Genetics Quiz: Understanding Genotypes, Phenotypes, and Inheritance Patterns, Exams of Genetics

Download Genetics Quiz: Understanding Genotypes, Phenotypes, and Inheritance Patterns and more Exams Genetics in PDF only on Docsity! BIOD 210 GENETICS Mendelian Genetics Latest Review Exam Q & A 2024 1. What is the basic unit of heredity that carries genetic information? A. Proteins B. Cells C. Genes D. Enzymes Answer: C. Genes Rationale: Genes are the basic units of heredity that carry genetic information. 2. Which of the following genotypes represents a homozygous dominant individual? A. AA B. Aa C. aa D. None of the above Answer: A. AA Rationale: Homozygous dominant individuals have two identical dominant alleles (AA). 3. If a plant with purple flowers (PP) is crossed with a plant with white flowers (pp), what will be the phenotype of the offspring? A. All purple flowers B. All white flowers C. All pink flowers D. Half purple and half white flowers Answer: A. All purple flowers Rationale: In Mendelian genetics, when crossing a homozygous dominant individual with a homozygous recessive individual, the dominant trait is expressed in the offspring. 4. What is the term used to describe the physical appearance of an organism based on its genotype? A. Phenotype B. Genotype D. 75% Answer: B. 25% Rationale: When both parents are carriers of a recessive genetic disorder, there is a 25% chance that their child will inherit two copies of the disease-causing allele and express the disorder. 11. Which of the following genetic disorders is characterized by an individual having an extra chromosome 21? A. Down syndrome B. Huntington's disease C. Cystic fibrosis D. Phenylketonuria Answer: A. Down syndrome Rationale: Down syndrome is caused by an individual having an extra copy of chromosome 21 (trisomy 21). 12. What is the term used to describe the phenomenon where multiple genes contribute to a single trait? A. Incomplete dominance B. Polygenic inheritance C. Codominance D. Mendelian genetics Answer: B. Polygenic inheritance Rationale: Polygenic inheritance is when multiple genes contribute to a single trait, leading to continuous variation. 13. If a child with blood type O is born to parents with blood types A and B, what are the possible genotypes of the parents? A. AA x BB B. AA x OO C. AO x BO D. AB x AB Answer: C. AO x BO Rationale: In this case, both parents must be carriers of the O blood type allele (genotype AO or BO) to produce a child with blood type O. 14. In Mendel's pea plant experiments, he crossed a plant with yellow seeds (YY) with a plant with green seeds (yy). What is the genotype of the F1 generation? A. YY B. Yy C. yy D. YYY Answer: B. Yy Rationale: The F1 generation of the cross between a yellow-seeded plant (YY) and a green-seeded plant (yy) will all be heterozygous (Yy). 15. In humans, the allele for brown eyes (B) is dominant over the allele for blue eyes (b). If two individuals with the genotype Bb have a child, what is the probability that the child will have blue eyes? A. 0% B. 25% C. 50% D. 75% Answer: B. 25% Rationale: When two individuals with the genotype Bb (heterozygous) have a child, there is a 25% chance that the child will inherit two copies of the recessive allele (bb) and have blue eyes. 16. Which of the following represents an example of incomplete dominance? A. Red flowers (RR) x White flowers (WW) producing pink flowers (RW) B. Black cats (BB) x White cats (WW) producing black and white spotted cats (BW) C. Straight hair (HH) x Curly hair (CC) producing wavy hair (HC) D. Blood type A (AA) x Blood type B (BB) producing blood type AB Answer: A. Red flowers (RR) x White flowers (WW) producing pink flowers (RW) Rationale: In incomplete dominance, the heterozygous genotype results in an intermediate phenotype, as seen in the cross between red and white flowers producing pink flowers. 17. Which of the following genetic disorders is caused by the absence of an enzyme needed to break down phenylalanine? A. Down syndrome B. Cystic fibrosis C. Sickle cell disease D. Phenylketonuria Answer: D. Phenylketonuria Rationale: Phenylketonuria (PKU) is caused by the absence of the enzyme phenylalanine hydroxylase, which is needed to break down phenylalanine. 18. If two individuals with the genotype AaBbCcDdEeFf have children, what is the probability of having a child with the genotype AABBCCDDEEFF? A. 1/64 B. 1/32 C. 1/16 D. 1/8 Answer: A. 1/64 Rationale: The probability of producing offspring with a specific genotype in a multihybrid cross is calculated by multiplying the individual probabilities of each allele combination, which in this case is 1/4 x 1/4 x 1/4 x 1/4 x 1/4 x 1/4 = 1/64. 19. Which of the following genetic disorders is caused by a mutation in the CFTR gene on chromosome 7? A. Down syndrome B. Cystic fibrosis C. Turner syndrome D. Klinefelter syndrome Answer: B. Cystic fibrosis Rationale: Cystic fibrosis is caused by mutations in the CFTR gene located on chromosome 7. A. Phenotype B. Genotype C. Allele D. Homozygous Answer: B. Genotype Rationale: The genotype of an organism represents its genetic composition, consisting of the alleles inherited from both parents. Question: In a monohybrid cross between two heterozygous individuals (Rr x Rr), what is the expected phenotypic ratio of the offspring? A. 1:2:1 B. 3:1 C. 9:3:3:1 D. 1:1 Answer: B. 3:1 Rationale: The expected phenotypic ratio of a monohybrid cross between two heterozygous individuals is 3:1, with three individuals showing the dominant phenotype and one individual showing the recessive phenotype. Question: Which Mendelian law states that alleles segregate independently during gamete formation? A. Law of Dominance B. Law of Segregation C. Law of Independent Assortment D. Law of Codominance Answer: C. Law of Independent Assortment Rationale: The Law of Independent Assortment states that alleles of different genes segregate independently of one another during gamete formation. Question: A man with blood type AB marries a woman with blood type O. What are the possible blood types of their offspring? A. A and B only B. A, B, and AB C. A, B, AB, and O D. O only Answer: A. A and B only Rationale: The man with blood type AB can pass on either the A or B allele to his offspring, resulting in blood types A and B in the offspring. Question: Which term describes an individual with two different alleles for a particular gene? A. Homozygous B. Heterozygous C. Dominant D. Recessive Answer: B. Heterozygous Rationale: Heterozygous individuals possess two different alleles for a specific gene, one inherited from each parent. Question: In a dihybrid cross (RrYy x RrYy), what is the expected phenotypic ratio of the offspring? A. 1:1 B. 9:3:3:1 C. 3:1 D. 9:7 Answer: B. 9:3:3:1 Rationale: The expected phenotypic ratio of a dihybrid cross is 9:3:3:1, representing the four possible combinations of alleles in the offspring. Question: What term describes the interaction between alleles where both alleles are fully expressed in the heterozygous individual? A. Incomplete Dominance B. Codominance C. Polygenic Inheritance D. Epistasis Answer: B. Codominance Rationale: Codominance occurs when both alleles at a gene locus are fully expressed in the heterozygous individual. Question: If a pea plant that is homozygous dominant for yellow seeds (YY) is crossed with a pea plant that is homozygous recessive for green seeds (yy), what will be the genotypic ratio of the offspring? A. 1:2:1 B. 1:1 C. 3:1 D. 1:0 Answer: A. 1:0 Rationale: The genotypic ratio of the offspring will be 1:0, with all offspring being heterozygous for yellow seeds (Yy). Question: Which of the following genetic disorders is caused by a deletion of a segment of chromosome 15? A. Down Syndrome B. Turner Syndrome C. Cri du Chat Syndrome D. Klinefelter Syndrome Answer: C. Cri du Chat Syndrome Rationale: Cri du Chat Syndrome is caused by the deletion of a segment of chromosome 15, leading to characteristic features including a high- pitched cry resembling a cat's cry. Question: In a pedigree analysis, what symbol is used to represent a male individual who is affected by a genetic disorder? A. Square B. Circle C. Shaded Square D. Shaded Circle Answer: C. Shaded Square Rationale: In pedigree analysis, a shaded square is used to represent a male individual who is affected by a genetic disorder. Question: Which genetic disorder is characterized by the inability to break down phenylalanine due to a deficiency in the enzyme phenylalanine hydroxylase? A. Cystic Fibrosis B. Phenylketonuria C. Tay-Sachs Disease D. Hemophilia Answer: B. Phenylketonuria Rationale: Phenylketonuria (PKU) is a genetic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase, leading to the accumulation of phenylalanine in the body. progressive neurodegeneration. Question: What term describes the phenomenon where a single gene influences multiple phenotypic traits? A. Pleiotropy B. Polygenic Inheritance C. Epistasis D. Incomplete Dominance Answer: A. Pleiotropy Rationale: Pleiotropy refers to the phenomenon where a single gene has multiple effects on the phenotype of an organism. Question: In a dihybrid cross, if two individuals are crossed and all the offspring show a 9:3:3:1 phenotypic ratio, what can be inferred about the parents? A. Both parents are homozygous for all traits B. Both parents are heterozygous for all traits C. One parent is homozygous and the other is heterozyegous for all traits D. One parent is homozygous for one trait and heterozygous for the other trait Answer: B. Both parents are heterozygous for all traits Rationale: For all offspring to exhibit a 9:3:3:1 phenotypic ratio in a dihybrid cross, both parents must be heterozygous for all traits being studied. Question: Which of the following genetic disorders is characterized by the absence of one X chromosome in females? A. Down Syndrome B. Turner Syndrome C. Klinefelter Syndrome D. Cri du Chat Syndrome Answer: B. Turner Syndrome Rationale: Turner Syndrome is characterized by the absence of one X chromosome in females, leading to short stature and other physical features. Question: What term describes the phenomenon where the expression of one gene is influenced by the presence of another gene at a different locus? A. Pleiotropy B. Polygenic Inheritance C. Epistasis D. Incomplete Dominance Answer: C. Epistasis Rationale: Epistasis refers to the phenomenon where the expression of one gene is influenced by the presence of another gene at a different locus. Question: A child with blood type O is born to parents with blood types A and B. What are the possible blood types of the parents? A. A and B B. O and O C. A and O D. B and O Answer: C. A and O Rationale: The parents must be heterozygous for blood types A and B to have a child with blood type O. Question: Which of the following genetic disorders is caused by a mutation in the CFTR gene, leading to the production of thick mucus in the lungs and digestive system? A. Cystic Fibrosis B. Marfan Syndrome C. Hemophilia D. Duchenne Muscular Dystrophy Answer: A. Cystic Fibrosis Rationale: Cystic Fibrosis is caused by a mutation in the CFTR gene, resulting in the production of thick mucus that affects the lungs and digestive system. Question: In a pedigree analysis, what symbol is used to represent a female individual who is a carrier for a genetic disorder? A. Square B. Circle C. Shaded Square D. Shaded Circle Answer: D. Shaded Circle Rationale: In pedigree analysis, a shaded circle is used to represent a female individual who is a carrier for a genetic disorder. 1. A patient has type AB blood. Which of the following genotypes could their parents have? (A) IAIA and IBIB (B) IAi and IBi (C) ii and IAIB (D) IAIA and ii. Answer: B. Rationale: Type AB blood is an example of codominance where both IA and IB alleles are expressed. Parents with IAi and IBi genotypes can produce an offspring with IAIB genotype. 2. In a dihybrid cross between two heterozygous parents (AaBb x AaBb), what is the probability of producing an offspring with the genotype AaBB? (A) 1/16 (B) 1/8 (C) 3/16 (D) 1/4. Answer: C. Rationale: The probability of Aa from one parent is 1/2 and BB from the other parent is 1/4. Multiplying these probabilities gives 1/2 * 1/4 = 1/8, but since there are two ways to achieve AaBB, the probability doubles to 3/16. 3. Which principle explains why alleles for different traits are distributed independently of one another? (A) Principle of Dominance (B) Law of Segregation (C) Law of Independent Assortment (D) Principle of Uniformity. Answer: C. Rationale: Mendel's Law of Independent Assortment states that the alleles of different genes segregate independently of each other during the formation of gametes. 4. If a woman who is a carrier for hemophilia (XHXh) has a child with a man who does not have hemophilia (XHY), what is the probability that their son will have hemophilia? (A) 0% (B) 25% (C) 50% (D) 100%. Answer: C. Rationale: The mother can pass on either the XH or Xh allele, and the father can only pass on the Y chromosome. Therefore, there is a 50% chance their son will inherit XhY and have hemophilia. 5. In pea plants, yellow seeds (Y) are dominant over green seeds (y). What is the expected phenotypic ratio of a cross between two heterozygous yellow-seeded plants (Yy x Yy)? (A) 1:1 (B) 3:1 (C) 9:3:3:1 (D) 1:2:1. Answer: B. Rationale: The cross of Yy x Yy yields a 3:1 ratio of yellow to green seeds, as the dominant allele Y masks the presence of the recessive allele y in the phenotype.