Ap bio write up

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Question:
Why would sensing and responding to vinegar be important to an organism?
-It could train them to respond to certain smells and respond in a certain way.

How would natural selection affect an organism’s ability to sense and respond to this stimulus?
-The organism depends on its ability to sense and respond. The organisms could compete for water or hydration.

What other types of stimuli would be important for the organism to respond to?
- An organism that is used to light is suddenly put in darkness, it may search for light. If an organism that is used to darkness is suddenly put into light, it may search for darkness.

Research:

Organisms orient to certain stimuli that are important to their survival. Movement toward or away from important stimuli depends upon both the sensory and motor abilities of the organism. An organism that senses an optimal food source will usually rely on smell. The movement toward the food source would be called a positive chemotaxi.

Behavior can be either innate or learned. Innate behavior is instinct and inherited. Learned behaviors are not inherited and can be changed as a result of the animal’s experience with its environment and the other organisms it interacts with.

Hypothesis:
The pill bugs will move away from the vinegar and have a positive chemotaxi to the water.

Experiment/Procedure:
The experiment involves observing the behaviors of pill bugs.

The materials needed are a behavior tray, plexi glass, pill bugs, cotton ball, vinegar, and water. The procedure is as follows: Label each chamber of the behavior tray A, B, C ,D, and E. Place a drop or two of vinegar on a cotton ball and place it in chamber A. Place a drop or two of water on another cotton ball and place it in chamber D. Place a total of ten organisms in the behavior tray; two in each chamber. Cover the tray with plexi glass and observe the specimens for ten minutes. Count the organisms in each chamber every minute and record the observations.

Data:
Time (min)
Organisms in chamber A
Organisms in chamber B
Organisms in chamber C
Organisms in chamber D
Organisms in chamber E
0
2
2
2
2
2
1
2
3
1
3
1
2
2
2
3
2
0
3
3
0
3
2
1
4
5
2
0
2
0
5
7
0
1
2
0
6
4
1
0
2
3
7
5
0
0
3
1
8
3
2
0
4
0
9
4
2
2
2
1
10
3
1
4
1
1
Ave.
3.8
1.3
1.4
2.3
0.8

A
B
C
D
E
O
3.8
1.3
1.4
2.3
0.8
E
2
2
2
2
2
O-E
1.8
-0.7
-0.6
0.3
-1.2
(O-E)2
3.24
0.49
0.36
0.09
1.44
(O-E)2/E
1.62
0.245
0.18
.045
0.72
X2= 2.81

Analysis:
Question 1: Were there positive or negative chemotaxis?
-There was a positive chemotaxi towards the vinegar

Question 2: What uncontrolled sensory factors may have affected results? How might you control for those factors? -Light/dark: You could have made sure there was equal lighting in all chambers or made some chambers darker than others.

Conclusions:
My hypothesis was incorrect. I expected the bugs to move away from the vinegar, but instead they seemed to move towards it.

Sources of Error:

One source of error in this experiment was one bug not being accounted for sometimes because he was hidden under the cotton ball.
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