BIO 148 Exam 3 Questions and
Answers|2025 Update
Allele - Answer- A particular version of a gene.
Same locus on same chromosome type.
Same length, same switches, same activators.
Similar nucleotide sequence but NOT identical.
Crossing Over - Answer- The exchange of segments of non sister chromatids between
a pair of homologous chromosomes that occurs during meiosis 1.
Cytokinesis - Answer- Division of the cytoplasm to form two daughter cells. Typically
occurs immediately after division of the nucleus by mitosis or meiosis.
Dihybrid Cross - Answer- A mating between two parents that are heterozygous for both
of the two genes being studied.
Dominant - Answer- Referring to an allele that determines the phenotype of a
heterozygous individual.
Fertilization - Answer- The fusion of an egg and a sperm to form a diploid zygote. DNA
molecules NOT fuse during fertilization.
Gamete - Answer- A haploid reproductive cell that can fuse with another haploid cell to
form a zygote. Most
multicellular eukaryotes have two distinct forms of gametes: egg cells (ova) and sperm
cells.
Gene - Answer- A section of DNA that encodes a protein (or a functional RNA) and its
associated regulatory sequences.
Genotype - Answer- All of the alleles of every gene present in a given individual. May
refer specifically to the alleles of a particular set of genes under study.
Haploid number - Answer- The number of distinct chromosome sets in a cell.
Symbolized as n.
Heterozygous - Answer- Having two different alleles of a certain gene.
Homologous Chromosomes - Answer- In a diploid organism, chromosomes that are
similar in size, shape, and gene content. Homologs carry the same genes in the same
location, but may carry different versions (alleles) of those genes.
Homozygous - Answer- Having two identical alleles of a certain gene.
, Independent Assortment - Answer- The concept that each pair of hereditary elements
(alleles of the same gene) behaves independently of other genes during meiosis.
Law of Segregation - Answer- The concept that each pair of hereditary elements (alleles
of the same gene) separate from each other during the formation of offspring (i.e.,
during meiosis).
Locus - Answer- A gene's physical location on a chromosome.
Meiosis 1 - Answer- The first cell division of meiosis, in which synapsis and crossing
over occur, and homologous chromosomes are separated from each other, producing
daughter cells with half as many chromosomes (each composed of two sister
chromatids) as the parent cell.
Meiosis 2 - Answer- The second cell division of meiosis, in which sister chromatids are
separated from each other. Meiosis 2 does not reduce chromosome number.
Meiosis - Answer- In sexually reproducing organisms, a special two-stage type of cell
division in which one diploid (2n) parent cell produces 4 haploid (n) reproductive cells
(gametes); results in halving of the chromosome number.
Model Organism - Answer- An organism selected for intensive scientific study based on
features that make it easy to work with (e.g., body size, life span), in the hope that
findings will apply to other species.
Monohybrid Cross - Answer- A mating between two parents that are both heterozygous
for a given gene.
Nonhomologous chromosomes - Answer- Chromosomes that are different sizes and
shapes and have different DNA sequences. Non homologous chromosomes contain
different genes. Chromosome 1 and Chromosome 2 in humans are non homologous.
Nonsister chromatids - Answer- The chromatids of a particular type of chromosome
(after replication) with respect to the chromatids of its homologous chromosome.
Crossing over occurs between non sister chromatids.
Phenotype - Answer- The detectable physical and physiological traits of an individual,
which are determined its genetic makeup. Also specific trait associated with a particular
allele.
Punnett Square - Answer- A diagram that depicts the genotypes that should appear in
offspring of a certain cross.
Recessive - Answer- Referring to an allele whose phenotypic effect is observed only in
homozygous individuals (masked in heterozygous individuals).
Answers|2025 Update
Allele - Answer- A particular version of a gene.
Same locus on same chromosome type.
Same length, same switches, same activators.
Similar nucleotide sequence but NOT identical.
Crossing Over - Answer- The exchange of segments of non sister chromatids between
a pair of homologous chromosomes that occurs during meiosis 1.
Cytokinesis - Answer- Division of the cytoplasm to form two daughter cells. Typically
occurs immediately after division of the nucleus by mitosis or meiosis.
Dihybrid Cross - Answer- A mating between two parents that are heterozygous for both
of the two genes being studied.
Dominant - Answer- Referring to an allele that determines the phenotype of a
heterozygous individual.
Fertilization - Answer- The fusion of an egg and a sperm to form a diploid zygote. DNA
molecules NOT fuse during fertilization.
Gamete - Answer- A haploid reproductive cell that can fuse with another haploid cell to
form a zygote. Most
multicellular eukaryotes have two distinct forms of gametes: egg cells (ova) and sperm
cells.
Gene - Answer- A section of DNA that encodes a protein (or a functional RNA) and its
associated regulatory sequences.
Genotype - Answer- All of the alleles of every gene present in a given individual. May
refer specifically to the alleles of a particular set of genes under study.
Haploid number - Answer- The number of distinct chromosome sets in a cell.
Symbolized as n.
Heterozygous - Answer- Having two different alleles of a certain gene.
Homologous Chromosomes - Answer- In a diploid organism, chromosomes that are
similar in size, shape, and gene content. Homologs carry the same genes in the same
location, but may carry different versions (alleles) of those genes.
Homozygous - Answer- Having two identical alleles of a certain gene.
, Independent Assortment - Answer- The concept that each pair of hereditary elements
(alleles of the same gene) behaves independently of other genes during meiosis.
Law of Segregation - Answer- The concept that each pair of hereditary elements (alleles
of the same gene) separate from each other during the formation of offspring (i.e.,
during meiosis).
Locus - Answer- A gene's physical location on a chromosome.
Meiosis 1 - Answer- The first cell division of meiosis, in which synapsis and crossing
over occur, and homologous chromosomes are separated from each other, producing
daughter cells with half as many chromosomes (each composed of two sister
chromatids) as the parent cell.
Meiosis 2 - Answer- The second cell division of meiosis, in which sister chromatids are
separated from each other. Meiosis 2 does not reduce chromosome number.
Meiosis - Answer- In sexually reproducing organisms, a special two-stage type of cell
division in which one diploid (2n) parent cell produces 4 haploid (n) reproductive cells
(gametes); results in halving of the chromosome number.
Model Organism - Answer- An organism selected for intensive scientific study based on
features that make it easy to work with (e.g., body size, life span), in the hope that
findings will apply to other species.
Monohybrid Cross - Answer- A mating between two parents that are both heterozygous
for a given gene.
Nonhomologous chromosomes - Answer- Chromosomes that are different sizes and
shapes and have different DNA sequences. Non homologous chromosomes contain
different genes. Chromosome 1 and Chromosome 2 in humans are non homologous.
Nonsister chromatids - Answer- The chromatids of a particular type of chromosome
(after replication) with respect to the chromatids of its homologous chromosome.
Crossing over occurs between non sister chromatids.
Phenotype - Answer- The detectable physical and physiological traits of an individual,
which are determined its genetic makeup. Also specific trait associated with a particular
allele.
Punnett Square - Answer- A diagram that depicts the genotypes that should appear in
offspring of a certain cross.
Recessive - Answer- Referring to an allele whose phenotypic effect is observed only in
homozygous individuals (masked in heterozygous individuals).
