5) The same allele can have a different effect depending on which parent it comes from.

TRUE

6) Hereditary characteristics are transmitted to offspring by genes.

TRUE

7) Alleles may code for alternative expressions of a genetic trait.

TRUE

8) Hemophilia is an X-linked condition caused by a recessive gene.

TRUE

9) Environmentally produced phenotypes that mimic conditions that may be caused by genetic mutation are called phenocopies.

TRUE

10) Most genetic disorders are inherited through dominant genes.

FALSE

11) A Punnett square is a diagram that may be used to figure out the possible combinations of genes for a trait.

TRUE

12) The term lethal dominant gene indicates that the gene causes death only when the individual is homozygous.

FALSE

13) In incomplete dominance, the heterozygote has a phenotype intermediate between that of homozygous-dominant and homozygous-recessive individuals.

TRUE

14) Down syndrome is an example of nondisjunction of chromosomes.

TRUE

15) Normal vision is dictated by autosomal dominant genes.

FALSE

16) Genetic segregation implies that the members of the allele pair determining each trait are distributed to different gametes during mitosis.

FALSE

17) Genetic variation results from the crossing over and exchange of chromosomal parts that occur during meiosis II.

FALSE

18) Small RNAs control the timing of programmed cell death during development.

TRUE

19) Mitochondrial genes are free of errors. As a result, all genetic problems are due exclusively to nuclear genes.

FALSE

20) It is possible for a baby to have type O blood if neither parent is type O.

TRUE

1) How many alleles exist for a given gene? A) always one allele per gene B) only two C) each gene can have a different number of alleles D) two from each parent

C

2) Select the statement that best describes the difference between a gene and an allele. A) Genes code for a single protein or a single trait while an allele can code for many traits or many proteins. B) Genes follow Mendelian patterns of inheritance while alleles follow non-Mendelian patterns of inheritance. C) Alleles are found on chromosomes while genes are independent. D) Genes express a specific trait while alleles are variations of a particular gene that result in the variation we see in a genetic individual trait.

D

3) If a person is homozygous for a particular trait this means ________. A) the person has two dominant alleles for the gene responsible for the trait B) the person will not have a recessive condition C) the person has two identical alleles for the gene responsible for the trait D) the person cannot pass on that trait

C

4) A dominant allele is best defined as ________. A) the healthy allele sometimes referred to as the wild type allele B) the allele that is most frequently expressed in a given population C) the stronger of two matched alleles D) an allele that stops or hides the expression of the other allele

D

5) Recessive alleles are best defined as ________. A) only expresses in present in a double dose B) the least frequently expressed allele in a given population C) a deleterious or disease causing allele D) a weakened or attenuated allele

A

6) Of the different sources of genetic variability which one causes the variation in the combinations of homologs from paternal and maternal linage found within a haploid cell? A) independent assortment B) crossing over C) random fertilization D) mutation

A

7) Of the different sources of genetic variability which one produces the variation in the combinations of alleles on a single chromosome? A) independent assortment B) crossing over C) random fertilization D) mutation

B

8) Of the different sources of genetic variability which one produces the variation seen by the combination of any particular male gamete to any particular female gamete? A) independent assortment B) crossing over C) random fertilization D) mutation

C

9) Of the different sources of genetic variability which on could be defined as permanent, transmissible changes to the DNA coding sequence that are often caused by outside environmental factors? A) independent assortment B) crossing over C) random fertilization D) mutation

D

10) The cleft chin trait follows a dominant-recessive inheritance pattern with cleft chin being the dormant trait. John is heterozygous for a cleft chin as is his wife Betty. John and Betty have three kids all of which have a cleft chins. According to Punnett square prediction what is the likely hood that their next child will have a cleft chin? A) 25% chance the same probability for all subsequent children B) 0% because the three pervious children have cleft chins already C) 100% chance because the mother and father both have cleft chins D) 75% chance the same probability for all subsequent children

D

11) Steven has the dominant tongue rolling phenotype but he does not know his genotype. His wife has the recessive non-tongue rolling trait. If their son cannot roll his tongue this means ________. A) Steven has a heterozygous genotype B) that it is impossible to tell Steven's genotype from this information alone C) Steven has a homozygous dominant genotype D) Steven has a homozygous recessive genotype

A

12) Steven has the dominant tongue rolling phenotype but he does not know his genotype. His wife has the recessive non-tongue rolling trait. If their son can roll his tongue this means ________. A) Steven has a homozygous recessive genotype B) Steven has a heterozygous genotype C) Steven has a homozygous dominant genotype D) that it is impossible to tell Steven's genotype from this information alone

D

13) Two alleles expressing exactly the same information for a trait are designated as ________. A) homozygous B) monogamous C) heterozygous D) hemizygous

A

14) Dominant alleles are so called because under most circumstances they ________. A) code for genes that are never considered lethal B) suppress the expression of other alleles C) code for desired traits only D) code for most phenotypic and genotypic expressions of a trait

B

15) Recessive genes are usually expressed in humans only when ________. A) the organism is in the embryonic stage B) they are coding for skin color C) they are coding for genetic diseases D) both alleles are exactly the same, or homozygous

D

16) Those characteristics that can be determined on superficial inspection of an individual are known as ________. A) polyspermic B) polygenic C) genotypic D) phenotypic

D

17) Is genetic diversity due entirely to inherited genes on the sex chromosomes? A) Yes, because the female has two X chromosomes and the male has only one X chromosome. B) Yes, because genetic diversity is due to the Y influence on the autosomes. C) Yes, because the male has a Y chromosome. D) No, because genetic diversity has nothing to do with the sex chromosomes but is due to crossing-over of chromosomes, independent assortment of chromosomes, and segregation of chromosomes.

D

18) A female infant is born with several hundred oocytes, each one genetically unique. This is due to ________. A) independent assortment and random crossover B) recessive inheritance C) mutation D) chromosome deletion

A

19) In meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cell that produces them. This is one reason for the great variation among humans. What causes this effect? A) chromosome segregation and independent assortment only B) crossing-over and chromosome segregation only C) crossing-over and independent assortment only D) crossing-over, chromosome segregation, and independent assortment

C

20) The reason recessive genetic disorders are more frequent than disorders inherited as dominant is that ________. A) people carrying dominant genetic disorders always die before birth B) recessive genetic disorders are limited to persons of the same ethnicity C) carriers are not eliminated by the disease before passing the defective alleles on to their offspring D) dominant genetic disorders are never expressed in males

C

21) The gene responsible for the condition known as sickle-cell anemia demonstrates ________. A) incomplete dominance B) a recessive genetic disorder C) a dominant genetic disorder D) a sex-linked genetic disorder

A

22) An example of multiple-allele inheritance is ________. A) hair that seems to have several shades of a color B) the appearance of birthmarks on the skin C) the appearance of freckles on the skin D) the ABO blood group

D

23) Which of the following is true concerning environmental influence on genetic expression? A) The only time a gene can be influenced by environmental factors is in the second trimester of pregnancy. B) Drugs and nutrition can alter normal gene expression. C) It is impossible to alter in any way the expression of a gene in humans. D) Environmental factors determine the way in which 90 percent of our genes are expressed.

B

24) Sex chromosomes of a normal male are ________. A) XX B) XY C) YY D) any of these, depending on the father

B

25) A woman has blond hair and brown eyes. This statement is best described as indicating ________. A) genotype B) phenotype C) allelic pairs D) recessive traits

B

26) A chromosomal aberration in which part of a chromosome is lost is known as ________. A) deletion B) translocation C) crossing-over D) inversion

A

27) Inheritance of stature (height) in humans is probably due to ________. A) polymorphism B) polygene inheritance C) incomplete dominance D) polyploidy

B

28) An individual who is heterozygous for a particular trait, yet expresses both alleles of that trait, is an example of ________. A) dominance B) incomplete dominance C) recessive inheritance D) sex-linked inheritance

B

29) Given the information in Figure 29.1, what would be the genotype of the offspring designated by the blank square? A) gg B) GG C) Dg D) Gg

A

30) Given the information in Figure 29.1, what would the genotype ratio be for the offspring? A) 1:1:1:1 B) 1:2:1 C) 1:3 D) 4:0

B

31) Given the information in Figure 29.1, what is the phenotype ratio (assuming C is dominant and there is no incomplete dominance)? A) 1:1:1:1 B) 1:2:1 C) 1:3 D) 4:0

C

32) Given the information in Figure 29.1, if C were an incomplete dominant trait, what would the phenotype ratio be for the offspring? A) 1:1:1:1 B) 1:2:1 C) 1:3 D) 4:0

B

33) ________ is the most common type of fetal testing. A) CVS B) A DNA probe C) Blood chemistry D) Amniocentesis

D

34) Huntington's disease involves ________. A) hypersecretion of growth hormone B) the presence of an extra chromosome C) hyposecretion of thyroxine D) degeneration of the basal nuclei of the brain

D

35) Which of the following statements is true concerning genetic screening? A) Genetic screening is rarely done because it yields very little accurate information. B) Screening can be done only in the first trimester of pregnancy. C) Screening is illegal in over half of the world. D) Screening can be done before conception by carrier recognition or during fetal testing.

D

36) Amy's hand was exposed to X rays. A gene in a skin cell of her hand mutated. This mutant gene will ________. A) not form an exact duplicate of itself when the cell divides B) definitely cause skin cancer C) replicate itself when the cell divides but will not be passed on to Amy's offspring D) replicate itself and be passed on to Amy's children

C

37) The main way a recessive allele would be expressed even when only one copy is present would be ________. A) dominance B) recessive inheritance C) incomplete dominance D) sex-linked inheritance

D

38) A couple whose blood types are A (IAi) and B (IBi) may have a child with which of the following blood types? A) A, B, AB, or O B) AB only C) A or B only D) AB or O only

A

39) Gene mutations in the sex chromosomes of the human would tend to become visibly expressed ________. A) more frequently in females B) more frequently in males C) equally frequently in both sexes D) in neither males or females

B

40) For which of the following are newborn infants not routinely screened at birth? A) PKU B) color blindness C) imperforate anus D) congenital hip dysplasia

B