Genetics
Imagine that you are a rabbit breeder with two purebred rabbits, a male with black fur and a female with tan fur. When you cross your rabbits, all of the \text F_1F1start text, F, end text, start subscript, 1, end subscript kits (baby rabbits) have tan fur. Which trait is dominant, and which is recessive? (Choice A)ABlack fur is dominant, while tan fur is recessive (Choice B) BTan fur is dominant, while black fur is recessive (Choice C)CBoth tan fur and black fur are dominant (Choice D)DNeither tan fur nor black fur is dominant
Tan fur is dominant, while black fur is recessive
DNA base pair. Under normal circumstances, the nitrogen-containing bases adenine (A) and ___________________ pair together, and cytosine (C) and _________________ pair together. The binding of these base pairs forms the structure of DNA .
DNA base pair. Under normal circumstances, the nitrogen-containing bases adenine (A) and thymine (T) pair together, and cytosine (C) and guanine (G) pair together. The binding of these base pairs forms the structure of DNA .
Which statement best describes the relationship between genotype and phenotype? Genotype always completely determines phenotype Phenotype always completely determines genotype Genotype determines phenotype, but with influence from the environment Phenotype determines genotype, but with influence from the environment
Genotype determines phenotype, but with influence from the environment
In RNA, uracil base-pairs with ____________________ and replaces thymine during DNA transcription. Methylation of uracil produces thymine.
In RNA, uracil base-pairs with adenine and replaces thymine during DNA transcription. Methylation of uracil produces thymine. In DNA, the evolutionary substitution of thymine for uracil may have increased DNA stability and improved the efficiency of DNA replication
In the diagram below, what accounts for the green pea seed in the f2 generation? a. On average, 1 out of 4 offspring of heterozygous parents will be homozygous recessive. b)The yellow allele is dominant over the green one. c)The f1 generation parents are homozygous yellow.
a. Since the recessive allele is green, only plants that are homozygous green for this trait will have a green phenotype. The homozygous yellow and the heterozygous ones will all be yellow.
When the genotype consists of a dominant and a recessive allele, the phenotype will be like _________________ allele. a)the dominant b)the recessive c)neither
a. The dominant allele masks the appearance of the recessive one. However, as you will see in the next section of this tutorial, there are some traits for which this simple rule of dominance does not apply.
Mendel believed that the characteristics of pea plants are determined by the: a)inheritance of units or factors from both parents b)inheritance of units or factors from one parent c)relative health of the parent plants at the time of pollination
a. We now call these units genes. Each inherited trait is determined by at least one gene from each parent.
Gregor Mendel was: a)an English scientist who carried out research with Charles Darwin b)a little known Central European monk c)an early 20th century Dutch biologist who carried out genetics research
b. He worked in virtual obscurity during the mid 19th century. Unfortunately, Charles Darwin did not know of Mendel`s work. He was one of the few scientists of that time who might have understood and appreciated Mendel`s huge contribution to science.
Phenotype refers to the ______________________ of an individual. a)genetic makeup b)actual physical appearance c)recessive alleles
b. Phenotype is the observable characteristics, including physical appearance. It results from the genotype and environmental influences. A phenotype includes not only easily measured traits like hair color but also less apparent ones such as blood type.
green --- yellow (parent) Y Y Y Y (f1 gen) Y Y Y G ( 3:1 ratio) (f2 gen) Assuming that both parent plants in the diagram below are homozygous, why would all of the f1 generation have yellow phenotypes? a)because the f1 genotypes are homozygous b)because yellow is dominant over green c)because both parents passed on yellow alleles
b. When there is a genotype that consists of a dominant and a recessive allele, the phenotype generally looks like the dominant one. In this case, yellow is dominant.
Which of the following statements is true about Mendel? a)His discoveries concerning genetic inheritance were generally accepted by the scientific community when he published them during the mid 19th century. b)He believed that genetic traits of parents will usually blend in their children. c)His ideas about genetics apply equally to plants and animals.
c. He gave us the basis for understanding genetic inheritance in all living things, including humans. His realization that we inherit units or genes was the key to it all.
The idea that for any particular trait, the pair of alleles of each parent separate and only one allele from each parent passes to an offspring is Mendel's principle of: a. independent assortment b)hybridization c)segregation
c. This is the definition of the principle of segregation. Stated in other words, genes occur in pairs and during the process of sex cell production, the members of each pair separate so that each sperm and ovum cell receives one member of each pair.
An allele is: a)another word for a gene b)a homozygous genotype c)a heterozygous genotype d)one of several possible forms of a gene
d. An allele is one of two or more alternate forms of a gene. If an individual is homozygous (YY or GG) for a trait, it has inherited the same allele from both parents. If it is heterozygous (YG), it has inherited different alleles for the trait. An allele is one of a pair of genes that appear at a particular location on a particular chromosome and control the same characteristic, such as blood type or color blindness. Alleles are also called alleleomorphs. Your blood type is determined by the alleles you inherited from your parents. gene is the basic unit of heredity that occupies a specific location on a chromosome. Each consists of nucleotides arranged in a linear manner. Most genes code for a specific protein or segment of protein leading to a particular characteristic or function.
1. Factors that control traits are called a. genes. b. purebreds. c. recessives. d. parents. A B C D 2. Scientists call an organism that has two different alleles for a trait a a. hybrid. b. trait. c. purebred. d. factor. A B C D 3. What does the notation TT mean to geneticists? a. two dominant alleles b. two recessive alleles c. at least one dominant allele d. one dominant and one recessive allelle A B C D 4. What does the notation Tt mean to geneticists? a. two dominant alleles b. two recessive alleles c. at least one recessive allele d. one dominant allele and one recessive allelle A B C D 5. What is probability? a. the actual results from a series of events b. the likelihood that a particular event will occur c. the way the results of one event affect the next event d. the number of times a coin lands heads up A B C D 6. What does a Punnett square show? a. all the possible outcomes of a genetic cross b. only the dominant alleles in a genetic cross c. only the recessive alleles in a genetic cross d. all of Mendel's discoveries about genetic crosses A B C D 7. If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that an offspring will have black fur? a. 25 percent b. 50 percent c. 75 percent d. 100 percent A B C D 8. An organism's physical appearance is its a. genotype. b. phenotype. c. codominance. d. heterozygous. A B C D 9. What does codominance mean in genetics? a. Both alleles are dominant. b. Both alleles are recessive. c. The alleles are neither dominant nor recessive. d. Each allele is both dominant and recessive. A B C D 10. What happens during meiosis? a. Each sex cell loses half of its chromosomes. b. Chromosome pairs separate to form new sex cells. c. Each sex cell copies itself to form four new chromosomes. d. Chromosome pairs remain together when new sex cells are formed. A B C D 11. When sex cells combine to produce offspring, each sex cell will contribute a. one fourth of the normal number of chromosomes. b. half the normal number of chromosomes. c. the normal number of chromosomes. d. twice the normal number of chromosomes. A B C D 12. What is a mutation? a. any change that is harmful to an organism b. any change in a gene or chromosome c. any change that is helpful to an organism d. any change in the phenotype of a cell A B C D 13. Which term refers to physical characteristics that are studied in genetics? a. traits b. offspring c. generations d. hybrids A B C D 14. The different forms of a gene are called a. alleles. b. factors. c. masks. d. traits. A B C D 15. Where does protein synthesis take place? a. in the ribosomes in the nucleus of the cell b. on the ribosomes in the cytoplasm of the cell c. in the chromosomes in the nucleus of the cell d. on the chromosomes in the cytoplasm of the cell A B C D 16. What does the notation tt mean to geneticists? a. two dominant alleles b. two recessive alleles c. at least one dominant allele d. one dominant and one recessive allelle A B C D 17. An organism's genotype is its a. genetic makeup b. feather color c. physical appearance d. stem height A B C D 18. Which nitrogen base in RNA is NOT part of DNA? a. adenine b. guanine c. cytosine d. uracil A B C D 19. An organism that has two identical alleles for a trait is a. codominant. b. tall. c. homozygous. d. heterozygous. A B C D 20. A heterozygous organism has a. three different alleles for a trait. b. two identical alleles for a trait. c. only one allele for a trait. d. two different alleles for a trait. A B C D 21. Which of these traits is controlled by a gene with multiple alleles? a. straight hairline b. smile dimples c. widow's peak d. blood type A B C D 22. Which combination of sex chromosomes results in a male human being? a. XX b. YY c. XY d. either XX or YY A B C D 23. Why are sex-linked traits more common in males than in females? a. All alleles on the X chromosome are dominant. b. All alleles on the Y chromosome are recessive. c. A recessive allele on the X chromosome will always produce the trait in a male. d. Any allele on the Y chromosome will be codominant with the matching allele on the X chromosome. A B C D 24. How does a geneticist use pedigrees? a. to create genetic crosses b. to replicate identical strings of DNA c. to prove that sex-linked traits are caused by codominant alleles d. to trace the inheritance of traits over generations of families A B C D 25. What is a pedigree? a. a chart that tracks which members of a family have a particular trait b. a geneticist who studies the inheritance of traits in humans c. a picture of all of the chromosomes in a cell d. an allele passed from parent to child on a sex chromosome A B C D 26. Genetic disorders are caused by a. pedigrees. b. mutations. c. dominant alleles. d. sickle-shaped cells. A B C D 27. Which genetic disorder causes the body to produce unusually thick mucus in the lungs and intestines? a. hemophilia b. Down syndrome c. cystic fibrosis d. sickle-cell disease A B C D 28. Cloning results in two organisms that are a. both adult mammals. b. produced from cuttings. c. genetically similar. d. genetically identical. A B C D 29. Which of these is an example of the benefits of genetic engineering? a. cross-breeding to create disease-resistant crops b. creating human insulin to treat people with diabetes c. analyzing karyotypes and pedigree charts d. growing a new plant from a cutting A B C D 30. No two people have the same DNA, except for a. crime suspects. b. brothers. c. sisters. d. identical twins. A B C D 31. Sex-linked genes are genes on a. the X chromosome only. b. the Y chromosome only. c. the X and Y chromosomes. d. all 23 pairs of chromosomes. A B C D 32. A carrier is a person who has a. one recessive and one dominant allele for a trait. b. two recessive alleles for a trait. c. two dominant alleles for a trait. d. more than two alleles for a trait.
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The idea that different pairs of alleles are passed to offspring independently is Mendel's principle of: unit inheritance b)segregation c)independent assortment
this is a definition of his principle of independent assortment. Stated in other words, the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible.