some discussion questions from general bio class, help plz! I cannot seperate th
ID: 37618 • Letter: S
Question
some discussion questions from general bio class, help plz! I cannot seperate these questions since up to limit. Any tips will be much helpful! Thank u
1. If species are constantly evolving by adapting to changing environments, then why would most biologists agree that evolution can never produce a perfectly adapted species?
2. What is the biological basis for assigning all human populations to a single species? Explain why it is unlikely that a second human species could arise in the future.
3. Why might hybrids, a species formed from two different species, be of interest to evolutionary biologists? How might your answer relate to the fact that some hybrids are viable and fertile while others are not?
4. what is evolution and how it works, du you think the human race is still evolving? If so, in what specific way?
5. Most scientists today agree that life on Earth can arise only from preexisting life and yet these same scientists believe that life on Earth began by spontaneous generation. Are they contradicting themselves? Explain.
Explanation / Answer
Answer:
1) We tend to assume that all characteristics of species are adaptations that have arisen through natural selection. Many are neither adaptations nor the result of selection at all.
2)The biological basis for assigning all human populations to a single species is the simple fact that they all can, and do, interbreed quite readily.
For cladogenesis to occur in a large primate species like humans, this would most likely require complete genetic isolation, for tens of thousands of generations (hundreds of thousands of years) at a *minimum*.
It not clear why extinctions opening up ecological niches would help. In a lot of organisms, this does produce additional ways for cladogenesis to occur besides geographical isolation ... i.e. members of a species will occupy different niches in the same geographical region (e.g. one coming out at night, the other during the day) and this can lead to speciation. But as humans are so flexible as far as expanding into multiple niches simultaneously, I don't see this happening to such a degree as to spin off a new human species.
3)a hybrid is an offspring of two animals or plants of different breeds, varieties, species or genera.
In general usage, hybrid is synonymous with heterozygous: any offspring resulting from the breeding of two genetically distinct individuals, a genetic hybrid carries two different alleles of the same gene, a structural hybrid results from the fusion of gametes that have differing structure in at least one chromosome, as a result ofstructural abnormalities, a numerical hybrid results from the fusion of gametes having different haploid numbers of chromosomes, a permanent hybrid is a situation where only the heterozygous genotype occurs, because all homozygous combinations are lethal.
4)
Evolution is well supported by many examples of changes in various species leading to the diversity of life seen today.Evolution occurs in response to outside forces that weed out whatever individuals are least fit to survive those pressures, allowing those better-fit individuals to survive and reproduce. However, since humans radically alter their environments, some researchers have questioned whether natural forces of selection continue to act upon our species.
The researchers investigated how agriculture might have affected four key aspects of human life
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