BIO 235 CERTIFICATION SCRIPT 2026
QUESTIONS WITH SOLUTIONS GRADED A+
◍ Clownfish are born male, but can change into females later in life. What
type of sexual development do clownfish demonstrate?.
Answer: sequential hermaphroditism
◍ What is an allele?.
Answer: one or multiple alternative forms of a gene
◍ What is hypostatic gene?.
Answer: Gene that is masked or suppressed by the action of a gene at a
different locus.
◍ What concept in genetics best describes the fact that a gene controlling fur
color in cats also affects vision?.
Answer: pleiotropy
◍ What is incomplete dominance?.
Answer: phenotype of the heterozygote is intermediate between the
phenotypes of the two homozygotes.
◍ A mother with blood type B has a child with blood type O. Give all possible
blood types for the father of this child.
Answer: A, B, O
◍ What is recessive epistasis?.
Answer: recessive genotype on one gene inhibits expression of other gene
◍ In rabbits, an allelic series helps to determine coat color: C (full color), cch
(chinchilla; gray color), ch (Himalayan; white withblack extremities), and c
(albino; all white). The C allele is dominant to all others, cch is dominant to
ch and c, ch is dominant to c,and c is recessive to all the other alleles. This
dominance hierarchy can be summarized as C > cch > ch > c. Indicate
, thephenotypic ratios expected of rabbits with the cross Cch × chc.
Answer: 1 full color : 1 Himalayan
◍ What are the characteristics of cytoplasmic inherited traits?.
Answer: - present in male and females.- usually inherited from one, typically
the maternal parent.- reciprocal crosses give different results. - exhibit
extensive phenotypic variation, even within a single family.
◍ what is a gene?.
Answer: an inherited factor that helps determine a trait
◍ What does a dominant allele kill?.
Answer: both heterozygotes and homozygotes.
◍ Explain the XX-XO system.
Answer: - XX: female-XO: male
◍ In a certain species of plant, flowers occur in three colors: blue, pink, and
white. A pure-breeding pink plant is mated with apure-breeding white plant.
All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants
occur in the ratio 9 blue : 3pink : 4 white. The genotype that produces white
is ww. The presence of one W allele allows pink or blue color to occur. The
alleles at the hypostatic locus are B (blue) and b (pink). What is the
genotype of the white parent?.
Answer: BB ww
◍ Fruit color is determined by two unlinked autosomal loci in plums. You
cross a homozygous plum plant that produces whitefruit with a homozygous
plum plant that produces purple fruit. All of the F1 progeny have white fruit.
When you cross the F1plants with each other, the following results are
obtained: 12 white fruit, 3 pink fruit, 1 purple fruit. What gene interaction
type explains these results?.
Answer: dominant epistasis
◍ What are quantitative characteristics?.
Answer: Continuous characteristic; displays a large number of possible
phenotypes or is encoded by multiple genetic factors.
, ◍ Which of the following is NOT normally used to study the inheritance of
human traits or disorders?.
Answer: All of these are used in the study of human traits or disorders
◍ Which of the following conditions is MOST commonly screened for in
maternal blood tests.
Answer: chromosome abnormalities and neural-tube defects
◍ You are studying a gene that controls ossicone (horn) length in giraffes. The
wild-type long-ossicone allele (L) is dominantto the mutant short-ossicone
(l) allele. However, the L allele is only 60% penetrant. You cross two
heterozygous giraffes. Whatproportion of offspring would you expect to
exhibit the long-ossicone phenotype? Assume the penetrance of L applies
equally to both homozygotes and heterozygotes.
Answer: 0.45
◍ Which type of animal uses the XX-XO system.
Answer: grasshoppers
◍ What is maternal blood screening?.
Answer: Method of screening for genetic conditions in a fetus by examining
levels of certain substances in the blood of the mother.
◍ Which organelle in an animal cell, in addition to the nucleus, contains
genes?.
Answer: mitochondrion
◍ What is the principle of segregation?.
Answer: principle of hereditary that states each individual diploid organism
possesses two alleles at a locus and that there's two alleles separate when
gametes form
◍ A mother with blood type A has a child with blood type AB. Give all
possible blood types for the father of this child.
Answer: B, AB
◍ What is a wild type?.
QUESTIONS WITH SOLUTIONS GRADED A+
◍ Clownfish are born male, but can change into females later in life. What
type of sexual development do clownfish demonstrate?.
Answer: sequential hermaphroditism
◍ What is an allele?.
Answer: one or multiple alternative forms of a gene
◍ What is hypostatic gene?.
Answer: Gene that is masked or suppressed by the action of a gene at a
different locus.
◍ What concept in genetics best describes the fact that a gene controlling fur
color in cats also affects vision?.
Answer: pleiotropy
◍ What is incomplete dominance?.
Answer: phenotype of the heterozygote is intermediate between the
phenotypes of the two homozygotes.
◍ A mother with blood type B has a child with blood type O. Give all possible
blood types for the father of this child.
Answer: A, B, O
◍ What is recessive epistasis?.
Answer: recessive genotype on one gene inhibits expression of other gene
◍ In rabbits, an allelic series helps to determine coat color: C (full color), cch
(chinchilla; gray color), ch (Himalayan; white withblack extremities), and c
(albino; all white). The C allele is dominant to all others, cch is dominant to
ch and c, ch is dominant to c,and c is recessive to all the other alleles. This
dominance hierarchy can be summarized as C > cch > ch > c. Indicate
, thephenotypic ratios expected of rabbits with the cross Cch × chc.
Answer: 1 full color : 1 Himalayan
◍ What are the characteristics of cytoplasmic inherited traits?.
Answer: - present in male and females.- usually inherited from one, typically
the maternal parent.- reciprocal crosses give different results. - exhibit
extensive phenotypic variation, even within a single family.
◍ what is a gene?.
Answer: an inherited factor that helps determine a trait
◍ What does a dominant allele kill?.
Answer: both heterozygotes and homozygotes.
◍ Explain the XX-XO system.
Answer: - XX: female-XO: male
◍ In a certain species of plant, flowers occur in three colors: blue, pink, and
white. A pure-breeding pink plant is mated with apure-breeding white plant.
All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants
occur in the ratio 9 blue : 3pink : 4 white. The genotype that produces white
is ww. The presence of one W allele allows pink or blue color to occur. The
alleles at the hypostatic locus are B (blue) and b (pink). What is the
genotype of the white parent?.
Answer: BB ww
◍ Fruit color is determined by two unlinked autosomal loci in plums. You
cross a homozygous plum plant that produces whitefruit with a homozygous
plum plant that produces purple fruit. All of the F1 progeny have white fruit.
When you cross the F1plants with each other, the following results are
obtained: 12 white fruit, 3 pink fruit, 1 purple fruit. What gene interaction
type explains these results?.
Answer: dominant epistasis
◍ What are quantitative characteristics?.
Answer: Continuous characteristic; displays a large number of possible
phenotypes or is encoded by multiple genetic factors.
, ◍ Which of the following is NOT normally used to study the inheritance of
human traits or disorders?.
Answer: All of these are used in the study of human traits or disorders
◍ Which of the following conditions is MOST commonly screened for in
maternal blood tests.
Answer: chromosome abnormalities and neural-tube defects
◍ You are studying a gene that controls ossicone (horn) length in giraffes. The
wild-type long-ossicone allele (L) is dominantto the mutant short-ossicone
(l) allele. However, the L allele is only 60% penetrant. You cross two
heterozygous giraffes. Whatproportion of offspring would you expect to
exhibit the long-ossicone phenotype? Assume the penetrance of L applies
equally to both homozygotes and heterozygotes.
Answer: 0.45
◍ Which type of animal uses the XX-XO system.
Answer: grasshoppers
◍ What is maternal blood screening?.
Answer: Method of screening for genetic conditions in a fetus by examining
levels of certain substances in the blood of the mother.
◍ Which organelle in an animal cell, in addition to the nucleus, contains
genes?.
Answer: mitochondrion
◍ What is the principle of segregation?.
Answer: principle of hereditary that states each individual diploid organism
possesses two alleles at a locus and that there's two alleles separate when
gametes form
◍ A mother with blood type A has a child with blood type AB. Give all
possible blood types for the father of this child.
Answer: B, AB
◍ What is a wild type?.
