1. What does genetic linkage refer to?
A. Random assortment of genes
B. Genes located on different chromosomes
C. Genes inherited together due to proximity on the same chromosome
D. Mutations in linked genes
Answer: C
2. Which scientist is credited with the discovery of genetic linkage?
A. Gregor Mendel
B. Thomas Hunt Morgan
C. Watson and Crick
D. Alfred Sturtevant
Answer: B
3. Recombination frequency between two genes is calculated as:
A. The ratio of parental phenotypes
B. The ratio of recombinant offspring to total offspring
C. The ratio of total offspring to parental offspring
D. The ratio of linked genes to unlinked genes
Answer: B
4. What is the maximum recombination frequency observed?
A. 0%
B. 25%
C. 50%
D. 100%
Answer: C
5. A recombination frequency of 50% indicates that:
A. Genes are linked
B. Genes are unlinked or on different chromosomes
C. Genes are located close together
D. Genes are completely dependent
Answer: B
6. What is a genetic map?
A. A diagram of a physical chromosome
B. A representation of gene positions based on recombination frequencies
C. A sequence of nucleotide bases
D. A catalog of all alleles
Answer: B
7. The unit of genetic distance is:
A. Centimorgan (cM)
B. Megabase (Mb)
C. Nanometer (nm)
D. Base pair (bp)
Answer: A
8. Who developed the first genetic map?
A. Gregor Mendel
B. Watson and Crick
C. Alfred Sturtevant
D. Hugo de Vries
Answer: C
9. If two genes are 10 cM apart, their recombination frequency is:
A. 10%
B. 20%
C. 50%
D. 100%
Answer: A
10. Linkage is more likely when:
A. Genes are on different chromosomes
B. Genes are far apart on the same chromosome
C. Genes are close together on the same chromosome
D. Genes are on mitochondrial DNA
Answer: C
11. A test cross involves:
A. Crossing homozygous recessive individuals
B. Crossing heterozygous individuals with homozygous recessive individuals
C. Crossing two dominant homozygotes
D. Self-pollination
Answer: B
12. What is the significance of crossover events?
A. Prevents genetic variation
B. Produces recombinant offspring
C. Eliminates genetic linkage
D. Causes chromosome breakage
Answer: B
13. Which organism did Morgan use for his linkage experiments?
A. Pea plants
B. Mice
C. Drosophila melanogaster
D. Bacteria
Answer: C
14. What does a genetic map distance of 1 cM indicate?
A. 1% recombination frequency
B. 10% recombination frequency
C. 1 base pair apart
D. 10 base pairs apart
Answer: A
15. Double crossovers are:
A. Very common events
B. Rare events
C. Indicative of tightly linked genes
D. Indicative of unlinked genes
Answer: B
16. What factor decreases the accuracy of genetic maps?
A. High recombination frequency
B. Low recombination frequency
C. Double crossovers
D. Parental inheritance
Answer: C
17. Linkage groups are:
A. Groups of chromosomes
B. Groups of linked genes
C. Groups of alleles
D. Groups of recombinants
Answer: B
18. Which of the following increases recombination frequency?
A. Close proximity of genes
B. Genes located far apart
C. Crossing over in mitosis
D. Absence of linkage
Answer: B
19. The presence of three or more linked genes is referred to as:
A. Trihybrid cross
B. Multiple linkage
C. Polygenic inheritance
D. Linkage group
Answer: D
20. Which of the following is used to determine gene order?
A. Test cross
B. Dihybrid cross
C. Three-point test cross
D. Monohybrid cross
Answer: C
21. Why are recombination frequencies not always additive?
A. Double crossovers reduce observed recombination rates
B. Linkage disrupts recombination
C. Recombination is random
D. Gene mutations interfere
Answer: A
22. What is interference in genetic mapping?
A. An event that increases crossover events
B. The suppression of additional crossovers near an initial crossover
C. Random assortment of genes
D. Crossing over in non-linked genes
Answer: B
23. Which of the following describes a linkage map?
A. Based on physical DNA sequences
B. Based on gene interactions
C. Based on recombination frequencies
D. Based on chromosome number
Answer: C
24. The presence of fewer recombinant offspring than expected indicates:
A. No genetic linkage
B. Complete linkage
C. Partial linkage
D. Random assortment
Answer: C
25. Crossovers most commonly occur during:
A. Prophase of mitosis
B. Prophase I of meiosis
C. Metaphase of mitosis
D. Anaphase II of meiosis
Answer: B
26. A recombination frequency of less than 50% suggests:
A. Independent assortment
B. Partial linkage
C. Complete dominance
D. Multiple alleles
Answer: B
27. In a dihybrid test cross, recombinant offspring represent:
A. The parental genotype
B. The outcome of crossing over
C. The absence of linkage
D. Dominant phenotypes only
Answer: B
28. What is the relationship between map distance and recombination frequency?
A. Directly proportional
B. Inversely proportional
C. Unrelated
D. Non-linear
Answer: A
29. Chromosomal interference is measured by:
A. The frequency of double crossovers
B. The ratio of recombinants to parentals
C. The observed vs. expected double crossover ratio
D. The distance between two genes
Answer: C
30. Genes showing linkage disequilibrium are:
A. Randomly inherited
B. Inherited together more often than expected
C. Located on different chromosomes
D. Mutated genes
Answer: B
