chapter 15 reveiw bio111

1. The chromosome theory of inheritancestates that _____.

genes occupyspecificpositions onchromosomes

2. Why did Morgan choose Drosophilafor his genetics experiments?

They have a longgeneration time.A single matingcan producemany offspring.They have alarge number ofchromosomes.Drosophilachromosomescan be easilydistinguishableunder a lightmicroscope.Both the secondand fourthanswers arecorrect.

3. Wild type refers to _____. the mostcommonphenotypethought to befound in thenaturalpopulation

4. Which of the following results ofThomas Hunt Morgan's experimentswith white-eyed mutant flies wasunexpected in light of Mendeliangenetics? (

Among the F2progeny, onlymales had whiteeyes. All of thefemales had redeyes.

5. What is the probability that a male willinherit an X-linked recessive allelefrom his father?

0%

6. In an X-linked, or sex-linked, trait, it isthe contribution of _____ thatdetermines whether a son will displaythe trait.

The mother

7. If a mother is heterozygous for arecessive sex-linked trait and herhusband has the dominant allele,which one of the following is true aboutthe probabilities for their children?

Half of theirsons will havethe recessivetrait.

8. In werewolves (hypothetically), pointyears (P) are dominant over round ears(p). The gene is on the X chromosome.(Sex determination in werewolves is thesame as for "other" humans.) A certainfemale werewolf has pointy ears eventhough her father had round ears. Whatpercentage of her sons will have roundears if she mates with a werewolf withround ears?

50%

9. A woman is red-green color-blind. Whatcan we conclude, if anything, about herfather?

He is red-green color-blind.

10. A woman is a carrier for red-green colorblindness, a sex-linked trait. Her husbandis normal (not color-blind) for this trait.What are the chances that their newborndaughter will be red-green color-blind?

0%

11. Duchenne muscular dystrophy is causedby a sex-linked recessive allele. Its victimsare almost invariably boys, who usuallydie before the age of 20. Why is thisdisorder almost never seen in girls?

To expressan X-linkedrecessiveallele, afemale musthave twocopies of theallele.

12. Hemophilia is a sex-linked disorder. Thedaughter of a father with hemophilia anda carrier mother has a _____ probabilityof having hemophilia.

50%

13. Queen Victoria was a carrier of arecessive sex-linked allele for hemophilia.Which one of the following possibilitiescould explain the presence of thehemophilia allele in her genotype?

Either hermother wasa carrier orher fatherhadhemophilia

14. In a certain fish, fin rays (supportingstructures for the fins) can be either bonyor soft in adult fish. Sex linkage in a fish issimilar to that in humans. What evidencewould most strongly support the idea thatthe ray locus is on the X chromosome?

Matings ofsoft raymales andbony rayfemales givedifferentresults fromthe matingsof bony raymales andsoft rayfemales.

Chapter 15 reveiw bio111Study online at quizlet.com/_4tns1

15. A genetic defect in humans results inthe absence of sweat glands in the skin.Some men have this defect all over theirbodies, but in women it is usuallyexpressed in a peculiar way: A womanwith this defect typically has smallpatches of skin with sweat glands andother patches without sweat glands. Inwomen, the pattern of sweat-glanddistribution can best be explained by_____.

X chromosomeinactivation

16. With a microscope, you examine somesomatic cells from a woman and noticethat each nucleus has two Barr bodies.What can you infer about the sexchromosomes in this individual?

She is XXX

17. During meiosis, homologouschromosomes sometimes "sticktogether" and do not separate properly.This phenomenon is known as _____.

nondisjunction

18. n Klinefelter syndrome, individuals arephenotypically male, but they are talland thin, have a female-likedevelopment of the hips and breasts,and have testes that remain in theabdomen instead of descending into thescrotum. The cells of Klinefelterindividuals have two X chromosomesand one Y (they are XXY instead ofXY). That is, Klinefelter syndrome isa(n) _____. (Concept 15.4E-Book)

aneuploidy

19. Cells that have more than two completesets of chromosomes are termed_____.

polyploidy

20. _____ is usually less severe than_____, and _____ species have beenobserved in plants, fish, amphibians,and even mammals.

Polyploidy ...aneuploidy ...polyploid

21. Gene A is normally found onchromosome number 15 in humans. Ifamniocentesis reveals fetal cellscontaining gene A on chromosome 17,but not on 15, the best explanationwould be that _____.

translocationoccured

22. The exchange of segments betweennonhomologous chromosomes is called_____

translocation

23. Why are individuals with an extrachromosome 21, which causes Downsyndrome, more numerous thanindividuals with an extra chromosome3 or chromosome 16?

Extra copies ofthe otherchromosomesare probablyfatal to thedevelopingembryo.

24. When a person has Downsyndrome, he or she has an extrachromosome 21. Therefore, Downsyndrome is a kind of _____ andresults from _____.

aneuploidy ...nondisjunction ofchromosome 21during meiosis I

25. Which one of the following is theonly known viable humanmonosomy?

XO

26. Which type of chromosomalalteration is responsible for thedisorder cri du chat?

deletion

27. Which of the following statementsabout genomic imprinting isincorrect?

It silences theexpression ofcertain genes infemales, but not inmales.

28. Both chloroplasts andmitochondria _____.

carry extranucleargenes

29. It is proposed that a certaindisorder affecting the inner ear iscaused by mitochondrial DNA.Which of the following observationswould be the most decisive evidenceagainst this idea?

Fathers with thedisorder pass it onto all theirchildren, butmothers with thedisorder do notpass it along.