1
LS15 MIDTERM - UCLA Phelan
1. Scientific thinking, what is it for? and be able to use it - ANS
ER
10. How is genetic drift related to Mendel's 1st law? - ANS - genetic drift is a
H
random change in allele frequencies
- mendel's law of segregation is that a gamete receives only 1 allele for each gene
IG
(are haploid)
- they are related because the gamete needs to be haploid so that when
H
fertilization occurs, the species' diploid number is maintained. And when
G
fertilization occurs, a random allele for each trait is passed on by each parents
which could lead to a random change in allele frequencies
IN
11. Sexual selection, what is it and why does it sometimes lead to tradeoffs? -
Y
ANS - individuals of one sex acquire mates from the other sex
L
- causes: male to male competition or female choice
F
- "costly" traits: traits that increase an individual's status/appeal but is harmful to
them
ex: bird's with big red bellies, long tailed birds
, 2
12. Reaction norms: how does the slope describe the relationship between
genotypes and phenotypes? - ANS - the set of all phenotypic expressions
possible for a given genotype if raised under all possible different environmental
conditions
R
- x axis: environment
E
- y axis: phenotype
H
- steep norm of reaction vs flat norm of reaction defines the influence of the
environment on the phenotype
G
- nature vs nurture
HI
13. What is evolutionary fitness? Why does evolution lead to selfish behaviors at
G
the expense of those best for the species? - ANS - evolutionary fitness is
the relative success of an organism's reproductive success; how much market
N
share their alleles have
I
- it leads to selfish behaviors because if everyone decides to produce less
Y
children to reduce the rate we use up all our resources, if one individual has an
L
allele that makes them not care and produce 10 children, then in the next
F
generation there will be 10 people who also has the allele of not caring and
producing 10 more children of their own --> market share of people who do not
care increase and market share of people who do decreases
- group selection
, 3
14. How do dominant and recessive alleles differ? - ANS - a recessive allele
only shows if the individuals has 2 copies of the recessive allele
ex: blue eyes is recessive, you need 2 copies of the allele to have blue eyes
R
- a dominant allele always shows, even if there is only 1 copy of it
E
ex: the allele for brown eyes is dominant; if you have 1 copy of the allele or 2
H
copies of it, you will have brown eyes
G
15. What was Mendel's 1st law and why do offspring look like their parents? -
I
ANS - Mendel's 1st law was segregation: a gamete receives only 1 allele for
H
each gene
G
- offspring look like their parents because they inherit one allele from each for
every trait which is reflected in their phenotypic resemblance which includes their
N
biochemical characteristics, behavior, risks for disease, appearance...
YI
16. Why don't full siblings look identical to each other? - ANS - Mendel's 1st
L
law of segregation is that a gamete receives only 1 allele for each gene
F
- mother and father each have 2 alleles for a trait but only pass on 1 to their
offspring
- sibling don't look identical to each other because they could either have
inherited the same alleles for a trait, or inherited none of the same alleles for a
trait, or inherited one common allele for a trait
LS15 MIDTERM - UCLA Phelan
1. Scientific thinking, what is it for? and be able to use it - ANS
ER
10. How is genetic drift related to Mendel's 1st law? - ANS - genetic drift is a
H
random change in allele frequencies
- mendel's law of segregation is that a gamete receives only 1 allele for each gene
IG
(are haploid)
- they are related because the gamete needs to be haploid so that when
H
fertilization occurs, the species' diploid number is maintained. And when
G
fertilization occurs, a random allele for each trait is passed on by each parents
which could lead to a random change in allele frequencies
IN
11. Sexual selection, what is it and why does it sometimes lead to tradeoffs? -
Y
ANS - individuals of one sex acquire mates from the other sex
L
- causes: male to male competition or female choice
F
- "costly" traits: traits that increase an individual's status/appeal but is harmful to
them
ex: bird's with big red bellies, long tailed birds
, 2
12. Reaction norms: how does the slope describe the relationship between
genotypes and phenotypes? - ANS - the set of all phenotypic expressions
possible for a given genotype if raised under all possible different environmental
conditions
R
- x axis: environment
E
- y axis: phenotype
H
- steep norm of reaction vs flat norm of reaction defines the influence of the
environment on the phenotype
G
- nature vs nurture
HI
13. What is evolutionary fitness? Why does evolution lead to selfish behaviors at
G
the expense of those best for the species? - ANS - evolutionary fitness is
the relative success of an organism's reproductive success; how much market
N
share their alleles have
I
- it leads to selfish behaviors because if everyone decides to produce less
Y
children to reduce the rate we use up all our resources, if one individual has an
L
allele that makes them not care and produce 10 children, then in the next
F
generation there will be 10 people who also has the allele of not caring and
producing 10 more children of their own --> market share of people who do not
care increase and market share of people who do decreases
- group selection
, 3
14. How do dominant and recessive alleles differ? - ANS - a recessive allele
only shows if the individuals has 2 copies of the recessive allele
ex: blue eyes is recessive, you need 2 copies of the allele to have blue eyes
R
- a dominant allele always shows, even if there is only 1 copy of it
E
ex: the allele for brown eyes is dominant; if you have 1 copy of the allele or 2
H
copies of it, you will have brown eyes
G
15. What was Mendel's 1st law and why do offspring look like their parents? -
I
ANS - Mendel's 1st law was segregation: a gamete receives only 1 allele for
H
each gene
G
- offspring look like their parents because they inherit one allele from each for
every trait which is reflected in their phenotypic resemblance which includes their
N
biochemical characteristics, behavior, risks for disease, appearance...
YI
16. Why don't full siblings look identical to each other? - ANS - Mendel's 1st
L
law of segregation is that a gamete receives only 1 allele for each gene
F
- mother and father each have 2 alleles for a trait but only pass on 1 to their
offspring
- sibling don't look identical to each other because they could either have
inherited the same alleles for a trait, or inherited none of the same alleles for a
trait, or inherited one common allele for a trait
