Heredity Exam 1
Chapters 13-15
80 points
Name ______
Block ______
Multiple Choice (1 point each)
- If the liver cells of an animal have 24 chromosomes, the sperm cells would have how many chromosomes?
- 12
- 24
- 48
- twice the diploid number
- half the haploid number
- How does the sexual life cycle increase the genetic variation in a species?
- by producing gametes with different combinations of parental chromosomes
- by allowing the combination of chromosomes from two different individuals
- by allowing recombination of alleles on a chromosome
- Both A and B are correct.
- A, B, and C are correct.
- Which of the following events occurs during prophase I of meiosis?
- reduction in chromosome number
- segregation of alleles of unlinked genes
- synapsis and crossing over
- duplication of chromatids
- segregation of alleles of linked genes
- Which of the following is true of a species that has a chromosome number of 2n = 16?
- The species is diploid with 32 chromosomes.
- The species has 16 different types of chromosomes.
- There are 16 homologous pairs.
- During the S phase of the cell cycle there will be 32 separate chromosomes.
- A gamete from this species has 8 chromosomes.
- What is a karyotype?
- the phenotype of an individual
- the genotype of an individual
- a unique combination of chromosomes found in a gamete
- the kind of nucleus a cell has
- a method of organizing the homologous chromosomes of a cell in relation to their number, size, and type.
- Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?
- an unfertilized egg cell
- a sperm cell
- a male somatic cell
- a female somatic cell
- Both A and D are correct.
- Crossing over occurs during which phase of meiosis?
- prophase I
- anaphase I
- telophase I
- prophase II
- metaphase II
Use the following key to answer questions 8 – 11. Each answer may be used once, more than once, or not at all.
- The statement is true for mitosis only
- The statement is true for meiosis I only
- The statement is true for meiosis II only
- The statement is true for mitosis and meiosis I
- The statement is true for mitosis and meiosisII
- Homologous chromosomes synapse and crossing over occurs.
Answer _____
- This occurs when a cell divides to form two cells that are genetically identical.
Answer _____
- The events during this process cause the majority of genetic recombinations.
Answer _____
- The process(es) is (are) preceded by a copying (replication) of the DNA.
Answer _____
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- What is a genetic cross called between an individual of unknown genotype and homozygous recessive genotype.
- a self-cross
- a testcross
- a hybrid cross
- an F1 cross
- a dihybrid cross
- In crossing a homozygous recessive with a heterozygote, what is the chance of getting an offspring with the homozygous recessive phenotype?
- 0%
- 25%
- 50%
- 75%
- 99%
- Black fur in mice (B) is dominant to brown fur (b). Short tails (T) is dominant to long tails (t). What proportion of the progeny of the cross BbTt x BBtt will have black fur and long tails?
- 1/16
- 3/16
- 6/16
- 8/16
- 9/16
Use the information given here to answer the following questions 15-17. Feather color in budgies is determined by two different genes that affect the pigmentation of the outer feather and its core Y_B_ is green; yyB _ is blue; Y_bb is yellow; and yybb is white.
- A green budgie is crossed with a blue budgie. Which of the following results is NOT possible?
- all green offspring
- all blue offspring
- all white offspring
- all yellow offspring
- All of the above are possible, but with different probabilities.
- Two blue budgies were crossed. Over the years, they produced 22 offspring, 5 of which were white. What are the most likely genotypes for the two blue budgies?
- yyBB and yyBB
- yyBB and yyBb
- yyBb and yyBb
- yyBB and yybb
- yyBb and yybb
- The inheritance of color in budgies is an example of what genetic phenomenon?
- pleitropy
- penetrance
- polygenic inheritance
- dominance
- epistasis
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- A couple has three children, all of whom have brown eyes and blond hair. Both parents are homozygous for brown eyes (BB), but one is a blond (rr) and the other is a redhead (Rr). What is the probability that their next child will be a brown-eyed redhead?
- 1/16
- 1/8
- ¼
- ½
- 1
Use the following information to answer questions 19-21. A woman and her husband both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait.
- What is the probability that their first child will be an albino?
- 0%
- 25%
- 50%
- 75%
- 100%
- If their first two children have normal pigmentation, what is the chance that their third child will be an albino?
- 0%
- 25%
- 50%
- 75%
- 100%
- What is the chance that their fourth child will have a homozygous genotype?
- 0%
- 25%
- 50%
- 75%
- 100%
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- Given the parents AABBCc x AabbCc, assume simple dominance and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?
- ¼
- 1/8
- ¾
- 3/8
- 1
- Which of the following is an example of polygenic inheritance?
- pink flowers in snapdragons
- the ABO blood groups in humans
- sex-linkage in humans
- white and purple color in sweet peas
- skin pigmentation in humans
- A 9:3:3:1 phenotypic ratio is characteristic of the
- F1 generation of a monohybrid cross.
- F2 generation of a monohybrid cross.
- F1 generation of a dihybrid cross.
- F2 generation of a trihybrid cross.
- A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of
- complete dominance.
- multiple alleles.
- incomplete dominance.
- polygenic inheritance.
- pleiotropy.
- A 1:1:1:1 ratio of offspring from a dihybrid testcross indicates that
- the genes are linked
- the dominant organism was homozygous
- crossing over has occurred
- the genes are 25 map units apart.
- The genes are not linked.
- A color-blind son inherited his trait from his
- mother
- father
- mother, only if she is color-blind
- father, only if he is color-blind
- mother, only if she is not color-blind
- Which of the following chromosomal alterations does not alter genic balance but may alter phenotype because of difference in gene expression?
- deletion
- inversion
- duplication
- nondisjunction
- genomic imprinting
- In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW, a lethal recessive allele that causes death of the embryo occurs on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male heterozygous for the lethal allele and a normal female?
- 2:1 male to female
- 1:2 male to female
- 1:1 male to female
- 4:3 male to female
- 3:1 male to female
- The finding that defective genes behave differently in offspring depending on whether they belong to the maternal or paternal chromosomes is implicated in which of the following?
- Prader-Willi syndrome
- Fragile X syndrome
- Angelman syndrome
- Only A and C are correct
- A,B, and C are all correct
- A mammalian zygote with which of the following chromosomal abnormalities will never develop into a viable embryo?
- YO
- XO
- XXX
- XXY
- XXXY
- What does independent assortment refer to?
- The separation of alleles in anaphase I
- The random arrangement of chromosomal tetrads at metaphase I
- The separation of chromotids at anaphase 1
- The random arrangement of gene loci on a chromosome
- The fact that any pair of chromatids in a tetrad can cross over.
- The particular position of a gene on a chromosome is known as a(n)
- Allele
- Tetrad
- chiasma
- locus
- map distance
- The frequency of crossing over between any two linked genes is
- higher if they are recessive
- difficult to predict
- determined by their relative distance
- the same as if they were not linked,
- proportional to the distance between them.
- A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color-blind marries a color-blind male. What is the probability that this couple’s son will be color-blind?
- 0%
- 25%
- 50%
- 75%
- 100%
Use the following pedigree to answer questions 36-39
Europe’s Royal Families
- The above pedigree could demonstrate which of the following genetic disorders?
- Tay Sachs
- Huntington’s Disease
- Color-blindness
- Hemophilia
- Both C and D
- What is the method of inheritance of the genetic disorder?
- recessive
- dominant
- sex-linked recessive
- sex-linked dominant
- none of the above
- What is the genotype of the male that died at age 23 in column V?
- XiX
- XY
- XiY
- XX
- XYY
- What is the genotype of that individual's mother?
- XiX
- XY
- XiY
- XX
- XYY
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- The statement, “The X and Y chromosomes determine sex” is inaccurate and misleading. Which of the following statements is most accurate?
- Genes on the X and Y chromosomes determine sex.
- Genes on the X chromosome that are not present on the Y determine sex.
- Genes on the Y chromosome that are not present on the X determine sex.
- A variety of genes on other chromosomes play various roles in determining sex, and the activity of those genes is controlled by a small number of genes on the X and/or Y chromosome.
- A variety of genes on the X and/or the Y chromosomes play various roles in determining sex, and the activity of those genes is controlled by a small number of genes on other chromosomes.
______
Essay questions (20 points each.)
Answer two of the three questions.
1. C. 13- Compare and contrast the division process of a somatic cell and a gamete cell. Be sure to explain the nearly unlimited variation that gametic cell division allows.
2- C. 14- Explain Mendel’s quantitative approach, that led to his discoveries, in the principles of genetics. Describe the law of segregation, independent assortment and Mendelian rules for inheritance.
3-C. 15- Morgan was able to relate Mendelian inheritance patterns to chromosomes. How did he achieve this? Additionally, explain the following, linked genes, sex-linked inheritance and aneuploidy.