RIO BIO 156 STUDY GUIDE 2025/2026 QUESTIONS AND
ANSWERS GRADED A+
✔✔What is the normal complement of sex chromosomes in a human male? - ✔✔one X
chromosome and one Y chromosome
✔✔Which refers to the loss of a portion of a chromosome? - ✔✔deletion
✔✔Nondisjunction occurs when - ✔✔members of a chromosome pair fail to separate.
✔✔Which of the following terms refers to the situation where a single phenotypic
characteristic is determined by the additive effects of two or more genes? -
✔✔polygenic inheritance.
✔✔Which disease results in deformed red blood cells, poor circulation, and anemia? -
✔✔sickle-cell disease
✔✔Linked genes generally - ✔✔do not follow the laws of independent assortment.
✔✔When you trace the occurrence of a specific characteristic through your past
ancestry, you are constructing a family ______________. - ✔✔pedigree
✔✔Which refers to the movement of a piece of one chromosome to another
nonhomologous chromosome? - ✔✔translocation
✔✔Imagine that beak color in a finch species is controlled by a single gene. You mate a
finch homozygous for orange (pigmented) beak with a finch homozygous for ivory
(unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange
beak. This pattern of color expression is most likely to be an example of -
✔✔incomplete dominance
✔✔Recessive X-linked traits are more likely to be expressed in a male than a female
because - ✔✔the male's phenotype results entirely from his single X-linked gene.
✔✔An abnormal number of chromosomes could result during meiosis because of ____.
- ✔✔nondisjunction
✔✔What causes Down syndrome? - ✔✔an extra chromosome 21
✔✔Solve the following multiple allele problem: Susan, a mother with Type B blood, has
a child with Type O blood. She claims that Craig, who has Type A blood, is the father.
He claims that he cannot possibly be the father. Further blood tests ordered by the
, judge reveal that Craig is AA. The judge rules that - ✔✔Craig is right and doesn't have
to pay child support
✔✔Sometimes, linked genes are not inherited because they are broken apart during the
formation of the gametes. These breaks are caused by - ✔✔crossing over
✔✔The expression of both alleles for a trait in a heterozygous individual illustrates -
✔✔co-dominance
✔✔A karyotype is most like which of the following? - ✔✔Photographs of every couple at
a high school prom
✔✔By studying a karyotype, a prospective parent would be able to tell - ✔✔if there is an
alteration in the number of chromosomes.
✔✔A person who has type AB blood illustrates the principle of - ✔✔co-dominance
✔✔In a pedigree chart, which is correct? - ✔✔A line between a circle and a square
represents a mating.
✔✔How many sex chromosomes are in an egg or a sperm? - ✔✔one
✔✔A carrier of a genetic disorder who does not show symptoms is most likely to be
__________ to transmit it to offspring. - ✔✔heterozygous for the trait and able
✔✔Human skin color varies greatly from one individual to another. The specific genetic
situation to account for this fact is - ✔✔polygenic inheritance - several genes act
together to govern the phenotype of a certain characteristic.
✔✔If a colorblind woman marries a colorblind man, the chances of any daughter being
of normal vision is - ✔✔0%
✔✔A man has hemophilia, but his parents do not. Using H for normal and h for
hemophilia, give the genotype of his father, mother, and himself in that order. - ✔✔XHY,
XHXh, XhY
✔✔In the gene arrangement ABCDEFG breaks and a segment repositions itself so that
the segment now reads ABEDCFG, what specific kind of mutation has occurred? -
✔✔Inversion
✔✔Many genetic disorders of humans are caused by - ✔✔recessive alleles
✔✔Which refers to the addition of an extra segment of a chromosome? - ✔✔duplication
ANSWERS GRADED A+
✔✔What is the normal complement of sex chromosomes in a human male? - ✔✔one X
chromosome and one Y chromosome
✔✔Which refers to the loss of a portion of a chromosome? - ✔✔deletion
✔✔Nondisjunction occurs when - ✔✔members of a chromosome pair fail to separate.
✔✔Which of the following terms refers to the situation where a single phenotypic
characteristic is determined by the additive effects of two or more genes? -
✔✔polygenic inheritance.
✔✔Which disease results in deformed red blood cells, poor circulation, and anemia? -
✔✔sickle-cell disease
✔✔Linked genes generally - ✔✔do not follow the laws of independent assortment.
✔✔When you trace the occurrence of a specific characteristic through your past
ancestry, you are constructing a family ______________. - ✔✔pedigree
✔✔Which refers to the movement of a piece of one chromosome to another
nonhomologous chromosome? - ✔✔translocation
✔✔Imagine that beak color in a finch species is controlled by a single gene. You mate a
finch homozygous for orange (pigmented) beak with a finch homozygous for ivory
(unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange
beak. This pattern of color expression is most likely to be an example of -
✔✔incomplete dominance
✔✔Recessive X-linked traits are more likely to be expressed in a male than a female
because - ✔✔the male's phenotype results entirely from his single X-linked gene.
✔✔An abnormal number of chromosomes could result during meiosis because of ____.
- ✔✔nondisjunction
✔✔What causes Down syndrome? - ✔✔an extra chromosome 21
✔✔Solve the following multiple allele problem: Susan, a mother with Type B blood, has
a child with Type O blood. She claims that Craig, who has Type A blood, is the father.
He claims that he cannot possibly be the father. Further blood tests ordered by the
, judge reveal that Craig is AA. The judge rules that - ✔✔Craig is right and doesn't have
to pay child support
✔✔Sometimes, linked genes are not inherited because they are broken apart during the
formation of the gametes. These breaks are caused by - ✔✔crossing over
✔✔The expression of both alleles for a trait in a heterozygous individual illustrates -
✔✔co-dominance
✔✔A karyotype is most like which of the following? - ✔✔Photographs of every couple at
a high school prom
✔✔By studying a karyotype, a prospective parent would be able to tell - ✔✔if there is an
alteration in the number of chromosomes.
✔✔A person who has type AB blood illustrates the principle of - ✔✔co-dominance
✔✔In a pedigree chart, which is correct? - ✔✔A line between a circle and a square
represents a mating.
✔✔How many sex chromosomes are in an egg or a sperm? - ✔✔one
✔✔A carrier of a genetic disorder who does not show symptoms is most likely to be
__________ to transmit it to offspring. - ✔✔heterozygous for the trait and able
✔✔Human skin color varies greatly from one individual to another. The specific genetic
situation to account for this fact is - ✔✔polygenic inheritance - several genes act
together to govern the phenotype of a certain characteristic.
✔✔If a colorblind woman marries a colorblind man, the chances of any daughter being
of normal vision is - ✔✔0%
✔✔A man has hemophilia, but his parents do not. Using H for normal and h for
hemophilia, give the genotype of his father, mother, and himself in that order. - ✔✔XHY,
XHXh, XhY
✔✔In the gene arrangement ABCDEFG breaks and a segment repositions itself so that
the segment now reads ABEDCFG, what specific kind of mutation has occurred? -
✔✔Inversion
✔✔Many genetic disorders of humans are caused by - ✔✔recessive alleles
✔✔Which refers to the addition of an extra segment of a chromosome? - ✔✔duplication
