BIO 148 EXAM # STUDY GUIDE 2026
True of False.
Sexual reproduction results in offspring that are genetically identical to their parents. -
ANSWERSFalse. Sexual reproduction results in offspring that are different than their
parents and each other.
True or False.
The fusion of haploid gametes to produce a diploid offspring occurs during meiosis. -
ANSWERSFalse. The fusion of haploid gametes occurs during fertilization.
The Red Queen hypothesis states that sex is needed to.... - ANSWERSfight disease
True or False.
Genetic variation in offspring could be good or bad, depending on the circumstances. -
ANSWERSTrue. Variation can be good in the case of evolving pathogens, but could be
bad because it could create less than desirable combinations of traits in offspring.
Asexual - ANSWERSoffspring arises from a single organism and is identical to the
parent
Sexual - ANSWERSNeeds another mate in order to reproduce, only passes on half of
an individual's genes,
Looking at reproduction through a lens of fitness: Paradox of Sex - ANSWERSAsexual
reproduction would create more offspring and pass more of their genes on to the next
generation than a sexually reproducing organism. So why did sex evolve?
Paradox of Sex - ANSWERSAsexual reproduction results in more genes in the next
generation per individual.
Asexual reproduction does not require a mare and 100% of their genes are passed on
to offspring
Why did sex evolve? - ANSWERSThe most popular theory is that it has evolved due to
the huge amount of genetic diversity. In fact, one woman and one man can generate
70.6 x 10^12 genetically different offspring. That is more people than every person that
has ever lived on earth. That is a lot of diversity.
Why is genetic variation so important evolutionary? - ANSWERSConsider this scenario:
If an asexually reproducing organism dies when infected with some sort of virus for
, example, because all its offspring are genetically identical, all of the offspring would die
after exposure to the virus too.
However, if offspring are genetically varied, some will survive better than others in a
changing environment or one with pathogens (disease causing organisms). This is
called the changing environment hypothesis.
Sweaty T-shirt Study: supports the changing environment hypothesis -
ANSWERSFemales are attracted to the sweat of males that have different immune
systems than themselves. The thought behind this is that it is a fitness advantage for
offspring to have a varied immune system that can respond to more pathogens.
Sexually reproducing organisms have two copies of each gene, one inherited from each
parent. Asexually reproducing organisms usually only have one.
Why is having two copies of each gene an evolutionary advantage? - ANSWERSIt is
beneficial to have two copies of a gene because one copy can be nonfunctional and the
organism is usually unaffected because the other copy is enough for function.
Why might it be beneficial to only pass on one copy of each gene? Purifying Selection
Process. - ANSWERSIt may also be an evolutionary advantage to pass on one copy of
each gene in case one is bad.
Purifying Selection Process - ANSWERSIn asexual reproduction, all genes are passed
on to offspring, even the defective ones. Let's say a sexually reproducing organism has
one functioning copy of a gene and the other is nonfunctional. Because only one copy
of each gene is passed on during sexual reproduction, we would expect that some
offspring will lack the nonfunctional version. In this way, bad alleles (verisons of genes)
can be purified from the gene pool of a population.
Organisms produce more offspring when they reproduce asexually than sexually, yet
many organisms reproduce sexually in nature. What is a probable explanation for the
prevalence of sexual reproduction in nature? Sexual reproduction.... - ANSWERSmixes
up alleles contributing to variation in a species
The advantage of sexual reproduction over asexual reproduction is that sexual
reproduction _____________. - ANSWERSproduces offspring with greater heritable
variation on which natural selection can act
True of False.
If a sexually reproducing organism with a deleterious (bad) allele (version of a gene), all
it's offspring will inherit that allele. - ANSWERSFalse. Sexually reproducing organisms
have two copies of every gene, but they only pass on one copy. So 1/2 the offspring are
expected to lack the bad allele.
True of False.
Sexual reproduction results in offspring that are genetically identical to their parents. -
ANSWERSFalse. Sexual reproduction results in offspring that are different than their
parents and each other.
True or False.
The fusion of haploid gametes to produce a diploid offspring occurs during meiosis. -
ANSWERSFalse. The fusion of haploid gametes occurs during fertilization.
The Red Queen hypothesis states that sex is needed to.... - ANSWERSfight disease
True or False.
Genetic variation in offspring could be good or bad, depending on the circumstances. -
ANSWERSTrue. Variation can be good in the case of evolving pathogens, but could be
bad because it could create less than desirable combinations of traits in offspring.
Asexual - ANSWERSoffspring arises from a single organism and is identical to the
parent
Sexual - ANSWERSNeeds another mate in order to reproduce, only passes on half of
an individual's genes,
Looking at reproduction through a lens of fitness: Paradox of Sex - ANSWERSAsexual
reproduction would create more offspring and pass more of their genes on to the next
generation than a sexually reproducing organism. So why did sex evolve?
Paradox of Sex - ANSWERSAsexual reproduction results in more genes in the next
generation per individual.
Asexual reproduction does not require a mare and 100% of their genes are passed on
to offspring
Why did sex evolve? - ANSWERSThe most popular theory is that it has evolved due to
the huge amount of genetic diversity. In fact, one woman and one man can generate
70.6 x 10^12 genetically different offspring. That is more people than every person that
has ever lived on earth. That is a lot of diversity.
Why is genetic variation so important evolutionary? - ANSWERSConsider this scenario:
If an asexually reproducing organism dies when infected with some sort of virus for
, example, because all its offspring are genetically identical, all of the offspring would die
after exposure to the virus too.
However, if offspring are genetically varied, some will survive better than others in a
changing environment or one with pathogens (disease causing organisms). This is
called the changing environment hypothesis.
Sweaty T-shirt Study: supports the changing environment hypothesis -
ANSWERSFemales are attracted to the sweat of males that have different immune
systems than themselves. The thought behind this is that it is a fitness advantage for
offspring to have a varied immune system that can respond to more pathogens.
Sexually reproducing organisms have two copies of each gene, one inherited from each
parent. Asexually reproducing organisms usually only have one.
Why is having two copies of each gene an evolutionary advantage? - ANSWERSIt is
beneficial to have two copies of a gene because one copy can be nonfunctional and the
organism is usually unaffected because the other copy is enough for function.
Why might it be beneficial to only pass on one copy of each gene? Purifying Selection
Process. - ANSWERSIt may also be an evolutionary advantage to pass on one copy of
each gene in case one is bad.
Purifying Selection Process - ANSWERSIn asexual reproduction, all genes are passed
on to offspring, even the defective ones. Let's say a sexually reproducing organism has
one functioning copy of a gene and the other is nonfunctional. Because only one copy
of each gene is passed on during sexual reproduction, we would expect that some
offspring will lack the nonfunctional version. In this way, bad alleles (verisons of genes)
can be purified from the gene pool of a population.
Organisms produce more offspring when they reproduce asexually than sexually, yet
many organisms reproduce sexually in nature. What is a probable explanation for the
prevalence of sexual reproduction in nature? Sexual reproduction.... - ANSWERSmixes
up alleles contributing to variation in a species
The advantage of sexual reproduction over asexual reproduction is that sexual
reproduction _____________. - ANSWERSproduces offspring with greater heritable
variation on which natural selection can act
True of False.
If a sexually reproducing organism with a deleterious (bad) allele (version of a gene), all
it's offspring will inherit that allele. - ANSWERSFalse. Sexually reproducing organisms
have two copies of every gene, but they only pass on one copy. So 1/2 the offspring are
expected to lack the bad allele.
