BIOL 110 EXAM 3 PSU QUESTIONS
WITH CORRECT ANSWERS
What is complete dominance? - Correct Answers -A form of dominance wherein the
dominant allele completely masks the effect of the recessive allele in heterozygous
condition
What is incomplete dominance? - Correct Answers -when individuals who are
heterozygous exhibit a phenotype intermediate b/w homozygous individuals
What is codominance? - Correct Answers -when both alleles are expressed in the
phenotype of heterozygous individuals
What is phenotype? - Correct Answers -physical characteristics of an organism
What is polygenic inheritance? - Correct Answers -when a character is controlled by
more than one gene
What is a carrier (heterozygote)? - Correct Answers -a person that has inherited a
recessive allele for a trait that they themselves don't display
What three diseases are caused by deleterious recessive alleles? - Correct Answers -
cystic fibrosis, phenylketonuria, and sickle-cell disease
parents must BOTH be heterozygous carriers
What is pleiotrophy? - Correct Answers -when one gene has multiple effects on
phenotype (i.e. people w/ albinism tend to also have issues w/ crossed eyes)
What is epistasis? - Correct Answers -when one gene affects the expression of another
gene
i.e. horses with a homozygous cc allele will be albino no matter the alleles for color they
have
What is heterozygote advantage? - Correct Answers -the situation in which the
heterozygote has is better fit and is able to survive/reproduce well
, What causes cystic fibrosis? - Correct Answers -inbalance in salt levels that causes a
greater amount of mucus in cells of lung/intestines
Name for the sequence of DNA bases that signal the beginning of RNA synthesis? -
Correct Answers -promotors
Name of the DNA sequence that ends RNA synthesis? - Correct Answers -terminator
sequence
What type of RNA combines with proteins to form ribosomes? - Correct Answers -
ribosomal RNA (rRNA)
What disease is the best example of natural selection in humans as well as one of the
best examples of heterozygote advantage? - Correct Answers -Sickle cell anemia
What is a good example of a disease in which phenotype is strongly affected by
environment? - Correct Answers -PKU
What is wild-type phenotype? - Correct Answers -the most common phenotype for a
character
i.e. red eyes are the wild-type for fruit flies
What is a mutant phenotype? - Correct Answers -an observed phenotype that is less
common than the wild-type
i.e. a fruit fly with white eyes would display a mutant phenotype
How would a mutant phenotype vs a wild-type phenotype be characterized?
w+ / w - Correct Answers -Mutant= w
Wild= w+
X and Y chromosomes are examples of... - Correct Answers -sex chromosomes
What are sex-linked genes? - Correct Answers -genes that are found on sex
chromosomes
All chromosomes (other than sex chromosomes) are called... - Correct Answers -
autosomes
What is the SRY gene responsible for? - Correct Answers -the initiation of male sex
determination in humans
WITH CORRECT ANSWERS
What is complete dominance? - Correct Answers -A form of dominance wherein the
dominant allele completely masks the effect of the recessive allele in heterozygous
condition
What is incomplete dominance? - Correct Answers -when individuals who are
heterozygous exhibit a phenotype intermediate b/w homozygous individuals
What is codominance? - Correct Answers -when both alleles are expressed in the
phenotype of heterozygous individuals
What is phenotype? - Correct Answers -physical characteristics of an organism
What is polygenic inheritance? - Correct Answers -when a character is controlled by
more than one gene
What is a carrier (heterozygote)? - Correct Answers -a person that has inherited a
recessive allele for a trait that they themselves don't display
What three diseases are caused by deleterious recessive alleles? - Correct Answers -
cystic fibrosis, phenylketonuria, and sickle-cell disease
parents must BOTH be heterozygous carriers
What is pleiotrophy? - Correct Answers -when one gene has multiple effects on
phenotype (i.e. people w/ albinism tend to also have issues w/ crossed eyes)
What is epistasis? - Correct Answers -when one gene affects the expression of another
gene
i.e. horses with a homozygous cc allele will be albino no matter the alleles for color they
have
What is heterozygote advantage? - Correct Answers -the situation in which the
heterozygote has is better fit and is able to survive/reproduce well
, What causes cystic fibrosis? - Correct Answers -inbalance in salt levels that causes a
greater amount of mucus in cells of lung/intestines
Name for the sequence of DNA bases that signal the beginning of RNA synthesis? -
Correct Answers -promotors
Name of the DNA sequence that ends RNA synthesis? - Correct Answers -terminator
sequence
What type of RNA combines with proteins to form ribosomes? - Correct Answers -
ribosomal RNA (rRNA)
What disease is the best example of natural selection in humans as well as one of the
best examples of heterozygote advantage? - Correct Answers -Sickle cell anemia
What is a good example of a disease in which phenotype is strongly affected by
environment? - Correct Answers -PKU
What is wild-type phenotype? - Correct Answers -the most common phenotype for a
character
i.e. red eyes are the wild-type for fruit flies
What is a mutant phenotype? - Correct Answers -an observed phenotype that is less
common than the wild-type
i.e. a fruit fly with white eyes would display a mutant phenotype
How would a mutant phenotype vs a wild-type phenotype be characterized?
w+ / w - Correct Answers -Mutant= w
Wild= w+
X and Y chromosomes are examples of... - Correct Answers -sex chromosomes
What are sex-linked genes? - Correct Answers -genes that are found on sex
chromosomes
All chromosomes (other than sex chromosomes) are called... - Correct Answers -
autosomes
What is the SRY gene responsible for? - Correct Answers -the initiation of male sex
determination in humans
