If a population of short-lived, annually reproducing fish is exposed for several years in a row to a chemical toxin that kills 5% of them each year, what might you expect to happen if the population is re-exposed to the chemical several years later?
a. much higher death rate.
b. lower death rate.
c. about the same death rate.
d. no mortality—they will be immune to the toxin.
B
Fewer fish would die upon re-exposure. The population will have evolved resistance to the toxin. Natural selection (appearing in the form of the toxin) would have selected individuals that are naturally resistant to the toxin, allowing them to persist and reproduce, passing the resistant trait on within the next generation of fish.
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A synapse is
A) a close association between neurons. B) a neurotransmitter molecule. C) a type of protein. D) a gene that controls the nervous system.
Positive correlations have been found between ________
A) telomere lengths and longevity among individuals within populations B) telomere lengths and longevity across many species of mammals C) telomere lengths and longevity among individuals within populations and across many species of mammals D) neither telomere lengths and longevity among individuals within populations nor telomere lengths and longevity across many species of mammals
A tissue is generally composed of several organs.
a. true b. false
Imagine that smurfs live in widely separated groups and rarely interbreed, so geneticists know very little about them. On one occasion, two smurfs from different groups did mate. A big-footed, white smurf mated with a small-footed, blue smurf
Three offspring resulted: one big-footed and blue and two small-footed and blue. Which statement about the inheritance of color in smurfs is most likely to be correct? A) Blue is dominant to white. B) White and blue are codominant. C) White is dominant to blue.