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.
Answer:
The steps that can be seen in this story are observation and the questioning phase, which can also be called elaboration of the problem.
Explanation:
The scientific method is a set of phases that are able to guide researchers to the creation of scientific knowledge, through an experiment. This method is essential for conducting scientific research, allowing an experiment to be managed in a way that promotes answers to scientists' questions. The scientific method presents the phases called observation, questioning (or elaboration of the problem), elaboration of hypotheses, experimentation, analysis of the results and conclusion.
In the story shown in the question above, we can see the phases called observation and questioning. The observation takes place the moment Fleming noticed a fungus capable of growing on colonies of bacteria that cause throat infections, killing them. This observation made him enter the questioning phase, when he wondered if the fungus was able to prevent the growth of these bacteria.
Answer:
Option D- frequency of the heterozygous qenotype
Explanation:
In the Hardy-Weinberg equilibrium , 2pq stands for the genotype frequency of heterozygotes (Aa) in a population at the state of equilibrium. dominant homozygotes (AA) is represented by the p-square and q- square represents the recessive homozygotes (aa) frequency. p represents the allele frequency of A Allele and q stands for the allele frequency of the allele a. Summation of the terms gives an equal to 1(100%). The sum of all of these terms is always equal to due to the fact that the 3 frequencies in the equation are the available or possible allele combinations.
Hardy-Weinberg is relevant for it helps us in comparison of a population's actual genetic structure as time goes on along with the genetic structure we are to get if really population was in Hardy-Weinberg equilibrium state that is population was not evolving.
Photosynthesis.. hope I helped (:
