Question

Examine the two strands of DNA below. Which kind of mutation occurred?

Original strand: AGC GTA CCC TAC

New strand: AGC GTA ACC TAC

(1 point)
Responses

substitution
substitution

deletion
deletion

insertion
insertion

frameshift

Answer 1

Millions of years ago, the ancestors of giraffes had short necks and used to eat leaves from the bushes on the ground. A genetic mutation caused one giraffe's neck to be taller. This long-necked giraffe was able to eat leaves that were higher up on trees. This gave it an advantage as it was able to access more food than other giraffes. Over millions of years, all of the giraffes became long-necked. Which type of environmental factor caused this mutation to be inherited? (1 point)
Responses

radiation exposure
radiation exposure

food availability
food availability

polluted environment
polluted environment

exercise requirement

Answer 2

What is one way that a frameshift mutation could occur? (1 point)
Responses

two nucleotides are deleted
two nucleotides are deleted

three nucleotides are inserted
three nucleotides are inserted

two nucleotides are substituted
two nucleotides are substituted

three nucleotides are deleted

Answer 3

The change from the original strand "AGC GTA CCC TAC" to the new strand "AGC GTA ACC TAC" indicates that one nucleotide has been altered. Specifically, the third codon changed from "CCC" to "ACC", which represents a single base change (C to A).

This type of mutation is characterized as a **substitution** mutation.

Therefore, the answer is **substitution**.

Answer 4

The type of environmental factor that influenced the inheritance of the long neck mutation in giraffes is **food availability**. The taller neck allowed giraffes to access food that was not available to their shorter-necked ancestors, giving them a survival advantage and leading to the eventual prevalence of the trait in the population.

Therefore, the correct response is **food availability**.

Answer 5

A frameshift mutation occurs when nucleotides are inserted or deleted from the DNA sequence in a number that is not a multiple of three. This shifts the reading frame of the codons during translation, potentially altering all subsequent amino acids.

Among the options provided, **two nucleotides are deleted** would cause a frameshift mutation because it changes the overall grouping of the codons (not a multiple of three).

Thus, the correct answer is **two nucleotides are deleted**.