SAT Subject Biology Practice Question 214: Answer and Explanation
4. Which of the following characteristics of an allele is required for it to increase in a population through natural selection?
A. Individuals with the allele are better able to find food.
B. Individuals with the allele are better able to resist disease.
C. Individuals with the allele have an increased ability to find and retain mates.
D. Individuals with the allele produce more offspring that reach adulthood.
E. Individuals with the allele have a longer lifespan than those without it.
Correct Answer: D
In order for an allele to be acted on by natural selection, it must result in an increase in fitness. Fitness is defined as the ability to pass traits on to offspring. Therefore, individuals that produce the greatest number of offspring that grow to become fertile adults have the greatest fitness.