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AP Plant Responses Lab
Part A – Seed responses
a. Soak 4 pea seeds in water overnight.
b. Put enough layers of dampened paper towel pieces into a Petri dish base to fill it about ¾ full.
c. Place the soaked pea seeds onto the filter paper in a circular pattern with the hilium of each seed facing the outside of the Petri dish as shown below:
d. Tape the dish shut. It should be tight enough that the pea seeds are pressed firmly into the paper, if not, add more paper towel pieces before taping. Label it with your group members names.
e. Position the dish as vertical as possible without disturbing the seeds. Allow to grow for 3-4 days.
1. Draw a picture of the root growth of each of the seeds after 3 days in the space below.
2. Now we will turn the dish 180 degrees and let it sit vertically for another 3-4 days. What do you predict will happen to the direction of the root and shoot growth?
3. What actually happened?
4. What type of tropism is demonstrated by the seed root growth? (Hint: this is not as a result of light)
5. Explain how the seed root “knows” to grow in this direction. (Include the name of the hormone and other structures involved and what each one does)
6. What type of tropism is demonstrated by the seed shoot growth? (Hint: this is not as a result of light)
7. Explain how the seed shoot “knows” to grow in this direction. (Include the name of the hormone and other structures involved and what each one does)
Part B – Oat response to light
A. Soak several oat seeds in warm water for 35-45 minutes.
B. Place 10-12 seeds in a pot of vermiculite and cover with an additional 2-3 mm of vermiculite. Water well and place in a dark place for about 5 days, until the oat seedlings have reached 4-5 cm high.
C. Cut the tips off of 3 seedlings. Cover the tips of 3 seedlings with a cap of aluminum foil (be sure no light reaches the tips) and leave 3 seedlings alone.
D. Place all of the seedlings under a box with one slit for light to enter from one side. Allow to grow for 2-3 days. Make observations.
1. At the end of the experiment, what did you notice about the growth of the seedlings that were left unchanged?
2. Why did they do this? (Include the name of the hormone and other structures involved and what each one does)
3. At the end of the experiment, what did you notice about the growth of the seedlings that had their tips cut off?
4. Why did they do this?
5. At the end of the experiment, what did you notice about the growth of the seedlings that had their tips covered?
6. Why did they do this?
Part C – Seedling response to an obstacle
a. Soak 4 pea seeds in water overnight.
b. Put enough layers of dampened paper towel pieces into a Petri dish base to fill it about ¾ full. Put 1 filter paper circle on top.
c. Place the soaked pea seeds onto the filter paper in a circular pattern with the hilium of each seed facing downward in the Petri dish.
d. Place a barrier above each seed in the Petri dish.
e. Tape the dish shut. It should be tight enough that the pea seeds are pressed firmly into the paper, if not, add more paper towel pieces before taping. Label it with your group members names. Allow to grow for 5-7 days.
1. Draw a picture of how the shoot responded to the barrier.
2. Explain how the seed shoot “knows” to grow in this way. (Include the name of the hormone and other structures involved and what each one does) (Hint: This is not the same as the previous parts – deal just with the barrier aspect of it)