This set of Cytogenetics Multiple Choice Questions on “DNA Mutation – 1”.
1. All mutations result in the production of a mutant.
A. True
B. False
Answer: B
Clarification: Any change in genetic constitution of the organism is termed as mutation, but only when the phenotypic expression is changed it is called a mutant.
2. Which of the following is not a point mutation?
A. Substitution
B. Transposition
C. Insertion
D. Transversion
Answer: B
Clarification: Point mutation concerns a single base. Thus substitution, which includes transversion, and insertion or deletion, falls within point mutation. On the other hand, translocation involves a stretch of bases so it is not a point mutation.
3. ‘Delicious apples’ can’t be propagated through_____________
A. Stem
B. Leaf
C. Seed
D. Tissue culture
Answer: C
Clarification: Delicious apple was produced first as a somatic mutation within a branch and was since propagated vegetatively. As somatic mutations don’t affect germ cells, it can’t be propagated through seeds.
4. Which of the following harmful mutations will have the most severe effect in the progeny?
A. Mutation in a muscle tissue
B. Mutation in a gamete
C. Mutation in sperm mother cells
D. Mutation in mammary gland tissue
Answer: C
Clarification: Option a and d are somatic tissue, their mutation will not be propagated. A single gamete will only have a slight chance to fertilize and lead to mutation, but sperm mother mutation will produce many lethal gametes that will increase the probability.
5. The number of times a particular mutation occurs in a population of cells or individuals is known as __________
A. Mutation rate
B. Mutation frequency
C. Mutation count
D. Mutation efficiency
Answer: B
Clarification: While mutation frequency is the number of times a particular mutation occurs in a population, mutation rate is the probability of a particular type of mutation per unit time.
6. Total number of transition and transversion that can take place in genome is___________
A. 2 and 6
B. 6 and 4
C. 4 and 6
D. 4 and 8
Answer: D
Clarification: Transition is the replacement of a purine by another purine or a pyrimidine by another pyrimidine. Transversion is the replacement of a purine by a pyrimidine, or a pyrimidine by a purine. So there are 4 possible transition A—G and C— T, and 8 possible transversions A—C, A—T, G—C, G—T.
7. Sickle cell anemia is a result of _______________
A. Non sense mutation
B. Mis-sense mutation
C. Sense mutation
D. Frame shift mutation
Answer: B
Clarification: In this disease, a GAG is converted to a GUG, i.e a glutamic acid is converted to a valine. This is example of a mis-sense mutation where a change of base codes for a different amino acid from the original.
8. A frame shift mutation will have minimum effect when it leads to ______________
A. Insertion of 2 bases
B. Deletion of 1 base
C. Insertion of 3 bases
D. Deletion of 2 bases
Answer: C
Clarification: Frame shift mutations lead to lease effect when they lead to an insertion or deletion of 3 bases, as due to our codon being triplet this doesn’t shift the reading frame. However, if the codon thus lost or added is a very important one in the gene, there could be serious consequences.
9. Wooble base recognition of the tRNAs in translation ignores which of the mutation?
A. Frame shift
B. Neutral
C. Silent
D. Sense