Please Help- Biology Questions!?

1. What are 2 traits OTHER then size %26amp; distribution of body hair that show Sexual Dimorphism in humans?

2. Why are mutations by themself NOT considered to be a significant contributor to changing gene frequencies in a population?

3. Why can genetic drift often lead to a reduction in genetic variation within a population?

4. What are 2 general structural features that Annelids %26amp; Arthropods have in common?

-------

1. Is genitilia one?

2. ? I think it's because mutation is a random process, so it doesn't occur frequent enough.

3.?? I don't understand how genetic drift leads to reduction if it's caused by sampling error...

4. ??

----------

Can someone please help me? My book doesn't explain this properly, it just give really long,confusing examples. I'm still searching for info online, but I haven't come across anything helpful yet.So I would really appreciate your help. Thank You! = )

Please Help- Biology Questions!?

1. Genitilia should be a good one, also pitch of voice, hip-waist ratio

2. The genetic code is redundant--as in a mutation may happen randomly, but chances are decent that it won't change the amino acid codon of the sequence even if it changes a base pair. To have an affect, the mutation must change an amino acid in a way that affects the protein shape %26amp; structure. The other factor is that most of the DNA is not actually coding, so assuming the mutation is equally likely to occur anywhere along the strand, there is a lot more room to miss than to hit coding DNA.

3. Genetic drift occurs when the population is suddenly reduced in number drastically, say a flood strands and isolates a few people on an island, so your are potentially losing a lot of variation because you're losing the allelic contribution of most of the population: you're limited to what is present in the few people who are left in your new, much smaller, population.

4. Both Annelids and Arthropods are segmented, and have coeloms (inner cavities)

Please Help- Biology Questions!?

I can help for 2 only.

2. Mutations aren't enough because often they will cause a premature death and be eliminated from evolution. So it will not change gene frequencies. As for mutations that do not cause a death, they often don't have an effect in the construction of proteins and not change a thing in the body, so we wouldn't notice it. Also, a mutation will take a lot of time before spreading out and actually causing a change in a big population's frequency. But it can eventually, that is how many animals became what they are and it explains the differences in species. Hope it clarified that at least

Please Help- Biology Questions!?

1. Genitals and hips

2. Diversity of a population. If you take away diversity and have a bottleneck then the mutations are more than likely to affect the whole population. However, because of the number of people and the amount of diversity mutations are not apparent. Remember mutations are not always bad sometimes mutations are a protective mechanism. Sickle Cell Anemia is a mutation that affects the ancestors of people who come from malaria stricken regions. This mutation allowed a better chance for survival. Though in North America we don't really have to worry much about that there is a region called the malaria belt in which this population would have a better chance of surviving infection than I would (I have Hispanic and white descendants).

3. Genetic Drift, - the bottle neck effect isolates a population. So lets say that you have a group of bears and the dominate gene is R for a red coat but. You have 50 black bears and 50 red bears eventually because they are isolated they will all have Red coats because the dominant gene chooses for Red. So eventually they all look the same. So there is a reduction in diversity do to a small population.

R + b = Rb is the genotype displays the Red phenotype

b + b = bb is the genotype displays the Black phenotype

R+ R= RR genotype displays the Red phenotype

Another added is that the bears are attracted to the red bears because they have a better sense of smell than the black bears.

This type of change might not happen immediately but, over years and eventually bb changes to Rb changes to RR. Reducing the amount of diversity because Rb + RR probability of equaling RR is 3:4.