It's some change in the conditions around the organism, which the organism can detect and respond to. A change in temperature, more light, or something physically poking the organism are examples.
Most of it follows its cycle, going back to the atmosphere.
The image below, shows you how the nitrogen cycle is.
Hope it helped,
Happy homework/ study/ exam!
<span>The answer is a certain required chemicals must be actively
transported. Blood brain barrier is a
selective membrane that separates blood circulating from the brain and the
fluid of extracellular in the central nervous system. This is also called a
filtering mechanism, the capillaries that carry blood to the brain and spinal
cord tissue blocking the path way of the certain substance.</span>
the total number of pushes all together will be <u>8</u><u>N</u>
Answer:
The answer is False. Although sensitive cells are <u>more abundant</u> in the <u>anterior portion</u> of the annelid´s body, in general, they are arranged in all the segments.
Explanation:
Annelids, such as the earthworm, have a variety of sensory cells:
- <u>Mechanoreceptors</u>, disposed of in groups in <em><u>each segment</u></em> of their body.
- <u>Photoreceptors</u>: Light-sensitive cells. Although they are <em><u>located in the whole </u></em>body, they are <em><u>abundant in anterior and posterior segments</u></em>, concentrated in the intern and dorsal part of the epidermis.
- <u>Humidity receptors</u> are the most sensitive cells and are <u>located in the first segments</u> of the earthworm body
- <u>Chemoreceptors</u>: sensorial cells cumulus forming a prominent tubercle with prolongations that extends through the cuticle. These tubercles form three rings <em><u>in each segment</u></em> but are especially <em><u>abundant in the anterior part</u></em> of the body.
The tegument is very rich in free nervous terminations, which functions might be tactile.