Pattern of reactions of Amoeba to light variations is

Options

A. negative to bright and positive to dim light.
B. positive to bright light
C. negative to dim light
D. negative to both bright and dim lights

Answer

To answer the question regarding the pattern of reactions of Amoeba to light variations, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Amoeba**:
- Amoeba is a unicellular organism that lacks specialized structures but has various organelles. It moves using extensions called pseudopods.

2. **Amoeboid Movement**:
- The movement of Amoeba is referred to as amoeboid movement, which occurs through the formation and retraction of pseudopods. This movement is facilitated by the transformation between the outer gel-like cytoplasm (plasma gel) and the inner less viscous cytoplasm (plasma sol).

3. **Response to Light**:
- Amoeba responds to light stimuli. When exposed to light, chemical changes occur within the organism that affect its movement and orientation.

4. **Observations on Light Intensity**:
- Studies indicate that when the intensity of light is constant, the amoeba may show some movement after a while. However, if the light intensity is increased sharply, the movement stops, indicating a negative response to bright light.

5. **Positive Response to Dim Light**:
- In contrast, under dim light conditions, Amoeba exhibits movement, indicating a positive response to lower light intensity.

6. **Conclusion**:
- Based on these observations, we can conclude that Amoeba shows a negative response to bright light (movement stops) and a positive response to dim light (movement continues).

7. **Answer Selection**:
- Among the provided options:
- Option 1: Negative to bright light and positive to dim light (Correct)
- Option 2: Positive to bright light, negative to dim light (Incorrect)
- Option 3: Negative to both bright and dim light (Incorrect)

Thus, the correct answer is **Option 1: Negative to bright light and positive to dim light**.