Question

1. The following diagram shows the genetic map for a chromosome.

A B C D

10cM 5cM 40cM

If a diploid female heterozygous for A and D (A D//a d) is testcrossed to a homozygous recessive male (a d/a d), what percent of the progeny are predicted to have the genotype A d/a d?

A. 100

B. 75

C. 50

D. 25

E. Can’t be determined

2. Yellow body (y), vermillion eye color (v) and miniature body (m) are recessive X-linked traits in Drosophila. The order of the genes on the chromosome is y-v-m. The following cross is performed: y v m (female) X y v m (male) y+ v+ m+ Y The map distances shown below were generated using 1000 male progeny. y-v - 32.0 cM; y-m - 34.3 cM; v-m - 4.0 cM Which of the following statements is FALSE?

A. Twenty of the progeny flies had red eyes and miniature bodies.

B. All of the progeny flies that had vermillion eyes and miniature bodies were also yellow.

C. Recombinant chromosomes present in the progeny flies were generated in the female.

D. The y-m distance is less than the sum of the y-v and v-m intervals because of undetected twostrand double crossovers.

E. The genes for yellow body (y) and vermillion eye color (v) are linked

. 3. A yeast diploid heterozygous for four different genes on Chromosome III, MAT, HIS4, THR4 and LEU2, was put through meiosis and the map distances between different gene pairs was determined by tetrad analysis with the following results: THR4-LEU2 35 cM; MAT-LEU2 16 cM; HIS4-MAT 37 cM; LEU2-HIS4 23 cM; MAT-THR4 16 cM What is the order of the genes on the chromosome?

A. HIS4-LEU2-MAT-THR4

B. HIS4-LEU2-THR4-MAT

C. THR4-HIS4-LEU2-MAT

D. LEU2-MAT-THR4-HIS4

E. LEU2-THR4-HIS4-MAT

4. In the Hfr X Fcross shown below, the pyr + gene from the Hfr strain enters the recipient cells five minutes after the cells are mixed together to allow mating. At this time, no met+ , xyl+ , tyr+ , arg + , his+ or mal+ recombinants are observed. Hfr pyr + met+ xyl++ tyr+ arg + his++ mal++ x F- pyr - metxyltyrarg - his- mal- (NO ORDER IS IMPLIED) The mating is allowed to proceed for 30 minutes and then pyr + recombinants are selected on the appropriate medium. The pyr + recombinants are then screened for the presence of other markers donated from the Hfr strain. These markers are observed in the following frequencies: Percent of pyr + colonies met+ 32 xyl+ 94 tyr+ 7 arg + 59 his+ 0 mal+ 71 What is the order of the genes?

A. origin- pyr-his-tyr-met-arg-mal xyl

B. origin- xyl-mal-arg-met-tyr-his-pyr

C. origin- pyr-xyl-mal-arg-met-tyr-his

D. origin- his-tyr-met-arg-mal xyl-pyr

E. origin- pyr-met-xyl-tyr-arg-his-mal

5. For two alleles at frequencies p and q in a population at Hardy-Weinberg equilibrium, which of the following statements is most likely to be TRUE?

A. When p = q, all individuals in the population are heterozygous.

B. When p = q, no individuals in the population are heterozygous.

C. When p = 1, half of the individuals in the population are heterozygous.

D. When p = 0, all individuals in the population are heterozygous

E. When p = 0.5, half of the individuals in the population are heterozygous

Answer 1

QUESTION 1