What is the difference between phototropism , gravitropism , hydrotropism , and thigmotropism

Geo- means earth, tropism is movement. Geotropism is what makes roots grow toward gravity and shoots grow away from gravity, so that plants are oriented correctly in the ground.

The response of plants or animals towards light is called phototropism.

When the response is towards the light, it is called positive phototropism.

And when the response is away from the source of light, it is called negative phototropism.

For example, we see plants bending towards sunlight. It is actually their response towards light and is called positive phototropism.

Thigmotropism is the directional response of a plant organ to touch or physical contact with a solid object. This directional response is generally caused by the induction of some pattern of differential growth. This phenomenon is clearly illustrated by the climbing tendrils of some plants, such as the sweet pea

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.