BIS2B Midterm 2

Question 1

Blended inheritance

Answer 1

hereditary determinants in the egg and sperm are irreversibly blended (e.g. red + white flowers= pink flowers)

Question 2

Particulate inheritance

Answer 2

hereditary determinants in the egg and sperm are passed to its offspring through genes, which keep their ability to be expressed while not always being physically seen in a descending generation

Question 3

Segregation (Mendel’s 1st law)

Answer 3

When an individual produces gametes, the two copies of its gene segregate, so that each gamete receives only one copy (one maternal haploid + one paternal haploid= one offspring diploid)

Question 4

Alleles

Answer 4

different variations of a gene (e.g. R, r)

Question 5

Genotype

Answer 5

diploid individual’s combination of alleles (RR, rr, Rr)

Question 6

Homozygous

Answer 6

similar combination of alleles (RR, rr)

Question 7

Heterozygous

Answer 7

different combination of alleles (Rr)

Question 8

Phenotype

Answer 8

trait expressed by organism (PHenotype= PHysical appearance)

Question 9

Dominant

Answer 9

phenotype expressed in heterozygotes

Question 10

Recessive

Answer 10

phenotype expressed in homozygotes only

Question 11

Incompletely dominant

Answer 11

intermediate heterozygote phenotype (white+red=pink)

Question 12

Codominant

Answer 12

both allele phenotypes are expressed in heterozygotes

Question 13

Dihybrid cross

Answer 13

test cross done when different loci assort independently

Question 14

Test cross

Answer 14

done in order to determinate genotype(whether heterozygous or homozygous) when a dominant phenotype appears

Question 15

Independent assortment

Answer 15

alleles of different genes assort independently during gamete formation

Question 16

Additive effect

Answer 16

phenotypic effects at one locus are independent of genotype at the other locus

Question 17

Locus

Answer 17

the physical location of a gene in the chromosome

Question 18

Polygenic traits

Answer 18

traits that are controlled by many genes of small effect

Question 19

Pleiotropy

Answer 19

allelic variation at one locus affects multiple traits

Question 20

Antagonistic pleiotropy

Answer 20

occurs when a single allele has both positive and negative effects

Question 21

Epistasis

Answer 21

phenotypic effect of allele at one locus depends upon genotype of allele at another locus

Question 22

Genotype x environmental interaction

Answer 22

phenotypic effect of allele or genotype depends on environment (temperature dependent allele, mutations depending on dietary factors)

Question 23

Genotype frequency

Answer 23

proportion of individuals with a genotype in a population

Question 24

Allele frequency

Answer 24

proportion of an allele across all individuals in the population or in the gametes produced by those individuals

Question 25

Gene pool

Answer 25

all of the alleles present in members of the population

Question 26

Hardy Weinberg Equilibrium assumptions

Answer 26

1. No new mutations 2. Large population 3. No genetic flow (no migration) 4. No natural selection 5. Random mating

Question 27

Genetic drift

Answer 27

random changes in allelic frequencies due to sampling error from generation to generation (sampling error much more significant in smaller populations)

Question 28

Bottleneck

Answer 28

occurs when population size is reduced for at least one generation (e.g. hunting)

Question 29

Founder effects

Answer 29

occurs when a new colony is started by a few members from the original population (e.g. Dutch settlers in South Africa- Huntington's disease)

Question 30

Non-random mating

Answer 30

occurs when individuals choose mates w particular phenotypes or genotypes

Question 31

Assortative mating

Answer 31

mating b/n similar genotypes

Question 32

Disassortative mating

Answer 32

mating b/n dissimilar individuals

Question 33

Outbreeding

Answer 33

avoidance of mating b/n relatives

Question 34

Interbreeding

Answer 34

mating b/n relatives

Question 35

Gene flow

Answer 35

migration of individuals and/or gametes from one population to another resulting in transfer of their alleles b/n populations

Question 36

Disease resistance (heterozygote advantage)

Answer 36

disease resistance alleles may confer resistance vs. different pathogens

Question 37

Antagonistic pleiotropy (heterozygote advantage)

Answer 37

heterozygote balances costs and benefits of each allele

Question 38

Metabolic pathways (heterozygote advantafe)

Answer 38

heterozygotes may have broader environmental tolerance than "specialist" homozygotes

Question 39

Interspecific competition

Answer 39

competition between members of two or more different species

Question 40

Intraspecific competition

Answer 40

competition between members of the same species

Question 41

Competition

Answer 41

both species harmed by the interaction (in interspecific interactions)

Question 42

Ammensalism

Answer 42

one species harmed, one species unaffected

Question 43

Antagonistic interactions

Answer 43

one species benefits and the other is harmed

Question 44

Competition

Answer 44

occurs when individuals harm one another; leads to decreased growth, survival, or reproduction; results in lower population growth rates

Question 45

R* rule

Answer 45

for two species competing for a single-limiting resource, the species that can suppress the resource to the lower equilibrium value (R*) will competitively exclude the other species

Question 46

Exploitative mechanism

Answer 46

when one individual uses a resource, one cannot; not encounter each other

Question 47

Interference mechanism

Answer 47

competitors confront each other and harass, chase, or prohibit others from using resources

Question 48

Niche utilization curve

Answer 48

frequency at which a species uses a range of resource types; performance of a species for a range of environmental conditions (e.g. reproduction)

Question 49

Niche overlap

Answer 49

corresponds to the region of overlap b/n resource use curves for two competing species (shaded region b/n curves)

Question 50

Character displacement

Answer 50

difference b/n similar species are greater in places where they co-occur and minimal in places where their distributions do not overlap