all cells look the same.
rest of the options are a part of the cell theory.
Examples:
Respiratory System, (I think) Organ System, Circulatory System, Nervous System, etc.
Answer: The most reason was that cell-to-cell communication and the different chemical compositions of the cell walls of plant, fungi, and bacteria restricts the intercellular communication to their own species.
Explanation:
Density of the animal population Animal population is the only biotic or living factor. Grazing by herbivores, like sea turtles, will affect seagrass populations. Too many herbivores, not enough segrass.
Answer:
The correct answer is B. A small substance generated in response to receptor binding that activate or inactivate specific proteins.
Explanation:
An example of second messengers are AMPcyclic, Ca2 + ion. In the case of cAMP, the enzyme adenylate cyclase is synthesized from ATP (this is found within the cell membrane). The AMPC is involved in cell signal transduction pathways before external and / or internal stimuli, (example: adrenaline hormone), being able to activate the enzyme called protein kinase A (PKA), which phosphorylates its target and thus the signal is transmitted.