PR Review

A population of frogs increased over 50 years. What best explains the increase in the size of the frog population?

• Fewer frogs were born than died.

• The frog population is always increasing because no animal eats panthers.

• More frogs were born than died.

• A lot of frogs were born and none of them died.

The tiger population has increased. What will likely happen to the worm population?

• increase. The larger tiger population will lead to fewer wild pigs. The smaller wild pig population will need fewer energy storage molecules to reproduce, so they will eat fewer worms. This will lead to more births than deaths in the worm population.

• increase. An increase in the size of any population leads to an increase in the sizes of all other populations in an ecosystem.

• stay the same. Tigers do not eat worms, so the number of births and deaths in the worm population will stay the same.

• decrease. The larger tiger population will leave fewer energy storage molecules available in the ecosystem for the worm population, so there will be fewer births in the worm population.

The grasshopper population decreased suddenly. What will likely happen to the size of the rat population as a result?

• stay the same. The size of their consumer population did not change, so the number of deaths in the rat population did not change. There will be the same number of births and deaths in the rat population.

• increase. The smaller grasshopper population will need fewer energy storage molecules so there will be more energy storage molecules available for the rat population to reproduce. This will lead to more births in the rat population.

• decrease. A decrease in any population leads to a decrease in the sizes of all other populations in the ecosystem.

• decrease. The smaller grasshopper population provides fewer energy storage molecules for the rat population, so the rat population will reproduce less. This will lead to fewer births than deaths in the rat population.

The sizes of the populations have been stable for the last 6 years, but recently the size of the wolf population increased. What will likely happen to the coyote population?

• decrease. Fewer energy storage molecules will be available to the coyote population from the smaller deer population, so the coyote population will reproduce less. This will lead to fewer births than deaths in the coyote population.

• decrease. The larger wolf population will leave fewer energy storage molecules for all other populations in the ecosystem, so the coyote population will reproduce less. This will lead to fewer births in the coyote population.

• increase. An increase in the size of any population leads to an increase in the sizes of all other populations in an ecosystem.

• stay the same. Coyotes and wolves do not eat each other, so the number of births and deaths in the coyote population will stay the same.

The data showed that all three populations were stable. Then the snail population increased suddenly. What will likely happen to the size of the perch population as a result?

• increase. An increase in any population within an ecosystem will lead to an increase in the sizes of all other populations in the ecosystem.

• increase. The larger snail population will provide more energy storage molecules for the perch population, so they will reproduce more. This will lead to more births than deaths in the perch population.

• stay the same. The size of its consumer population did not change, so the number of deaths in the perch population did not change. There will be the same number of births and deaths in the perch population.

• decrease. The larger snail population will take more energy storage molecules from the ecosystem, leaving fewer available for the perch population. This will lead to more deaths than births in the perch population.

he sizes of the populations have been stable for the last 10 years, but recently the size of the frog population decreased. What will likely happen to the spider population? The size of the spider population will . . .

• increase. The smaller frog population will leave more energy storage molecules for all other populations in the ecosystem, so all populations will reproduce more. This will lead to more births in the spider population.

• increase. More energy storage molecules will be available to the spider population from the larger fly population, so the spider population will reproduce more. This will lead to more births than deaths in the spider population.

• stay the same. Frogs and spiders do not eat each other, so the number of births and deaths in the spider population will stay the same.

• decrease. A decrease in the size of one population leads to a decrease in the sizes of all other populations in an ecosystem.