Life Sciences Multiple Choice Questions on “Genetic Linkage”.
1. The tendency of two or more than two genes to stay together during inheritance is called ___________
A. Genetics
B. Gene interaction
C. Crossing over
D. Linkage
Answer: D
Clarification: Linkage is the tendency of two or more than two genes to stay together during the inheritance. It exists in two forms i.e. cis and trans.
2. Which of the following statement is NOT true regarding linkage group?
A. Group of physically linked genes
B. Represent a haploid number of chromosomes
C. Shown by linkage map
D. Linkage groups are not correlated with each other
Answer: D
Clarification: The linkage group refers to the group of genes physically linked together. The number of linkage group represents the haploid number of chromosomes in a species, i.e. the number of linkage group can be correlated as the number of homologous pairs.
3. The linkage maps are constructed by using recombination frequencies between genes.
A. True
B. False
Answer: A
Clarification: The linkage map is the representation of all the genes of a linkage group on a single line in the same order in which they are present on the chromosome.
4. What is the unit of linkage map?
A. Morgan
B. Centi-morgan
C. Centimeter
D. Angstrom
Answer: B
Clarification: The linkage maps are constructed by using recombination frequencies between genes which is determined by the test cross. The distance is measured from centi-morgan (cM), it represents the unit of the map.
5. What is the maximum percentage of recombination frequency between two genes?
A. 75%
B. 100%
C. 50%
D. 25%
Answer: B
Clarification: Recombination frequency is the measure of genetic linkage; it should not exceed 50%. The maximum limit of recombination is 50%.
6. Name the phenomenon which can break the occurrence of linkage?
A. Crossing over
B. Linkage
C. Reconstruction
D. Breakage
Answer: A
Clarification: Linkage can be broken by the process of homologous recombination (crossing over) which occurs at the pachytene stage of prophase I.
7. Failure in which of the following phenomenon would result in linkage?
A. Law of dominance
B. Law of segregation
C. Law of independent assortment
D. Law of separation
Answer: C
Clarification: Alignment of chromosomes in metaphase one will give two gametes, but a failure of independent assortment would result in the linkage of genes on the chromosomes.
8. Name the organism whose first genetic map was made?
A. Rat
B. Arabidopsis
C. Fly
D. Drosophila
Answer: D
Clarification: T.H. Morgan first studied linkage in Drosophila malanogester in which genes on a chromosome are linked (systemic gene).
9. Two genes are 70cM apart, calculate the recombination frequency?
A. 50%
B. 100%
C. 25%
D. 23%
Answer: A
Clarification: Recombination frequency is the measure of genetic linkage. Recombination frequency should not exceed 50%. The maximum limit of recombination is 50%.
10. Name the sites of DNA, which have a high probability of crossing over?
A. Cold spots
B. Hot spots
C. Covalent bond
D. Hydrophobic bond
Answer: B
Clarification: There are certain sites on DNA, which have a high probability of crossing over called hot spots and those sites which have a low probability of crossing over are called cold spots.
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