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AP®Environmental ScienceCollege BoardExam QuestionsUnit 3: PopulationsK-Selected & r-Selected Species

K-Selected & r-Selected Species (College Board AP® Environmental Science): Exam Questions

7 mins7 questions
11 mark

Which of the following describes a K-selected species?

  • Produces a large number of offspring with minimal parental care.

  • Exhibits rapid growth and early reproduction.

  • Invests significant parental care in a few offspring, leading to higher survival rates.

  • Thrives in unpredictable environments with frequent disturbances.

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21 mark

Which of the following best explains why K-selected species are more adversely affected by invasive species than r-selected species? 

  • K-selected species have higher reproductive rates than r-selected species, allowing them to quickly adapt to new competitors.

  • K-selected species have a lower reproductive rate than r-selected species, making them more vulnerable to rapid changes in their environment.

  • K-selected species have shorter lifespans than r-selected species, allowing them to recover quickly from disturbances.

  • K-selected species are typically generalists, enabling them to outcompete invasive species.

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31 mark

Which of the following is the correct method to calculate the population growth rate (r)?

  • r space equals space fraction numerator b i r t h s space plus space d e a t h s space plus space i m m i g r a t i o n space plus space e m i g r a t i o n over denominator i n i t i a l space p o p u l a t i o n end fraction

  • r space equals space fraction numerator b i r t h s space plus space i m m i g r a t i o n space minus space d e a t h s space plus space e m i g r a t i o n over denominator i n i t i a l space p o p u l a t i o n end fraction

  • r space equals space fraction numerator b i r t h s space minus space d e a t h s space x space i m m i g r a t i o n space x space e m i g r a t i o n over denominator i n i t i a l space p o p u l a t i o n end fraction

  • r space equals space fraction numerator b i r t h s space x space space d e a t h s space plus space i m m i g r a t i o n space minus space e m i g r a t i o n space over denominator i n i t i a l space p o p u l a t i o n end fraction

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41 mark

A population of rabbits starts with 200 individuals. Over the course of a year, 50 rabbits are born, 20 die, 10 immigrate, and 5 emigrate. What is the population growth rate (r)?

  • 0.175 (17.5%)

  • 0.125 (12.5%)

  • 0.075 (7.5%)

  • 0.225 (22.5%)

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51 mark

Which of the following describes a strategy used by K-selected species to ensure maximum survival of offspring?

  • Producing a large number of offspring with little parental care.

  • Reaching reproductive maturity quickly and reproducing frequently.

  • Having short lifespans and high juvenile mortality rates.

  • Providing extensive parental care and investing significant resources in a few offspring.

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61 mark

Which curve most likely represents an r-selected species that has just colonized a new environment?

Four graphs labelled A to D. Graph A shows population peaking and declining. B shows exponential growth. C shows logistic growth. D shows fluctuations around carrying capacity.

  • A

  • B

  • C

  • D

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71 mark

Which curve most likely represents a K-selected species that is well established in an area? 

Four graphs labelled A to D show population size over time: A peaks and declines, B grows exponentially, C stabilises after growth, D fluctuates after growth.

  • A

  • B

  • C

  • D

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