Answer:
The fossil record helps paleontologists, archaeologists, and geologists place important events and species in the appropriate geologic era.
Explanation:
It is based on the Law of Superposition which states that in undisturbed rock sequences the bottom layers are older than the top layers.
Answer;
-The less dense, the more the ice will float, allowing animals to stay afloat and not in the water
Explanation;
-When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding. Solid water, or ice, is less dense than liquid water. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density.
-This means that ice floats on water and that lakes freeze from the top down to the bottom.This is vital for animals that live on ice, as their habitats would be greatly reduced or not exist at all if ice sank.
The statement water is easily polluted..... is true. Water is pretty much the world's best solvent. So even toxic substances are easily dissolved in it and when that happens they pollute the water.
Answer: Base pairs are formed when adenine forms a hydrogen bond with thymine, or cytosine forms a hydrogen bond with guanine. The second part of a nucleotide is the phosphate, which differentiates the nucleotide molecule from a nucleoside molecule.
Explanation:
Answer:
Selection is a directional process that leads to an increase or a decrease in the frequency of genes or genotypes. Selection is the process that increases the frequencies of plant resistance alleles in natural ecosystems through coevolution, and it is the process that increases the frequencies of virulence alleles in agricultural ecosystems during boom and bust cycles.
Selection occurs in response to a specific environmental factor. It is a central topic of population and evolutionary biology. The consequence of natural selection on the genetic structure and evolution of organisms is complicated. Natural selection can decrease the genetic variation in populations of organisms by selecting for or against a specific gene or gene combination (leading to directional selection). It can increase the genetic variation in populations by selecting for or against several genes or gene combinations (leading to disruptive selection or balancing selection). Natural selection might lead to speciation through the accumulation of adaptive genetic differences among reproductively isolated populations. Selection can also prevent speciation by homogenizing the population genetic structure across all locations.
Selection in plant pathology is mainly considered in the framework of gene-for-gene coevolution. Plant pathologists often think in terms of Van der Plank and his concept of "stabilizing selection" that would operate against pathogen strains with unnecessary virulence. As we will see shortly, Van der Plank used the wrong term, as he was actually referring to directional selection against unneeded virulence alleles.
