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What Is a Genetic Mutation?

Science · Ecosystems & Habitats · ages 12-14

Name ______________________ Date ____________

Which option is a mutagen that can increase the chance of DNA mutations?
- Ordinary sound from a nearby radio
- Gentle pressure from a loose shirt
- Ultraviolet radiation from the sun
What is a genetic mutation?
- A lasting change in DNA position
- A lasting change in DNA sequence
- A lasting change in DNA activity
Every mutation harms the organism that carries it.
Circle one: True False
UV damages a skin cell's DNA. Repair restores the original letter sequence before any lasting change remains. What can you conclude?
- Repair never changes damaged DNA.
- The repaired site passes a changed sequence to all children.
- Damage occurred, but no mutation remains at that site.
A cell copies the DNA section CGAT as CGGT. The change remains uncorrected. What caused this mutation?
- An uncorrected error during DNA copying
- DNA damage following exposure to ultraviolet radiation
- A useful change directly produced by natural selection
Which process creates a new gene version, rather than mixing or spreading existing versions?
- Mutation changes DNA to create a new version.
- Natural selection creates a new gene version.
- Perfect copying changes DNA to create a new version.
Lina says beetles produce a darker-shell mutation because they need camouflage. Which statement corrects this idea?
- Mutations arise without regard to whether beetles need them.
- Beetles make any DNA change they need.
- Mutations can arise only when beetles need a new useful trait.
An inherited mutation helps beetles leave more surviving offspring. A student says it must disappear after one generation. Which statement corrects the claim?
- It must vanish from the population after one generation.
- It may become more common in the population over generations.
- It must reach every beetle in the population in one generation.

Answer key

For grown-ups. Fold this page away before handing over the rest.

What Is a Genetic Mutation? W1-mt_rOqo-8GeKt-s1

Ultraviolet radiation from the sun · UV radiation is a mutagen. It can damage DNA and increase the chance of mutations, although cells can repair some damage.
A lasting change in DNA sequence · A mutation changes DNA's sequence. Moving chromosomes or using unchanged DNA instructions does not by itself change that sequence.
False · Mutations can be neutral, harmful or beneficial. A neutral mutation has no effect on survival or reproduction, so not every mutation causes harm.
Damage occurred, but no mutation remains at that site. · Damage and mutation are different. Here, repair restored the original sequence, so the damaged site has no lasting mutation.
An uncorrected error during DNA copying · The prompt identifies an uncorrected copying error. The third letter changed from A to G during copying; no UV exposure is described.
Mutation changes DNA to create a new version. · Mutation changes DNA and creates new gene versions. Perfect copying preserves a version. Natural selection can change how common an inherited version becomes.
Mutations arise without regard to whether beetles need them. · A need for camouflage does not direct a useful DNA change. A mutation may arise first; whether it helps depends on its effects and the environment.
It may become more common in the population over generations. · Offspring can inherit this mutation. If carriers leave more surviving offspring, natural selection can make it more common, though spread is not guaranteed.