These feathers help the ducks stay warm in cold water. Ducks with thicker feathers are more likely to stay warm and survive in cold water. But, in warm water, thicker feathers can make the ducks overheat and die.
The diagram below shows a population of ducks that live in an area of an ocean. At time 1, the population had the same number of ducks with thin and thick feather layers. At time 2, after many generations, there were many more ducks with a thin feather layer and fewer ducks in the population with a thick feather layer.
2 diagrams, each containing rows of duck icons. The first diagram is titled Population at Time 1 and contains 2 rows of 4 duck icons each, one labeled Thin and one labeled Thick. The second diagram is titled Population at Time 2 and contains 2 rows of duck icons. The first row is labeled Thin and contains 8 duck icons. The second row is labeled Thick and contains 2 duck icons. An arrow points from the first diagram to the second diagram and is labeled: After Many Generations.
3. How did the environment change between time 1 and time 2? How did the population change?
Responses
a
The water became warm. As a result, ducks with thin feathers were more likely to survive, so the ducks with thick feathers changed to have thin feathers.
The water became warm. As a result, ducks with thin feathers were more likely to survive, so the ducks with thick feathers changed to have thin feathers.
b
The water became warm. As a result, ducks with thin feathers were more likely to survive, so both kinds of ducks passed on the gene for thin feathers to their offspring.
The water became warm. As a result, ducks with thin feathers were more likely to survive, so both kinds of ducks passed on the gene for thin feathers to their offspring.
c
The water became warm. With each generation, more ducks with thin feathers survived long enough to pass on the gene for thin feathers to their offspring.
The water became warm. With each generation, more ducks with thin feathers survived long enough to pass on the gene for thin feathers to their offspring.
d
You cannot tell how the environment changed. With each generation, more ducks passed on the gene for thin feathers to their offspring.
1 answer
The best response is:
c The water became warm. With each generation, more ducks with thin feathers survived long enough to pass on the gene for thin feathers to their offspring.
This response clearly explains the change in the environment (the warming of the water) and links it directly to the survival and reproductive success of ducks with thin feather layers over generations, which results in a population increase of those ducks.
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