Answer and Explanation:
Due to technical problems, you will find the complete answer and explanation in the attached files
I think the hydra lacks the specialized cells for touch and chemical detection. On the other hand earthworms have touch, light, vibration and chemical receptors along the entire body surface. Both of them are invertebrates (those animals without a backbone), they include insects, worms, jelly fish, spiders among other animals.
Just think about cancer.. it's uncontrolled cell growth, so mutations in genes can cause cancer by accelerating cell division. As the cells contribute to grow they then develop as a tumor.
Answer:
R = 480 Ohm
Yes, the current is steady since the power supply is a constant 12V (comming from the battery).
Explanation:
U=I*R
R = U / I
U = 12 V
I = 0.025 A
R = 12 / 0.025
R = 480 Ohm
