Chap 19

Question 1

1) What is a locus?

Answer 1

1. A locus is the location of an allele on a chromosome

Question 2

2) Approximately how many genes do humans possess?

Answer 2

2. 21,500

Question 3

3) What is each version of a gene called?

Answer 3

3. allele

Question 4

4) What is the condition referred to if two copies of a gene are identical alleles?

Answer 4

4. homozygous

Question 5

5) What is the condition referred to if two copies of a gene are different alleles?

Answer 5

5. heterozygous

Question 6

6) What is an allele called when that allele’s effect on a trait masks that of an allele paired with it?

Answer 6

6. dominant

Question 7

7) When an allele’s effect on a trait is masked by that of an allele paired with it, what is the second allele referred to as?

Answer 7

7. recessive

Question 8

8) What is the genotype AA referred to as?

Answer 8

8. homozygous dominant

Question 9

9) What is the genotype aa referred to as?

Answer 9

9. homozygous recessive

Question 10

10) What is the genotype Aa referred to as?

Answer 10

10. heterozygous

Question 11

11) What are the alleles an individual inherits called?

Answer 11

11. genotype

Question 12

12) What are observable functional or physical traits called?

Answer 12

12. Phenotype

Question 13

13) What is the most accurate description of an organism with genotype AaBb ?

Answer 13

13. Dihybrid

Question 14

14) Gene A occurs on chromosome 5, gene B is on chromosome 21. Therefore, these two parts of the chromosomes can NOT be

Answer 14

14. Linked

Question 15

15) If two parent organisms have different alleles for a gene that an experimenter wants to test, what test will he or she perform?

Answer 15

15. Test cross

Question 16

16) What gametes will a parent with the genotype CC will produce?

Answer 16

16. C

Question 17

17) When homologues separate into different gametes after meiosis I, the genes of each pair separate as well. What is this principle called?

Answer 17

17. Segregation

Question 18

18) The principle of segregation applies most specifically to events occurring in preparation of what?

Answer 18

18. gametes

Question 19

19) What does the theory of segregation deal with?

Answer 19

19. explains the behavior of a pair of alleles during meiosis.

Question 20

20) If R is dominant to r, the offspring of the cross of RR with rr will have what phenotype?

Answer 20

20. the same phenotype as the RR parent

Question 21

21) If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what phenotypes of offspring will be produced?

Answer 21

21. all tall

Question 22

22) If all offspring of a cross have the genotype Aa, what would the parents of the crosses most likely be?

Answer 22

22. AA x aa

Question 23

23) What is a graphic tool used to determine the probable outcome of genetic crosses called?

Answer 23

23. Punnett square

Question 24

24) When the first generation parents are homozygous for different alleles, a 3:1 phenotype ratio will most likely appear in which generation of offspring?

Answer 24

24. F2

Question 25

25) In a monohybrid cross, what kind of genes "disappear" in the F1 generation?

Answer 25

25. recessive

Question 26

26) What is the F2 phenotypic ratio of a monohybrid cross?

Answer 26

26. 3:1

Question 27

27) In the cross Cc x Cc, gametes have a ____ chance of receiving either allele.

Answer 27

27. 50 x 50

Question 28

28) In a Punnett square, what do the letters within the little boxes represent?

Answer 28

28. offspring genotypes

Question 29

29) If short hair (L) is dominant to long hair (l), then to determine the genotype of a short-haired animal it should be crossed with what genotype animal?

Answer 29

29. ll

Question 30

30) When an individual with an unknown genotype is crossed with an individual that is homozygous recessive for the trait being studied, what is the procedure called?

Answer 30

30. testcross

Question 31

31) The results of a testcross reveal that all offspring resemble the parent being tested. What is the genotype of the parent

Answer 31

31. homozygous

Question 32

32) What does a testcross involve?

Answer 32

32. an F1 hybrid and an organism that is homozygous recessive for that trait

Question 33

33) If all the offspring of a testcross are alike and resemble the organism being tested, then what is the genotype of that parent?

Answer 33

33. homozygous dominant

Question 34

34) Assume short hair (L) is dominant to long hair (l), and black hair (B) is dominant to brown (b). If you found a black, short-haired animal, you could determine its genotype by crossing it to an animal with what genotype?

Answer 34

34. ll bb

Question 35

35) If all the offspring of a cross had the genotype Aa Bb, what would the parents of the cross most likely be?

Answer 35

35. both AA BB x aa bb and AA bb x aa BB

Question 36

36) When considering non-related traits, the fact that they may be inherited individually without any effect on one another is known as??

Answer 36

36. independent assortment

Question 37

37) A given chromosome and its genes may end up in any of how many gametes?

Answer 37

37. 4

Question 38

38) What is the principle of independent assortment?

Answer 38

38. each hereditary unit on one chromosome is inherited separately from hereditary units on other chromosomes

Question 39

39) In cocker spaniels, black coat color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). If two dihybrids (Bb Ss) were crossed, what would the most common phenotype be?

Answer 39

39. black and solid

Question 40

40) In cocker spaniels, black coat color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). A cross of Bb Ss with bb ss would produce what phenotypic ratio?

Answer 40

40. 1:1:1:1

Question 41

41) If a child has blood type AB, can one of the parents have type O blood?

Answer 41

41. no

Question 42

42) Blood types (A, B, and O) are controlled by what kind of gene?

Answer 42

42. multiple alleles

Question 43

43) The ABO blood types have how many different genotypes?

Answer 43

43. 6

Question 44

44) If a child has blood type O, he or she could NOT have been produced by which set of parents?

Answer 44

Type AB mother and type O father

Question 45

45) How many different alleles for ABO blood types are in the total human population?

Answer 45

45. 3

Question 46

46) If a woman of blood type A has a child of blood type O, what blood type(s) can the father have?

Answer 46

46. blood types A, B, or O, but not AB

Question 47

47) If one parent has blood type A and the other parent has blood type B, then what are the possible blood types of their children?

Answer 47

47. A, B, AB, and O

Question 48

48) What is a gene that has three or more alleles called?

Answer 48

48. multiple allele system

Question 49

49) What is it called when both alleles for a particular trait are expressed at the same time?

Answer 49

49. codominance

Question 50

50) Which is easier to establish in a pure-breeding population, a dominant or a recessive gene?

Answer 50

50. Recessive

Question 51

51) Tall (D) is dominant to dwarf (d). Give the F2 genotypic and phenotypic ratios of a cross between a pure-breeding, tall plant and a pure-breeding, dwarf plant.

Answer 51

51. 1 DD, 2 Dd, 1 dd; 3 tall, 1 dwarf

Question 52

52) If wire hair (W) is dominant to smooth hair (w) and you find a wire-haired puppy, how would you determine its genotype by a genetic breeding experiment? Give both the genotype and phenotype involved with the cross with the unknown.

Answer 52

52. Smooth hair, ww