Download A. FF B. Ff C. ff

RaCK LS.2.d (genotype & phenotype)
Assessment ID:
dna.1956
ib.20207
Directions: Answer the following question(s).
1
TEACHER READS:
Read the question to yourself and select the best answer.
An allele may express itself in an organism's phenotype, or it may be masked by the expression of
the other allele for that gene. What are the two categories of alleles, based on whether or not they
are expressed in the phenotype?
A. homozygous and
heterozygous
B. homozygous and
C. dominant and
recessive
heterozygous
D. dominant and
recessive
Master ID: 8987 Revision: 1
Correct: D
Rationale:
A. Student(s) may have known that any allele pair may be homozygous or heterozygous, but did not
realize that this is a category based on genotype, not on phenotype expression.
B. Student(s) knew that recessive alleles are masked by the other alleles, but did not know the second
category and guessed based on a familiar term.
C. Student(s) knew that dominant alleles are expressed, but did not know the second category and
guessed based on a familiar term.
D. Correct answer
Standards:
CS.SCI.7.LS.2.d
2
TEACHER READS:
Read the question to yourself and select the best answer.
In humans, the allele for free earlobes is dominant to the allele for attached earlobes. Which of the
following genotypes represents an individual with free earlobes?
A. FF
B. Ff
C. ff
D. Both A and B
Master ID: 27306 Revision: 1
Correct: D
Rationale:
A. Student(s) may have known that this represents the dominant allele being expressed, but may not have
realized that in a heterozygous genotype the dominant allele is expressed also.
B. Student(s) may have realized that the dominant allele is expressed in a heterozygous genotype, but
may not have realized that a homozygous dominant genotype also expresses the dominant phenotype.
C. Student(s) may have thought that the lower case letters represented the dominant allele rather than the
recessive allele.
D. Correct answer
Standards:
CS.SCI.7.LS.2.d
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Generated On March 10, 2013, 9:45 PM PDT
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Page 1
RaCK LS.2.d (genotype & phenotype)
Assessment ID:
dna.1956
ib.20207
Directions: Answer the following question(s).
3
TEACHER READS:
Read the question to yourself and select the best answer.
In humans, Cystic Fibrosis is a disorder caused by a recessive allele. Which of the following would
represent the genotype of an individual who tests positive for Cystic Fibrosis?
A. c
B. cc
C. Cc
D. CC
Master ID: 27302 Revision: 1
Correct: B
Rationale:
A. Student(s) may have known that this was the recessive allele that would carry cystic fibrosis, but may
not have realized that this just represents the allele, not the genotype.
B. Correct answer
C. Student(s) may have seen the recessive allele present and assumed that this individual must have the
disorder.
D. Student(s) may not have realized that this genotype contains 2 dominant alleles and therefore this
individual does not have cystic fibrosis.
Standards:
CS.SCI.7.LS.2.d
4
TEACHER READS:
Read the question to yourself and select the best answer.
Huntington's disease is a genetic disorder that causes the breakdown of brain tissue starting during
middle age. Huntington's is inherited by anyone carrying a dominant allele. Which of the following
genotypes is LEAST likely to have Huntington's disease?
A. HH
B. Hh
C. hH
D. hh
Master ID: 25916 Revision: 1
Correct: D
Rationale:
A. Student(s) may have mixed up the terms "dominant" and "recessive," incorrectly thinking recessive
alleles are usually written with capitalized letters. Student(s) may have believed that two dominant
alleles cancel each other out.
B. Student(s) may have incorrectly thought a person would have to inherit both dominant alleles to have
Huntington's disease.
C. Student(s) may have mistakenly assumed that the order of the alleles matters and a genotype with a
recessive allele listed first would be more likely to have the recessive phenotype.
D. Correct answer
Standards:
CS.SCI.7.LS.2.d
Illuminate Itembank™
Generated On March 10, 2013, 9:45 PM PDT
Continue: Turn to the next page.
Page 2
RaCK LS.2.d (genotype & phenotype)
Assessment ID:
dna.1956
ib.20207
Directions: Answer the following question(s).
5
TEACHER READS:
Read the question to yourself and select the best answer.
Based on the information provided in the table below which of the following alleles is recessive?
A. Yellow
B. Blue
C. Green
D. Black
Master ID: 27303 Revision: 1
Correct: B
Rationale:
A. Student(s) may have confused the terms dominant and recessive.
B. Correct answer
C. Student(s) may not have realized that the dominant gene determines the phenotype, not the recessive
gene.
D. Student(s) may not have realized what makes a gene recessive.
Standards:
CS.SCI.7.LS.2.d
Illuminate Itembank™
Generated On March 10, 2013, 9:45 PM PDT
Stop: You have finished the assessment.
Page 3