Question

consider the following scenarios:

1. in mosquitoes, whether their bites can be felt by humans is a genetic trait of the mosquito. over time, humans who feel mosquitoes biting swat and kill so many mosquitoes that most of the remaining mosquitoes possess bites that cannot be felt.
2. orchid collectors search the rainforest for rare orchids. some orchids have alleles that allow their roots to adhere to trees so strongly that they cannot be removed without killing the plant. the collectors leave these individuals alone and collect the others. after a while, most orchids remaining in the forest display the strong adherence trait.
3. a person is given a medication to alleviate back pain. after a few months, the person must increase the dosage because the initial dose no longer has the same effect.
4. your neighbor treats his yard with a brand new herbicide to control weeds. none of the weeds are killed by the herbicide.

which scenarios provide examples of evolution?
correct answer(s)
scenario 1, scenario 2, scenario 3, scenario 4 (each in a yellow box)

Explanation:

• Scenario 1: Mosquitoes with unfelt - bite trait survive (natural selection), changing population genetics over time (evolution).
• Scenario 2: Orchids with strong - adherence trait survive (selection by collectors), altering population traits (evolution).
• Scenario 3: This is drug tolerance (individual physiological change, not population - level genetic change, so not evolution).
• Scenario 4: If no weeds are killed, there's no selection (no change in weed population genetics, so not evolution).

Answer:

scenario 1, scenario 2