Answer:
The correct order is dehydration, embed in wax, cut into sections, staining
Explanation:
There are certain proceedings needed to obtain stained sections of vegetable or animal tissues for their microscope observations.
These steps are:
- Obtention of the material: The tissue is cut to an adequate size.
- Fixation: When tissues are extracted from the organism, they suffer autolysis and putrefaction, so they need to be fixated in order to keep their cells in the best state possible. Fixation involves preserving the original morphological and molecular characteristics of the tissue. Fixation avoids autolysis, putrefaction, distortion, and retraction of cells and the tissue that could affect its volume or morphology.
- Dehydration. Once fixated, the fixator must be eliminated and the tissue is dehydrated by using a gradual series of solutions with alcohol in ascendant concentrations. Dehydration must be gradual to avoid tissue deformation.
- Inclusion. To obtain thin cuts that can be observed under the optic microscope, the tissues must be included in a consistent, firm substance, that might be either hydrophilic or hydrophobic. A hydrophobic medium is paraffin wax, that provides hardness and plasticity.
- Cut. The tissue included in wax must be cut in slides or sections thin enough to allow the diffusion and penetration of light. A microtome is used to perform these cuts. When using paraffine for tissue inclusion, the cuts are about 5 to 20 micrometers of thickness.
- Stain. Once the cuts are performed, paraffin wax must be eliminated. This can be done by using an organic solvent. Then the tissue must be stained. Hematoxylin and Eosin are the most common dyes. Animal tissues in general do not have any natural color, so they need to be stained to be observed.
<span>organisms cannot adapt faster than rates of extinction</span>
Excitatory neurotransmitters cause the neuron to fire, and Inhibitory neurotransmitters cause the neuron not to fire.
Impulses are the signals passed from one neuron to another on the action of a stimulus. The impulses passed can be electrical or chemical. Neurotransmitters are the chemical molecules that help in the transfer of impulses between two neurons.
Chemicals like epinephrine, norepinephrine, and glutamate when released from the synaptic cleft of one neuron activate the receptors of other neurons, thereby initiating the other neuron to fire. These chemicals are called excitatory neurotransmitters.
Chemicals like GABA and glycine, when released from the synaptic cleft of one neuron do not activate the receptors of other neurons and hence the neurons will not fire the impulse. These chemicals are called inhibitory neurotransmitters.
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Biomes are typically defined<span> by their climate and dominant vegetation, including grassland, tundra, desert, tropical rainforest, and deciduous and coniferous forests.</span>
