Phototropism

Table 1 - Phototropism

Plant	Treatment	Response
A	normal overhead light	grows straight up
B	light from one side	grows toward light
C	plant on side, overhead light	grows toward light

1. Which plant is the control?

   A is control: normal overhead light, no special treatment.

2. Did the direction of the light source make a difference to the growth of the plant?

   Plant should grow toward light.

3. Did the stem of the plant exhibit positive or negative phototropism?

   Positive; stem should bend toward light.

4. Explain how this response is adaptive for the plant.

   Positive phototropism maximizes photosynthesis.

Thigmotropism

Hypothesis: If leaves are touched, then the leaflets will fold together.

If tip of leaf is touched, the rest of the leaflets close in sequence; this signal wave may travel to other groups of leaflets.

Table 2 - Thigmotropism in Mimosa

Stimulus Type	Response	Recovery Time
finger	fold	-
ice cube	fold	-
blow	fold?	-

Thigmotropism Graph p. 204

SKIP

Conclusion: Leaves respond to direct touch regardless of temperature.

1. Describe the plant's general response to touch.

   When leaves are touched, the leaflets fold, and the whole leaf droops.

2. Is the plant response to touch positive or negative for thigmotropism?

   Positive.

3. Was your hypothesis supported?
   Hopefully.

Phototaxis

SKIP

Chemotaxis p. 205

SKIP

Thigmotaxis p. 206

Hypothesis: If the planaria are touched at any point along its body, then it should move away from the stimulus.

Table 2 - Thigmotaxis in Planaria

Stimulus Type	Response
anterior	away?
pharynx	away?
posterior	away?

1. What is thigmotaxis?

   Thigmotaxis is movement toward or away from touch.

2. Do Planaria exhibit positive or negative thigmotaxis?

   Negative.

3. Was your hypothesis supported?

   Hopefully.

4. How might this behavior benefit the planaria?

   This helps the animal avoid predators.

Pupil

Table 6 - Pupil Reflex

Stimulus	Normal Light	Dark	Bright Light
Response in Size	medium	large	small

1. Explain the response that the pupil makes to varying amounts of light.

   Pupil size decreases when light increases.

2. Was the response automatic or did you have to think about performing it?

   Automatic.

3. Explain how this response is adaptive.

   This response allows the eye to adjust to different light conditions.

Blink p. 207

Table 7 - Blink Reflex

Stimulus	Response
Snap fingers	blink?
Cotton balls (wear goggles)	blink?

1. Does the subject always blink when the fingers are snapped?

   Perhaps not always, since the object is not moving toward the eye.
   Even with cotton balls thrown at the eyes, you can probably suppress blink reflex if eyes are protected by goggles.

2. If you were given the proper stimulus to blink do you think that you could suppress the response?

   Depends. Sometimes you should be able to suppress the response by focusing on something else or forcing muscles not to contract.

3. Explain how this response is adaptive.

   Blinking can prevent injury to eyes from flying objects.

Knee Jerk

Table 8 - Knee Jerk Reflex

Leg	Response
Left	jerk?
Right	jerk?

1. Was the response the same for both legs?

   Should be.

2. Was the response automatic or did you have to think about performing it?

   Automatic. But if you think about it, you can probably suppress the jerk by freezing your quadriceps muscles.

Hypothesis: If repeat the maze, then the subject will solve it faster.

Table 9 - Maze Learning

Trial Number	1	2	3	4	5	6	7	8	9	10
Seconds	99	89	69	72	59	30	22	20	12	15

p. 208 Graph for Maze Learning

Conclusion: I can learn upon repetition!

1. How many trials did it take for the subject to learn the maze?

   Hopefully less than 10.

2. Using the data and graph to support your answer, explain whether the learning happened gradually or abruptly?

   Probably gradually.

3. Was the hypothesis supported?

   Hopefully yes - we all have a brain and we should all be able to learn!