
n/a
n/a
n/a
n/a
n/a
Day 2
n/a
n/a
n/a
n/a
n/a
n/a
Day 3
0.5
0.4
0.7
0.7
.5
n/a
Day 4
.2
.3
2.5
n/a
Day 5
2.4
2.2
2.6
2.3
4
n/a
Day 6
3.8
3.7
4
3.7
5.2
n/a
Day 7
4.4
4.6
4.9
4.5
6.4
n/a
Day 8
5.6
5.9
5.8
5.7
6.4
n/a
Data Manipulation
Analysis of Graph One
In this graph we can clearly see what happened to the seeds. It is obvious that the seeds in a hot environment grew the fastest and perhaps the best. In the graph, one can also see that the cress seeds in a hot environment perhaps reached their limit. I can recollect this from the graph because the very last part of the blue line does not escalate anymore; it is a straight horizontal line. The control seeds fluctuated a bit in the beginning but the overall pattern is steadily upwards. The seeds in a cold environment did not even germinate. This can be collected from the graph due to the lack of a slope in the red line.
Analysis of Graph Two
The results of this experiment are a lot closer than the ones shown in the first graph. The seeds that germinated in the light grew faster and a bit taller than the other two. This is evident because the blue line has a steeper slope than the red and green line. The seeds that germinated in the dark grew practically as fast and tall as the control seeds. This can be collected from the graph because of the proximity of the red an green line, the lines sometimes overlap.
Discussion
Conclusion
Light Experiment
I will conclude each experiment separately as they were, in fact, separate experiments. Upon testing the variable of light, it has become apparent that seeds germinate more quickly in the light. My hypothesis on this was correct. Although the difference is small, the seeds that germinated in the dark grew slightly slower than the control experiment. In answer to my research question, seeds placed in light will grow faster. Although a seed can germinate in the dark, once it has germinated it needs light. It is necessary because plants need photosynthesis to convert water and carbon dioxide into sugar, which is food for a plant. [3]
Temperature Experiment
Upon testing the variable of temperature, it has become clear that cress seeds germinate much more quickly in a warmer climate. My hypothesis was thus correct. There is a massive difference between the seeds placed in cold and the seeds placed in heat. The ones placed in the cold did not even germinate. In answer to my research question, temperature does affect germination. When placed in heat, cress seeds will germinate much more quickly. Temperature affects growth rates because it affects the cellular metabolic. Temperatures in which seeds will germinate vary greatly. The cress seeds that remained in the cold, stayed dormant and the heat alleviated that dormancy. [4]
Evaluation
I believe that my results are quite reliable. All controlled variables were kept controlled and so an unfair test would be unusual. If I were to carry out this experiment again, I would end up with the same results. That is how I know it is reliable. Another factor that ensures reliability is that multiple cress seeds were planted so it could not just have been a fluke. For these reasons, I believe that my results are reliable.
I also believe that my results are quite valid. It is not as if the reason for some of my plants growing faster than others is reliant on something else. The results are well grounded in the logic of plant germination. It is justifiable with an adequate scientific explanation and thus I believe my results are valid to the fullest extent.
Naturally, there are improvements that could be made to the experiment. If I were to execute this experiment again, I would monitor the seeds more often. Sometimes when I would come back to my seeds the next day, they would look enormously different to the day before. In the time in between these two steps, a lot could have happened. In this way, I feel that I have missed out on some crucial steps. Other than that, I am quite pleased with my results and the overall experiment. I have learned a lot throughout the entire process.
Works Cited
[1] (Figure One) "The Seed Biology Place - Endosperm Weakening." The Seed Biology Place - The Seed Biology Place. 12 Mar. 2005. Web. 23 Nov. 2010. <http://www.seedbiology.de/weakening.asp>.
[2] "Germination | Define Germination at Dictionary.com." Dictionary.com | Find the Meanings and Definitions of Words at Dictionary.com. Web. 23 Nov. 2010. <http://dictionary.reference.com/browse/germination>.
[3] "Germination." Wikipedia, the Free Encyclopedia. Web. 23 Nov. 2010. <http://en.wikipedia.org/wiki/Germination#Requirements_for_seed_germination>.
[4] "What Do My Seed Need for Good Germination?" Where Seed Starting Success Begins! Web. 23 Nov. 2010. <http://www.successwithseed.org/getting-started/368-what-do-my-seed-need-for-good-germination>.
[5] "Germination." Wikipedia, the Free Encyclopedia. Wikipedia. Web. 23 Nov. 2010. <http://en.wikipedia.org/wiki/Germination>.
John Abarshi It10 November 21, 2010
