Question

which statement best describes natural selection?
only the largest and strongest survive
the best adapted (most fit) individuals survive and reproduce, which passes their genes onto the next generation
random assortment of genes results in better characteristics in the following generations
some live and some die in each generation
in northern canada, a population of rabbits was predominantly white in color. the allele for white color is recessive, while the allele for gray color is dominant. over the last several decades, the average annual temperature of this area has increased, and the long - term deposits of ice and snow have become scarce. we see the result of this change in the graph below.
change in rabbit population 1850 - 2000
how can we explain this change in terms of allelic frequency?
changes in the environment caused genetic mutations that were passed to offspring.
in order to survive, rabbits changed from white to gray and they passed the gray allele to offspring.
gray alleles are dominant over white.
gray rabbits were more likely to survive in the changed habitat. the gray alleles were passed to offspring.

Explanation:

• For the first question:
• Natural selection is about the survival and reproduction of the fittest. It's not just about size and strength (so "Only the largest and strongest survive" is wrong). Random assortment of genes is more related to meiosis and genetic variation in a different context (not natural selection as described here). "Some live and some die in each generation" is too vague. The best - adapted individuals passing on their genes is the core of natural selection.
• For the second question:
• Genetic mutations are random and not directly caused by environmental changes in the way described in the first option. Organisms don't "decide" to change their traits for survival (second option is wrong). While gray alleles being dominant is a fact about genetics, it doesn't explain the change in allelic frequency in the context of the environment. The key is that gray rabbits were better adapted (more likely to survive) in the changed (less snowy) habitat, and thus their alleles (gray) were passed on more frequently.

Answer:

1. B. The best adapted (most fit) individuals survive and reproduce, which passes their genes onto the next generation
2. D. Gray rabbits were more likely to survive in the changed habitat. The gray alleles were passed to offspring.