An exchange of chromosome parts between chromosomes from different pairs
Explication
A translocation is an exchange of chromosome segments between chromosomes from different pairs. It is a structural chromosome mutation, not a point mutation.
Substitution
Explication
A substitution is a point mutation in which one nitrogenous base is replaced by another. Insertions add a nucleotide, and deletions remove one.
Inversion
Explication
An inversion is a rearrangement in which a chromosome segment is reversed in orientation. Unlike deletion, the segment is not lost, just rearranged.
Only one chromosome is present instead of two for a given pair
Explication
Monosomy is the condition in which one chromosome is present instead of the usual two for a pair. An extra chromosome would be trisomy, not monosomy.
Because DNA repair mechanisms correct them before division
Explication
DNA repair mechanisms fix many DNA changes before they can be transmitted to daughter cells. The other choices confuse repair with transcription, gamete formation, or chromosome-level mutations.
A chromosome pair with an abnormal number of copies
Explication
Aneuploidy means a chromosome pair does not have the normal number of copies. Polyploidy is different because it involves extra complete sets of chromosomes.
Transcription occurs in the nucleus and translation in the cytoplasm
Explication
In eukaryotes, transcription takes place in the nucleus and translation occurs in the cytoplasm. This separation is a key feature of protein synthesis in these cells.
By causing individuals with different genome duplications to become reproductively isolated
Explication
Polyploidization can lead to reproductive isolation when individuals with different chromosome-set numbers can no longer interbreed successfully. That isolation can eventually produce a new species.
Having more than two complete sets of chromosomes
Explication
Polyploidy means an organism carries more than two complete chromosome sets. The other options describe aneuploidy, inversion, or a point mutation.
Because of redundancy in the genetic code
Explication
The genetic code is redundant, so different codons can specify the same amino acid, producing a silent mutation. The other options contradict how codons and translation work.
The production of messenger RNA from a gene using DNA information
Explication
Transcription is the synthesis of mRNA from a gene using DNA as the template. Translation, not transcription, is the step that produces protein.
A mutation in a germline cell
Explication
Only mutations in germline cells can enter gametes and be inherited by the next generation, so they can affect evolution. Somatic-cell mutations stay in the individual and are not transmitted.
They create heritable variation in DNA sequences
Explication
Mutations change DNA sequences, and when those changes are inherited they generate genetic variation over time. DNA repair can correct many changes, but it does not create diversity.
They generate allelic diversity within populations
Explication
Mutations create new alleles, increasing genetic variation in populations and making evolutionary change possible. The other choices contradict the role of inherited variation.
Mémorisez les réponses avec 14 flashcards sur Genetic Mutations and Evolution.
Mutations — definition?
Changes in DNA passed to daughter cells.
Genetic diversity — source?
Mutations create inherited variation.
DNA repair — role?
Corrects mutations, preventing transmission.
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