A.
Tight junctions are <u>cell junctions in areas that are subjected to great mechanical stress, such as the skin and heart muscles</u>
Explanation:
They are also called <u>exclusion junctions</u>. This is because they form very tight junctions between adjacent cells such that only very small molecules, like ions, can pass in between the intercellular spaces of the cells. This is why they are found in regions where very little leakage is needed such as the heart -where blood could leak out during pumping- or the skin where foreign material cannot be allowed into the body.
They are also favorable in high stress regions because they bound cells together giving them structural integrity because they limit the movement of cells and their membrane intergral proteins.
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Answer:
The answer is A.
Explanation:
In the case of cyanide poisining which prevents the oxygen from being used by the body, the brain is one of the first organs that gets effected because it uses around 20% of the total oxygen intake of the body and the other systems and organs mostly depend on the brain to function properly so the brain runs out of oxygen before the other parts of the body.
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Answer:
Results in the evolution of the species: Directional selection
Results in new species: Disruptive selection
Favors traits at the two extremes: Disruptive selection
No increase in diversity: Directional selection
One extreme trait is favored: Directional selection
Diversity decreases: Stabilizing selection
Diversity increases: Disruptive selection
Explanation:
Directional selection which is also known as positive selection is known to be a mode of natural selection. In this type of selection, an extreme phenotype is favored over other phenotypes. This makes the allele frequency to move in the direction of that phenotype and this takes place over time.
Disruptive selection (known to be diversifying selection) talks about the certain changes in the population genetics whereby extreme values of a particular trait are favored over intermediate values. This results in new species.
While Stabilizing selection is a natural selection whereby there is a stabilization of the population mean on the particular value of a non-extreme trait. Here the diversity is decreases.
Answer;
The human eye contains more rods than cones photoreceptors.
Explanation;
-The retina of the human eye is the back part of the eye that contains the cells that respond to light. These specialized cells are called photoreceptors. There are 2 types of photoreceptors in the retina: rods and cones.
-The rods are most sensitive to light and dark changes, shape and movement and contain only one type of light-sensitive pigment. Rods are more numerous than cones in the periphery of the retina. The cones are not as sensitive to light as the rods. However, cones are most sensitive to one of three different colors (green, red or blue).
