Chromosomes and Phenotype Complex patterns of Inheritance Gene Linkage Human Genetics and Pedigrees Actual Test Questions

Question This individual does not show the trait, but is able to pass on the disease- causing allele to its offspring.

Answer 1 – 10 Carrier

Question Genes that are located on the X or y chromosome, sometimes called the sex chromosomes.

Answer 1 – 20 Sex-linked genes

Question Most of the traits expressed in a person’s phenotype are determined by __________ genes.

Answer 1 – 30 Autosomal

Question In mammals, the expression of sex-linked genes in females is different than genes on other chromosomes, because one of the chromosomes is randomly turned off.

Answer 1 – 40 X chromosome inactivation

Question Genes found on the y chromosome of mammals are responsible for this.

Answer 1 – 50 Development of male offspring and possibly male characteristics

Question Two nine o’clock flowers, one is homozygous red and the other is homozygous white, which will create all offspring in the F1 generation that are pink in color. This is an example of this type of inheritance, because it creates a third distinct phenotype.

Answer 2 – 10 Incomplete dominance

Question When both alleles of a gene are expressed completely in the heterozygous individual– neither allele is dominant nor recessive.

Answer 2 – 20 Codominance

Question Human height, human skin color, hair color, eye color, foot size, hand size are all examples of this type of inheritance pattern.

Answer 2 – 30 Polygenic traits

Question Blood type in humans is an example of these two different type of inheritance patterns: _______________ AND ________________.

Answer 2 – 40 Codominance AND multiple alleles

Question In Labrador retrievers, coat color can be black, brown, or golden. One gene for coat color will cause a different gene for coat color to not be fully expressed, causing the lighter colors to show in the phenotype. Albinism is another example of this inheritance pattern.

Answer 2 – 50 Epistasis

Question Thomas Hunt Morgan concluded from his research on fruit flies that ______________ genes are found on the same ______

Answer 3 – 10 Linked genes are found on the same chromosome

Question The probability that two genes on a chromosome will be inherited together is related to the distance between them. Thus… The ______________ two genes are on the same chromosome, the _________ likely they will be inherited together.

Answer 3 – 20 The closer two genes are to each other on the same chromosome, the more likely the genes will be inherited together. OR the farther apart two genes are on the same chromosome, the less likely the two genes will be inherited together.

Question Complete a linkage map based on the following cross-over percentages for three gene pairs: A to C = 4%, B to C = 12% and A to B = 8%.

Answer 3 – 30 The order would be B – A – C A is found in between B and C as it is only 4 map units away from B, while B is 12 map units away from C which is the furthest relative distance. The order could also go C – A – B as a mirror image of the data.

Question Thomas Hunt Morgan also concluded that during meiosis the ____________, not the _______________, assort independently, which is truly an example of Mendel’s law of independent assortment.

Answer 3 – 40 The Chromosomes, not the genes, assort independently during meiosis.

Question Morgan also concluded that chromosomes must exchange homologous genes during meiosis, and he completed this research by studying the fruit fly, which goes by this scientific name.

Answer 3 – 50 Drosophila melangaster

Question Much of what we know about single- gene traits in humans is the result of studying this.

Answer 4 – 10 Genetic disorders

Question What is the most likely method of inheritance for the following pedigree: (autosomal dominant, autosomal recessive, or sex-linked recessive)

Answer 4 – 20 Dimples are inherited as autosomal recessive, as they are found just as much in females as males (autosomal), and the trait can skip a generation (recessive)

Question When scientist want to determine if a portion of a homologous chromosome pair is missing, or if there is an extra homologous chromosome, a scientist would most likely use this picture of all of the chromosomes in a cell.

Answer 4 – 30 Karyotype

Question Jim is a colorblind male whose father is also colorblind. Jim’s mom has normal vision. Jim can certainly point to his colorblind Dad for his colorblindness – why?

Answer 4 – 40 No, Jim got his X allele from his mother, not his father – the reason Jim is a male is because his y came from his Dad. The colorblind allele had to have been inherited from Jim’s mother, and she must be a carrier for colorblindness.

Question Give the genotype for both of the two children found at the bottom of this pedigree: (remember to first determine if how this pedigree is inherited – is it autosomal dominant, autosomal recessive, or sex-linked recessive)

Answer 4 – 50 The pedigree shows a sex-linked recessive disorder, and the daughter would be either X A X a or X A X A and the son would be X a y

Question A person with A and B alleles for blood type will have what antigens on their red blood cells? A. A antigens B. B antigens C. AB antigens D. O antigens

Answer 5 – 10 Both A and B antigens found on their red blood cells

Question An individual that has three of the number 21 chromosome has this disorder. a.Boy-in-the-bubble disease b.Color blindness c.Down syndrome d. Hemophilia

Answer 5 – 20 Down Syndrome occurs when there is an extra 21 st chromosome

Question Someone who is heterozygous for the alleles will not have the disease, but is a ___________. a.carrier b.dominant c.recessive d.sex-linked

Answer 5 – 30 a.carrier

Question Which of the following is not an outcome of the environment modifying a phenotype ? a.the changing of the color of an animal’s fur as the temperature changes b.the increased intelligence of a person who attended school for many years c.the very short stature of a kind of tree that grows at a high altitude in comparison with the same kind of tree growing at a lower altitude d.the pink-flowered snapdragons that result from crosses between red-flowered and white-flowered snapdragon plants

Answer 5 – 40 d.the pink-flowered snapdragons that result from crosses between red-flowered and white-flowered snapdragon plants

Question What antibodies could be found in the plasma of an individual with blood type A? a.Anti-Ac.Anti-A and Anti-B b.Anti-Bd.None

Answer 5 – 50 b.Anti-B