Answer:
1. Stabilizing Selection
2. Directional Selection
3. Disruptive Selection
Explanation:
Stabilizing Selection
This type of natural selection occurs when there are selective pressures working against two extremes of a trait and therefore the intermediate or “middle” trait is selected for. If we look at a distribution of traits in the population, it is noticeable that a standard distribution is followed:
Example: For a plant, the plants that are very tall are exposed to more wind and are at risk of being blown over. The plants that are very short fail to get enough sunlight to prosper. Therefore, the plants that are a middle height between the two get both enough sunlight and protection from the wind.
Directional Selection
This type of natural selection occurs when selective pressures are working in favour of one extreme of a trait. Therefore when looking at a distribution of traits in a population, a graph tends to lean more to one side:
Example: Giraffes with the longest necks are able to reach more leaves to each. Selective pressures will work in the advantage of the longer neck giraffes and therefore the distribution of the trait within the population will shift towards the longer neck trait.
Disruptive Selection
This type of natural selection occurs when selective pressures are working in favour of the two extremes and against the intermediate trait. This type of selection is not as common. When looking at a trait distribution, there are two higher peaks on both ends with a minimum in the middle as such:
Example: An area that has black, white and grey bunnies contains both black and white rocks. Both the traits for white and black will be favored by natural selection since they both prove useful for camouflage. The intermediate trait of grey does not prove as useful and therefore selective pressures act against the trait.
DNA is something everyone has in them to see
Answer:
b.Their cell walls have very different biochemical properties.
Explanation:
Cellulose is a homopolysaccharide of glucose residues and is the main chemical component of the cell walls of the plant cells. The glucose residues in cellulose are linked together by beta 1-4 glycosidic bonds. Chitin is a linear homopolysaccharide of glucose residues and is the main structural component of the fungal cell wall. On the other hand, peptidoglycan is the major structural component of the bacterial cell walls. Peptidoglycan is a heteropolysaccharide of two different residues. These are N-acetylglucosamine and N-acetylmuramic acid. Therefore, the chemical components and that make the cell walls in plants, fungi and bacteria differ significantly from each other imparting them distinct chemical features.
Answer: When using fossils approximate age by comparing it to similar rocks and fossils of known ages, is called relative dating.
Using that method we can determine the age of rock layers. That’s our way of dating them.
Hope this helps! ^^
