Suzanne Distrola
AP Environmental
Pd: 2
Seed Germination
1. Discuss the germination rates and radical length of the lettuce seeds moistened in each of the
salt solutions.
If the salt solution percentage is too high, the seeds won’t grow, but most of the seeds grow
around 1% and 0.01% salt concentration.
2.
Looking at your data, do you notice any trends? Do any of your data not fit the trends you
observed? If so, explain why you think these data might lie outside the range you would expect.
The rates of growth of the seeds showed a trend. As the salt percentage grew, the rates grew,
then shrank, then grew, then shrank again. But when the concentrations reached 3%, no seeds
grew at all causing a flaw in the trend.
3. What do your results tell you about the salt toxicity on lettuce? What concentration is the LC50 ?
My results tell me that salt toxicity cannot be too high or the seeds won’t grow. The LC50
concentration is 0% through 3%.
4. If the precise LC50 was not apparent, what could you do to determine this number?
If the precise LC50 was not apparent, then you could determine this number or a number close to
it by analyzing your data and trends.
5. Given your knowledge of concentration gradients, draw a lettuce seed and, using arrows,
indicate the direction of the net movement of water as the lettuce seed rests in a hypertonic
(salt) solution. Draw a second lettuce seed, and indicate the direction of the net movement of
water in a hypotonic (salt) environment. Clearly label each drawing. Relate this to lettuce seed
germination and growth.
Salty Environment
Salt
6.
Water
Distilled environment
Salt
Water
Water
Water
The more salt that enters the seed, the less chance it has of growing, but if there is a correct
amount of water and salt, there is a greater chance of the seed growing.
6.
Write down any information you think is important that would help explain your results. Did
you expect to obtain the results you got? Did you have any problems doing the experiment? If
you were to do the experiment again, what would you do to make it better?
The percentage of salt solution is important to the growth of grass seeds, therefore, to much or
to little salt will affect your growth rates. I expected that the seeds would not grow due to the
minimal or maximum percentages of salt. Although, the experiment could have gone smoother.
The experiment went well, but could have been more organized.
7. Suppose you had to design a bioassay of a potentially toxic material with which you are not
familiar. How would you decide on the number and intervals of concentrations to test? How
would you determine the starting and final concentrations?
8. In view of the results of your bioassay, what can you say about salt applied to roads, and in the
environment?
Based on the results, one can infer that the salt applied to the roads could wash off and kill the
vegetation if there is enough salt. On the other hand, if the salt mixes with enough water, it
could lower the percentage of salt concentration and do less damage than plain salt.