BIL 160 Exam 2 (Krempels) Questions and Answers Latest Update 2025
Conditions of Hardy Weinberg Equilibrium (no evolution) - Answers 1. No mutation
2. Infinite population
3. Non-assortative mating
4. No migration
5. No natural selection
Genetic Drift - Answers The smaller the population, the less genetically diverse it is (alleles can
be lost from one generation to another).
Founder Effect - Answers A small sample of breeding individuals from a large population
colonizes a new area and stops breeding with the source population.
Bottleneck Effect - Answers A large population is almost wiped out by a random event (i.e. a
natural disaster ) that randomly kills individuals. Only the lucky few survive to be the progenitors
of the population.
Random Mating - Answers Mating not influenced by genotypic or phenotypic characteristics.
Ecological Isolation - Answers The geographic ranges two species overlap, but their ecological
needs or breeding requirements differ enough to causes reproductive isolation.
Temporal Isolation - Answers Two species whose ranges overlap have different periods of
sexual activity or breeding seasons.
Behavioral Isolation - Answers Species with complex courtship rituals (i.e. breeding calls,
dances, etc...) usually exhibit a "give and take" between males and females before the mating
takes place.
Mechanical Isolation - Answers Morphological differences prevent mating/pollination.
Gametic Isolation - Answers Sperm and ova of the two species are chemically (genetically)
different and incompatible. They will not fuse and form a zygote.
Hybrid Inviability - Answers A zygote may form with the union of a sperm and egg from two
species but the embryo will die after a few cell divisions. There is not enough genetic
information from the parents to carry the organisms through morphogenesis.
Hybrid Sterility - Answers Viable hybrid is produced but is unable to reproduce due to meiotic
issues.
Hybrid Breakdown - Answers Successive generations of hybrids suffer greatly lowered fertility
and therefore sterility. They are eventually selected out of the population.
, Species Reinforcement - Answers Hybrids have lower fitness than either parent species;
reproductive isolation is maintained due to lack of hybrid survival/reproduction.
Species Fusion - Answers Two species in a hybrid zone may have weak reproductive isolating
barriers, and the two species, may over time, share a common gene pool.
Species Stability/Hybrid Equilibrium - Answers Hybrids are continually produced by the two
parent populations in a hybrid zone. A narrow hybrid zone can foster constant hybridization with
reduced hybrid survival.
Hybrid Speciation - Answers Hybrids may actually be reproductively superior to the parent
counterparts, and if the hybrids tend to interbreed this can bring about their own speciation.
Microevolution - Answers Evolutionary change within a species or a small group of organisms,
especially over a short period.
Macroevolution - Answers Major evolutionary change; specifically the evolution of whole
taxonomic groups over long periods of time.
Mitosis - Answers The diploid division of somatic cells in which the daughter cells have the
same number of genes as the parents cells
Meiosis - Answers The haploid division of sex cells (gametes) such as spermatogenesis and
oogenesis. The daughter cells have half the genetic material of the parent cells (n, 23
chromosomes instead of 46 in humans).
Mutation - Answers The changing of the structure of a gene, resulting in a variant form that may
be transmitted to subsequent generations.
Propagule - Answers Any material that functions in propagating a parent organism to the next
generation (seed, spore, zygote, asexual bud, etc...).
Genetic Recombination - Answers The recombination of genes during meiosis (i.e. crossing
over of chromosomes).
Clone - Answers A group of genetically identical organisms (i.e. those produced asexually).
Polymorphism - Answers The existence, in a population, of more than one form of a particular
trait.
Ploidy - Answers The number of complete chromosome sets
Aneuploidy - Answers "Not true" ploidy, more or fewer members than two of each homologous
pair of chromosomes are present
Monosomy - Answers Only one member of a homologous pair is present
Conditions of Hardy Weinberg Equilibrium (no evolution) - Answers 1. No mutation
2. Infinite population
3. Non-assortative mating
4. No migration
5. No natural selection
Genetic Drift - Answers The smaller the population, the less genetically diverse it is (alleles can
be lost from one generation to another).
Founder Effect - Answers A small sample of breeding individuals from a large population
colonizes a new area and stops breeding with the source population.
Bottleneck Effect - Answers A large population is almost wiped out by a random event (i.e. a
natural disaster ) that randomly kills individuals. Only the lucky few survive to be the progenitors
of the population.
Random Mating - Answers Mating not influenced by genotypic or phenotypic characteristics.
Ecological Isolation - Answers The geographic ranges two species overlap, but their ecological
needs or breeding requirements differ enough to causes reproductive isolation.
Temporal Isolation - Answers Two species whose ranges overlap have different periods of
sexual activity or breeding seasons.
Behavioral Isolation - Answers Species with complex courtship rituals (i.e. breeding calls,
dances, etc...) usually exhibit a "give and take" between males and females before the mating
takes place.
Mechanical Isolation - Answers Morphological differences prevent mating/pollination.
Gametic Isolation - Answers Sperm and ova of the two species are chemically (genetically)
different and incompatible. They will not fuse and form a zygote.
Hybrid Inviability - Answers A zygote may form with the union of a sperm and egg from two
species but the embryo will die after a few cell divisions. There is not enough genetic
information from the parents to carry the organisms through morphogenesis.
Hybrid Sterility - Answers Viable hybrid is produced but is unable to reproduce due to meiotic
issues.
Hybrid Breakdown - Answers Successive generations of hybrids suffer greatly lowered fertility
and therefore sterility. They are eventually selected out of the population.
, Species Reinforcement - Answers Hybrids have lower fitness than either parent species;
reproductive isolation is maintained due to lack of hybrid survival/reproduction.
Species Fusion - Answers Two species in a hybrid zone may have weak reproductive isolating
barriers, and the two species, may over time, share a common gene pool.
Species Stability/Hybrid Equilibrium - Answers Hybrids are continually produced by the two
parent populations in a hybrid zone. A narrow hybrid zone can foster constant hybridization with
reduced hybrid survival.
Hybrid Speciation - Answers Hybrids may actually be reproductively superior to the parent
counterparts, and if the hybrids tend to interbreed this can bring about their own speciation.
Microevolution - Answers Evolutionary change within a species or a small group of organisms,
especially over a short period.
Macroevolution - Answers Major evolutionary change; specifically the evolution of whole
taxonomic groups over long periods of time.
Mitosis - Answers The diploid division of somatic cells in which the daughter cells have the
same number of genes as the parents cells
Meiosis - Answers The haploid division of sex cells (gametes) such as spermatogenesis and
oogenesis. The daughter cells have half the genetic material of the parent cells (n, 23
chromosomes instead of 46 in humans).
Mutation - Answers The changing of the structure of a gene, resulting in a variant form that may
be transmitted to subsequent generations.
Propagule - Answers Any material that functions in propagating a parent organism to the next
generation (seed, spore, zygote, asexual bud, etc...).
Genetic Recombination - Answers The recombination of genes during meiosis (i.e. crossing
over of chromosomes).
Clone - Answers A group of genetically identical organisms (i.e. those produced asexually).
Polymorphism - Answers The existence, in a population, of more than one form of a particular
trait.
Ploidy - Answers The number of complete chromosome sets
Aneuploidy - Answers "Not true" ploidy, more or fewer members than two of each homologous
pair of chromosomes are present
Monosomy - Answers Only one member of a homologous pair is present
