Osmosis is the movement of water and is always the movement in the membrane. Diffusion is the movement of molecules
Motor neurons carry impulses to the effectors in the body, which are the muscles or glands that produce a change based on a stimulus sensed by the receptors. The motor neurons "innervate" muscle fibers, which essentially means that they cause them to move. The fewer the muscle fibers associated with a motor neuron, the more precise are the movements of those fibers. Having to control a small number of fibers, the neuron is able to coordinate more dexterous motions. An example of a region where there are not a lot of muscle fibers related to each neuron is in your fingers.
<span>Males and females are attracted to each other in order to ensure the viability and fertility of the offspring, which is also why it is uncommon that males of one species be attracted to females of another. Members of two different species cannot mate and thus cannot produce fertile, viable offspring, unless they are part of different sub-species. But they must be part of the same species.
</span>
If in an eight-cell embryo of an organism, the cells of the upper tier are aligned over the cells of the lower tier at a slight angle, it is likely that the organism is a vertebrate.
<span />
