Biology-2nd Semester Review-Part 1
Why is Natural variation so important?
So disease will not wipe out a population.
Choosing characters in offspring.
Blending mixing or breeding 2 organisms.
-Ex: If you want a really healthy dog, breed a mutt, not a purebred.
How can inbreeding cause health problems?
Purebreds share similar genetic make-up.
2 Causes of Gene Shuffling.
1-Chromosomes of homologous pairs move independently during meiosis.
2-Crossing over further increases number of different genotypes.
Do Mutations cause serious health problems?
2 diseases caused by minor mutations.
All genes and their different alleles in a population.
The number of times that allele occurs in the gene pool, compared to the number of times all other alleles for that same gene occur.
Single gene trait.
The process by which organisms with favorable variations reproduce at higher rates than those without such variations.
individuals with the average form of the trait has the highest fitness.
individuals with the more extreme form of a trait have a higher fitness than individuals with an average form.
individuals with either extreme variation of a trait have a higher fitness than those with the average form.
Survival of the Fittest
The more fit (adapted) the organism, the better chances they have to survive.
How do organism adapt to their environment?
Change food, grow hair, etc.
What causes adaptations?
Change of climate.
the gradual changes in gene frequencies in a population due to random events
By what means does genetic drift occur?
The Founder Effect
when few individuals begin a new isolated population
Why does the Founder's Effect occur most likely after a Natural Disaster?
The organisms could be seperated by the natural disaster, forcing the animals to adapt to their new environment.
Allele frequencies remain constant unless there are 1 or more factors.
5 conditions to maintain genetic equilbrium.
2-Very large population
3-no immigration or emmigration
5-No Natural Selection
The formation of a new species
3 types of reproductive isolation
2 populations are capable of interbreeding but do not understand each others courtship rituals.
Geographic barriers seperate populations.
2 or more species reproduce at different times.