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IB 150 - Exam 3 With Complete Solutions Latest Update
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- IB 150
- Institution
- University Of Illinois - Urbana-Champaign
IB 150 - Exam 3 With Complete Solutions Latest Update
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Solution 2024/2025Pepper
IB 150 - Exam 3 With Complete Solutions
Latest Update
mutations ANS✔✔ genetic change that results in a slight variant in
genetic/DNA sequence (created new allele); adding one new allele doesn't
change overall frequency by very much - mild form of violating H-W; genetic
variation for any species results from this
genetic drift ANS✔✔ random changes in allele frequencies - change entirely
due to CHANCE; results from SAMPLING ERROR of which gametes produced
by the previous generation get fertilized and grow up to indiv. in next gen.;
more prevalent in SMALLER pop., the larger the associated sampling error -
GD plays a larger role in changing allele freq. b/t gen. in very small pops.
compared to large pops.; will modify allele freq. in FINITE pop. sizes - the
only way to completely avoid changes in allele freq. b/t pops. due to GD
would be to have an INFINITE pop. size - NOT POSSIBLE; Bottlenecks &
Founder Effects also inc. inbreeding; Random process by which biological
traits become either more or less common in a pop. due to sampling error
(chance) of which allele makes it to the next gen.
random sampling ANS✔✔ take small sample of much larger pop. of things -
it looks diff. than the entire pop. (has diff. allele frequencies compared to
large pop. - due to RANDOM CHANCE)
gene flow ANS✔✔ alleles entering and leaving pop. bc of migration
(immigration, emigration); start carrying some alleles that have become
more prevalent in one pop. to the other pop. w/ that allele that is not
prevalent at all; alleles of diff. genes of immigrant indivs. get interspersed in
genome of existing pop. thru ind. assortment and recomb.; very low amount
of gene flow is able to keep allelic diversity alive in relatively isolated pops.
, Solution 2024/2025
Pepper
positive assortative mating ANS✔✔ indivs. of like genotype mate w/ one
another; results in an increasing # of homozygous dominant and
homozygous recessive indivs., and a decreasing # of heterozygous indivs.
from one generation to the next; indivs. that carry a particular genotype are
more likely to interbreed w/ an indiv. w/ the same genotype; inbreeding
non-random mating ANS✔✔ indivs. w/ particular genotypes are
preferentially mating w/ indivs. of other particular genotypes; selection
usually done thru phenotypic expression of that particular genotypes;
reproduction w/ closer relatives often leads to a phenomenon called
inbreeding depression; assortative mating diff. than other processes bc
genotype freq. but NOT allele freq.
inbreeding depression ANS✔✔ reduction in fitness among offspring due to
increased phenotypic expression of deleterious recessive alleles; due to
non-random mating with close relatives
natural selection ANS✔✔ some alleles more frequent in next gen. bc parents
produced more offspring; ONLY process that results in Non-Random changes
(Non-Random evolutionary dir. in which a particular pop. can evolve) in
allele freqs. b/t gens.; Non-random process by which biological traits
become either more or less common in a population due to the of
differential survival and reproduction of their bearers, depending on the
presence of selection pressures in the environment
genetic drift and population sizes ANS✔✔ if a lot of offspring can be
produced, then high likelihood that anyone of alleles make it into next gen.;
if take a large sample, allele freq. can change in offspring & be higher or
lower for some, BUT also everyone of allele types make it to next gen. -
even tho large sample, still some drift, but relatively small; if take small
sample size, the prob. that each one of alleles make it to next gen. (@ same
, Solution 2024/2025
Pepper
freq.) is the SAME - prob. that error introduced in each step is much LARGER
than if take large sample size; prob. (by chance) of creating diff. allele freq.
from one gen. to next is much HIGHER if take small samples
Fixed ANS✔✔ all but one allele can be lost from pop., such that only
remaining allele in entire pop. reaches a frequency of (1.0 or 100%) -->
allele has become FIXED in that pop. - due to a very small pop. size
power of genetic drift ANS✔✔ H-W powerful in predicting probs. to inherit
particular genotype (prob. to be homo. for rec. gene) - still powerful bc start
to approach H-W @ large pop. sizes that are still FINITE (even @ large sizes,
still now fully in H-W, will always be GD from gen. to next, but very close to
it); large pop. size: violation of chance thru GD of the H-W becomes
negligible (as long as none of other evolutionary forces are present); GD
powerful, random evolutionary force in changing allele freq. if pop. shrinks
really small (usually 100 or lower, less than 100 - large fluxuations in allele
freq. due to chance alone = powerful force)
reintroducing genetic diversity ANS✔✔ genetic variation reintroduced into a
pop. once an allele has become fixed in that pop. - mutations, immigration
(move alleles b/t pop. - Gene Flow)
Gene Flow Process ANS✔✔ "leakiness" b/t diff. pops. - migration b/t diff.
areas that both have a pop. of this particular species that they keep
interbreeding - reintroduce alleles into pop.; a process that changes allele
freq. & prevents alleles from becoming FIXED; ind. assortment & crossing
over/recombination
independent assortment ANS✔✔ Gene Flow; genes on DIFFERENT
chromosomes ind. assort & mix up genetic material of a hybrid (from cross
b/t newly immigrated indiv. & indiv. present in old pop.)
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