<h2>540 million years ago
</h2>
Paleozoic.
Era immediately follows Precambrian It lasted about 4.5 billion years.
When did abundant fossil evidence first appear in the geologic record.
540 million years ago.
Darwin lived in a time where natural selection was a strange theory among scientists and researchers. This was especially true when other researcher Lamarck argued that organisms passed on helpful traits to their offspring, that they magically could form a new trait to adapt to their environment and then pass it onto their offspring. For example, if a giraffe was too short to reach food, it would grow a larger neck in its lifetime and then pass that trait onto its offspring. Darwin argued that, through the process of survival of the fittest, that short giraffe would die off and never receive the chance to pass on its shortness to future populations. Thus, taller giraffes would survive— they can reach food, shorter giraffes can’t— and the short genes would disappear. The fact that Darwin was introducing a new theory that nobody was used to at the time was peculiar, so he had few people on his side until long after his observations.
Another problem Darwin had was the lack of technology. To travel, Darwin would have to use boats to reach far away places, and of course, this took time.
The final problem Darwin had was the extra time it took for evolution, a process that can take up to millions of years. Evolution didn’t occur over night— it took time for Darwin to conduct experiments, observe, conduct them again, come to a conclusion, and so on.
Hope this helped a little!
Complete question:
Question: When crossing two individuals, the offspring display only one of the two traits found in parents. Which principle of Mendelian genetics is supported by this observation?
a) segregation
b) independent assortment
c) dominance and recessiveness
d) allele frequency
Answer:
c) dominance and recessiveness
Explanation:
According to Mendel's principle of dominance and recessiveness, the alleles of one gene may be dominant or recessive in nature. When present together, only the dominant allele is able to express itself. Therefore, a hybrid individual for a gene would express only the dominant phenotype. In the given cross, the progeny express only one of the two traits found in the parents. This means that the progeny is heterozygous for the trait and is expressing the dominant trait. The recessive trait is not expressed due to the presence of the allele for the dominant trait.
<span>Diminished breath sounds actually imply a reduction
or lack of air movement. In this case, anterior and posteriorsymmetric chest expansion should be examined to evaluate and compare
lung function. Tactile fremituspalpation, percussion, and voice sounds
auscultation should also be conducted because these tests reveal the density of
underlying tissue.</span>
