Mutations Quiz
Questions: 16 · 10 minutes
1. What is a major function of DNA proofreading and repair systems?
To create variation by deliberately changing every copied gene
To ensure that all mutations are beneficial
To detect and correct many copying errors or damaged DNA sites
To translate altered genes into proteins before cell division
2. A population is kept away from known radiation and chemical mutagens, yet new mutations still appear. Which explanation is most accurate?
Mutations occur only when organisms need a new trait
Replication errors and spontaneous chemical changes can occur without external mutagens
Normal metabolism prevents spontaneous DNA changes
Every new mutation must have been inherited unchanged from an ancestor
3. Two different missense mutations each replace one amino acid in the same protein. Which conclusion is most accurate?
Both must prevent the protein from being produced
They must affect the protein in exactly the same way
Their effects can differ depending on the amino acid change and its location
Neither can affect protein function because the reading frame remains unchanged
4. A DNA sequence changes from ACGT to ATGT, with no nucleotides added or removed. What type of mutation occurred?
Insertion
Translocation
Duplication
Substitution
5. Which statement best describes the possible effects of mutations?
Mutations are harmful only when they occur in reproductive cells
Mutations always improve an organism's adaptation
Mutations never affect traits unless an entire chromosome is lost
Mutations may be harmful, neutral, or beneficial depending on context
6. A person has one typical allele and one recessive disease-associated allele for a gene. What is generally possible?
The recessive allele must be removed during cell division
Every child will inherit the recessive allele and show the condition
The person may not show the recessive condition but can pass the allele to offspring
The typical allele will permanently rewrite the recessive allele
7. Exactly three nucleotides are deleted from the middle of a protein-coding sequence. Assuming they correspond to one complete codon, what is the likely result?
Every downstream codon shifts into a new reading frame
The whole gene is transferred to a different chromosome
One amino acid is removed without necessarily shifting the downstream reading frame
A premature stop codon must appear at the deletion site
8. Ultraviolet radiation damages DNA in a skin cell. Which statement best explains how this exposure could lead to a mutation?
Incorrect bases may be incorporated if the damage is copied or repaired inaccurately
The radiation directly replaces every damaged gene with RNA
The exposure converts the skin cell into a reproductive cell
Every damaged DNA molecule permanently loses an entire chromosome
9. A mutation occurs in a gene's regulatory region rather than in its protein-coding sequence. What could it directly change?
The chromosome number in every cell
The amino acid meanings assigned to all codons
The identity of every protein made by the cell
When, where, or how much the gene is expressed
10. Which statement best defines a genetic mutation?
The routine copying of DNA before a cell divides
A change in the nucleotide sequence of genetic material
The use of an RNA template to build a protein
The separation of homologous chromosomes during meiosis
11. A segment breaks from one chromosome and attaches to a different, nonhomologous chromosome. What kind of chromosome mutation is this?
Inversion
Translocation
Frameshift
Point substitution
12. A codon changes, but it still specifies the same amino acid. How is this mutation classified?
Missense mutation
Nonsense mutation
Frameshift mutation
Silent mutation
13. Which change is characteristic of a nonsense mutation?
A codon for an amino acid becomes a premature stop codon
A codon changes without altering its amino acid
One amino acid is replaced by another
A chromosome segment reverses its orientation
14. A mutation occurs in a cell that will produce an egg. Why can this mutation matter to the next generation?
It may enter the fertilized egg and be inherited by offspring
It must spread to every body cell before fertilization
It will always cause the offspring to show a new trait
It can be inherited only if the same mutation occurs in the other parent
15. A mutation allows some bacteria to survive an antibiotic that kills other bacteria. In that environment, how is the mutation best described?
Beneficial to the bacteria carrying it because it improves survival under antibiotic exposure
Neutral because mutations cannot influence reproductive success
Harmful because every DNA change reduces fitness
Silent because the bacteria remain the same species
16. One nucleotide is inserted near the beginning of a protein-coding sequence. What is the most likely immediate consequence?
The entire chromosome is copied
The reading frame shifts for downstream codons
Only the inserted nucleotide is translated differently
The gene automatically moves to another chromosome