USABO STUDY GUIDE EXAM QUESTIONS WITH SOLUTIONS
2025 GRADED A+
✔✔Pedigree - ✔✔a diagram of a family tree with conventional symbols, showing the
occurrence of heritable characters in parents and offspring over multiple generations
✔✔Phenotypic ratio of a dihybrid cross - ✔✔9:3:3:1
✔✔Pleiotropy - ✔✔the ability of a single gene to have multiple effects
✔✔Polygenic inheritance - ✔✔an additive effect of two or more genes on a single
phenotypic character
✔✔Quantitative character - ✔✔a heritable feature that varies continuously over a range
rather than in an either-or fashion (skin color)
✔✔Testcross - ✔✔breeding an organism of unknown genotype with a homozygous
recessive individual to determine the unknown genotype
✔✔True-breeding - ✔✔referring to organisms that produce offspring of the same variety
over many generations of self-pollination
✔✔Aneuploidy - ✔✔a chromosomal aberration in which one or more chromosomes are
present in extra copies or are deficient in number
✔✔Barr body - ✔✔a dense object lying along the inside of the nuclear envelope in cells
of female mammals, representing a highly condensed, inactivated X chromosome.
✔✔Cytogenetic map - ✔✔a map of a chromosome that locates genes with respect to
chromosomal features distinguishable in a microscope
✔✔Genetic map - ✔✔an ordered list of genetic loci (genes or other genetic markers)
along a chromosome
✔✔Genetic recombination - ✔✔general term for the production of offspring with
combinations of traits that differ from those found in either parent.
✔✔Genomic imprinting - ✔✔a phenomenon in which expression of an allele in offspring
depends on whether the allele is inherited from the male or female parent.
✔✔Hemizygous - ✔✔Having only a single copy of a gene instead of the customary two
copies. All the genes on the single X chromosome in the male are _____________.
, ✔✔Linkage map - ✔✔a genetic map based on the frequencies of recombination
between barkers during crossing over of homologous chromosomes.
✔✔Linked genes - ✔✔genes located close enough together on a chromosome that they
tend to be inherited together.
✔✔Monosomic - ✔✔referring to a diploid cell that has only one copy of a particular
chromosome instead of the normal two.
✔✔Nondisjunction - ✔✔an error in meiosis or mitosis in which members of a pair of
homologous chromosomes or a pair of sister chromatids fail to separate properly from
each other.
✔✔Parental type - ✔✔an offspring with a phenotype that matches one of the true-
breeding parental phenotypes; also refers to the phenotype itself
✔✔Polyploidy - ✔✔a chromosomal alteration in which the organism possesses more
than two complete chromosome sets. it is the result of an accident of cell division.
✔✔Recombinant type - ✔✔an offspring whose phenotype differs from that of the true-
breeding P generation parents; also refers to the phenotype itself.
✔✔Sex-linked gene - ✔✔a gene located on either sex chromosome. Most _____ s are
on the X chromosome and show distinctive patterns of inheritance; there are very few
genes on the Y chromosome.
✔✔Trisomic - ✔✔referring to a diploid cell that has three copies of a particular
chromosome instead of the normal two.
✔✔Wild type - ✔✔the phenotype most commonly observed in natural populations; also
refers to the individual with that phenotype.
✔✔ Alternation of generations - ✔✔a life cycle in which there is both a multicellular
diploid form, the sporophyte, and a multicellular haploid form, the gametophyte;
characteristic of plants and some algae.
✔✔Asexual reproduction - ✔✔the generation of offspring from a single parent that
occurs without the fusion of gametes (by budding, division of a single cell, or division of
the entire organism
✔✔Autosome - ✔✔a chromosome that is not directly involved in determining sex; not a
sex chromosome
2025 GRADED A+
✔✔Pedigree - ✔✔a diagram of a family tree with conventional symbols, showing the
occurrence of heritable characters in parents and offspring over multiple generations
✔✔Phenotypic ratio of a dihybrid cross - ✔✔9:3:3:1
✔✔Pleiotropy - ✔✔the ability of a single gene to have multiple effects
✔✔Polygenic inheritance - ✔✔an additive effect of two or more genes on a single
phenotypic character
✔✔Quantitative character - ✔✔a heritable feature that varies continuously over a range
rather than in an either-or fashion (skin color)
✔✔Testcross - ✔✔breeding an organism of unknown genotype with a homozygous
recessive individual to determine the unknown genotype
✔✔True-breeding - ✔✔referring to organisms that produce offspring of the same variety
over many generations of self-pollination
✔✔Aneuploidy - ✔✔a chromosomal aberration in which one or more chromosomes are
present in extra copies or are deficient in number
✔✔Barr body - ✔✔a dense object lying along the inside of the nuclear envelope in cells
of female mammals, representing a highly condensed, inactivated X chromosome.
✔✔Cytogenetic map - ✔✔a map of a chromosome that locates genes with respect to
chromosomal features distinguishable in a microscope
✔✔Genetic map - ✔✔an ordered list of genetic loci (genes or other genetic markers)
along a chromosome
✔✔Genetic recombination - ✔✔general term for the production of offspring with
combinations of traits that differ from those found in either parent.
✔✔Genomic imprinting - ✔✔a phenomenon in which expression of an allele in offspring
depends on whether the allele is inherited from the male or female parent.
✔✔Hemizygous - ✔✔Having only a single copy of a gene instead of the customary two
copies. All the genes on the single X chromosome in the male are _____________.
, ✔✔Linkage map - ✔✔a genetic map based on the frequencies of recombination
between barkers during crossing over of homologous chromosomes.
✔✔Linked genes - ✔✔genes located close enough together on a chromosome that they
tend to be inherited together.
✔✔Monosomic - ✔✔referring to a diploid cell that has only one copy of a particular
chromosome instead of the normal two.
✔✔Nondisjunction - ✔✔an error in meiosis or mitosis in which members of a pair of
homologous chromosomes or a pair of sister chromatids fail to separate properly from
each other.
✔✔Parental type - ✔✔an offspring with a phenotype that matches one of the true-
breeding parental phenotypes; also refers to the phenotype itself
✔✔Polyploidy - ✔✔a chromosomal alteration in which the organism possesses more
than two complete chromosome sets. it is the result of an accident of cell division.
✔✔Recombinant type - ✔✔an offspring whose phenotype differs from that of the true-
breeding P generation parents; also refers to the phenotype itself.
✔✔Sex-linked gene - ✔✔a gene located on either sex chromosome. Most _____ s are
on the X chromosome and show distinctive patterns of inheritance; there are very few
genes on the Y chromosome.
✔✔Trisomic - ✔✔referring to a diploid cell that has three copies of a particular
chromosome instead of the normal two.
✔✔Wild type - ✔✔the phenotype most commonly observed in natural populations; also
refers to the individual with that phenotype.
✔✔ Alternation of generations - ✔✔a life cycle in which there is both a multicellular
diploid form, the sporophyte, and a multicellular haploid form, the gametophyte;
characteristic of plants and some algae.
✔✔Asexual reproduction - ✔✔the generation of offspring from a single parent that
occurs without the fusion of gametes (by budding, division of a single cell, or division of
the entire organism
✔✔Autosome - ✔✔a chromosome that is not directly involved in determining sex; not a
sex chromosome
