Genetics Test 2 Ch. 2

Question 1

1) Genetic crosses in which F1 plants heterozygous for a given allele are crossed to generate a 3:1<br></br>phenotypic ratio in the F2 generation are known as ________.<br></br>A) test crosses<br></br>B) dihybrid crosses<br></br>C) reciprocal crosses<br></br>D) monohybrid crosses<br></br>E) replicate crosses

Answer 1

Answer: D

Question 2

2) In peas, the smooth allele is dominant over the wrinkled allele. A plant with round peas was crossed to a plant with wrinkled peas and all of the resulting plants had smooth peas. What are the genotypes of the parents in this cross?<br></br>A) Rr × Rr B) rr × rr C) RR × Rr D) Rr × rr E) RR × rr

Answer 2

Answer: E

Question 3

3) In peas, the yellow allele is dominant over the green allele. A plant with yellow peas was crossed toa plant with green peas. The resulting plants were 50% yellow and 50% green. What are the genotypes of the parents in this cross?<br></br>A) yy × yy<br></br> B) Yy × yy <br></br>C) YY × yy <br></br>D) Yy × Yy <br></br>E) YY × Yy

Answer 3

Answer: B

Question 4

4) What genotypic ratio would you expect to observe among the progeny of a monohybrid cross?<br></br>A) 3:1 <br></br>B) 1:2:1 <br></br>C) 1:3:2:1 <br></br>D) 1:3 <br></br>E) 9:3:3:1

Answer 4

Answer: B

Question 5

5) You count 1000 F2 seeds from a monohybrid cross. How many seeds do you expect to display the) dominant phenotype?<br></br>A) 750 <br></br>B) 1000 <br></br>C) 0 <br></br>D) 500 <br></br>E) 250

Answer 5

Answer: A

Question 6

6) Assuming independent assortment, what phenotypic ratio would you expect to see if an individual 6) with the genotype RrGg is self- crossed?<br></br>A) 9:3:3:1

Answer 6

Answer: A

Question 7

7) In peas, axial (A) flower position is dominant to terminal (a), tall (L) is dominant to short (l), and yellow (Y) is dominant to green (y). If a plant that is heterozygous for all three traits is allowed to self- fertilize, how many of the offspring would show the dominant phenotype for all three traits?<br></br>A) 3/64 <br></br>B) 32/64 <br></br>C) 27/64 <br></br>D) 9/64 <br></br>E) 64/64

Answer 7

Answer: C

Question 8

8) In peas, axial (A) flower position is dominant to terminal (a), and tall (L) is dominant to short (l). If a plant that is heterozygous for both traits is allowed to self- fertilize, how many of the offspring would also be heterozygous for both traits?<br></br>A) 1/8 B) 1/4 C) 3/16 D) 9/16 E) 1/16

Answer 8

Answer: B

Question 9

9) What phenotypic ratio would you expect as a result of a test cross between two individuals where one that is homozygous recessive for alleles at two independent loci?<br></br>A) 3:1 B) 1:2:1 C) 9:3:3:1 D) 1:1:1:1 E) 9:4:2:1

Answer 9

Answer: D

Question 10

10) If a plant with purple, axial flowers and green, inflated pods is heterozygous for all four genes, how many different types of gametes can it produce?<br></br>A) 4 B) 16 C) 1 D) 8 E) 9

Answer 10

Answer: B

Question 11

11) In Guinea pigs, short hair (S) is dominant over long hair (s), rough coat (R) is dominant over) smooth coat (r), and black hair (B) is dominant over white hair (b). Which of the following individuals could produce these (and only these) four possible gametes: SRb, Srb, sRb, srb.<br></br>A) SsRrbb B) SSRrBb C) SSRRbb D) ssRrBB E) SsRrBb

Answer 11

Answer: A

Question 12

12) The gene L determines hair length in rabbits. The gene B determines hair color. A rabbit with long, black hair is crossed to a rabbit with short, white hair. All the offspring have long, black hair. What are the genotypes of the parents?<br></br>A) LLBB × llbb<br></br>B) Llbb × llBb<br></br>C) LlBb × LlBb<br></br>D) LlBb × llbb<br></br>E) Impossible to determine from the information given

Answer 12

Answer: A

Question 13

13) In rabbits, long hair and black fur are produced by the dominant alleles L and B, which assort independently. The genotype ll produces short hair and the genotype bb produces white fur. A cross between a male with short, black fur and a female with long, white fur produces four offspring with short, black fur, four offspring with long, white fur, four offspring with short, white fur, and four offspring with long, black fur. What are the genotypes of the parents?<br></br>A) LlBb × LlBb <br></br>B) B) LLBB × llbb <br></br>C) C) llBb × Llbb<br></br>D) llBB × LLbb<br></br>E) Impossible to determine from the information given.

Answer 13

Answer: C

Question 14

14) A couple has four children. What is the probability that they have four boys? <br></br>A) 1/2 B) 1/16 C) 1/4 D) 1/32 E) 1/8

Answer 14

Answer: B

Question 15

15) By convention, when an OBSERVED experimental outcome has a probability of occurrence of lessthan 5% (<0.05), the experimental results are considered to be ________.<br></br>A) not significant<br></br>B) statistically significant and different from the expected outcome<br></br>C) less than one standard deviation from the mean<br></br>D) within normal expected range E) equal to the mean

Answer 15

Answer: B

Question 16

16) The statistical interpretation of a chi- square value is determined by identifying the ________. <br></br>A) joint probability<br></br>B) average C) P value<br></br>D) mean<br></br>E) degrees of freedom

Answer 16

Answer: C

Question 17

17) The P value is a quantitative expression of the probability that the results of another experiment of the same size and structure will DEVIATE FROM EXPECTED RESULTS AS MUCH AS OR MORE THAN BY CHANCE. The greater the difference between observed and expected results of an experiment, ________.<br></br>A) the lower the Λ2 value and the lower the P value<br></br>B) the lower the Λ2 value and the greater the P value<br></br>C) the greater the Λ2 value; but the P value is unaffected<br></br>D) the greater the Λ2 value and the greater the P value E) the greater the Λ2 value and the lower the P value

Answer 17

Answer: E

Question 18

18) Humans have a gene, T, that is involved in muscle formation of the tongue. Individuals homozygous for one allele can roll their tongues, while individuals homozygous for the other allele cannot. If both parents can roll their tongues, but their child cannot, what can be said about the mode of inheritance?<br></br>A) The parents were both homozygous, but the child was heterozygous.<br></br>B) Tongue rolling is recessive, and both parents were heterozygous (Tt).<br></br>C) Tongue rolling is recessive.<br></br>D) Tongue rolling is dominant.<br></br>E) Tongue rolling is dominant, and both parents were heterozygous (Tt).

Answer 18

Answer: E

Question 19

28) In 1997, a gene called Le was discovered by two research groups led by David Martin and Diane Lester. Allelic variation in the Le gene, which controls elongation of the plant stem between branches, is responsible for which trait in peas?<br></br>A) yellow and green pod color<br></br>B) inflated and constricted pod shape<br></br>C) axial and terminal flower position<br></br>D) tall and short plant height<br></br>E) purple and white flowers

Answer 19

Answer: D

Question 20

29) Mendel performed numerous controlled genetic crosses to obtain strains that consistently) produced a single phenotype without variation. What are these strains that consistently produce the same phenotype called?

Answer 20

Answer: pure- breeding or true- breeding strains

Question 21

30) In a test cross, a pure- breeding plant is crossed with a plant suspected to be heterozygous (Aa). What is the genotype of the pure- breeding plant?

Answer 21

Answer: aa

Question 22

31) Why did Mendel cut off the nascent anthers during the process of artificial cross- fertilization?

Answer 22

Answer: to prevent self- fertilization or to prevent uncontrolled crosses

Question 23

32) In some of Mendel’s experiments, a cross in which one plant provides the pollen and another with the same genotype provides the egg is followed be another cross in which the first plant provides the egg while the second provides the pollen. During his experiments, these ________ crosses produced identical results.

Answer 23

Answer: reciprocal

Question 24

33) What simple type of cross that investigates the inheritance of only one trait could be used to illustrate Mendel’s law of segregation?

Answer 24

Answer: monohybrid cross

Question 25

34) A cross between a short pea plant and a tall pea plant results in a 1:1 genotypic AND phenotypic ratio in the offspring. What are the genotypes of the parent plants?

Answer 25

Answer: Ss × ss (heterozygous × homozygous recessive)

Question 26

35) The law of independent assortment predicts that crossing of dihybrid F1 plants to one another would produce nine genotypes in a ________ ratio among F2 progeny.

Answer 26

Answer: 9:3:3:1

Question 27

36) What is the probability of rolling one six- sided die and obtaining a 1 or a

Answer 27

Answer: 1/6 + 1/6 = 2/6 = 1/3

Question 28

37) What is the probability of rolling one six- sided die and obtaining any number but 6?

Answer 28

Answer: 1 - 1/6 = 5/6

Question 29

38) What is the probability of rolling two six- sided dice and obtaining two 4’s?

Answer 29

Answer: 1/6 × 1/6 = 1/36

Question 30

39) What is the probability of rolling two six- sided dice and obtaining at least one 3?

Answer 30

Answer: Probability of die 1 being a 3 and die 2 not: 1/6 × 5/6 = 5/36<br></br>Probability of die 2 being a 3 and die 1 not: 1/6 × 5/6 = 5/36<br></br>Probability of die 1 and 2 being a 3: 1/6 × 1/6 = 1/36<br></br>Probability of any of these possibilities = addition rule: 5/36 + 5/36 + 1/6 = 11/36

Question 31

40) What is the probability of rolling two six- sided dice and obtaining an odd number on at least one die?

Answer 31

Answer: 9/36 + 9/36 + 9/36 = 27/36 = 3/4<br></br>Probability of rolling odd number the first die only = 3/6 (odd) × 3/6 (even) = 9/36<br></br>Probability of rolling odd number the second die only = 3/6 (even) × 3/6 (odd) = 9/36<br></br>Probability of rolling odd number both dice = 3/6 (odd) × 3/6 (odd) = 9/36<br></br>Probability of any one of these three possible scenarios = addition rule

Question 32

41) Geneticists must be able to compare the outcomes they obtain in their experiments to the outcomes that might be expected to occur. Which test would they use to confirm that the difference between observed and expected outcomes could be attributed to chance?

Answer 32

Answer: chi- square test

Question 33

42) If an affected individual is born to parents who are unaffected, what is the likely mode of 42) inheritance?

Answer 33

Answer: autosomal recessive

Question 34

45) A ratio of 9:3:3:1 is expected among the F2 progeny of a dihybrid cross as a result of ________ of alleles at two loci.

Answer 34

Answer: independent assortment

Question 35

46) In a cross between individuals who are both heterozygous (carriers) for a recessive disease, such as albinism, you would like to determine the risk of one or more children inheriting the recessive phenotype. ________ probability can be used to calculate the probability of a particular combination of events that each have two alternative outcomes?

Answer 35

Answer: Binomial

Question 36

47) You have self- fertilized a plant with round seeds that is heterozygous, and you want to determine what proportion of the offspring will be dominant and true breeding. ________ probability can be used to calculate the probability of obtaining a particular outcome when specific information about that outcome modifies the probability calculation?

Answer 36

Answer: Conditional

Question 37

48) The P value is dependent on the number of ________, which is equal to the number of independent variables in an experiment.

Answer 37

Answer: degrees of freedom (df)