Question

post test: the interdependence of ecosystems
an ecosystem is shown in the illustration. assume that human activities have led to a decrease in the number of eagles. a virus attack on rabbits has led to a decrease in their population in the ecosystem. which two sentences describe likely effects on the ecosystem?
theres an increase in the number of snakes and insects and a decrease in the number of frogs.
theres an increase in the number of snakes and insects, and the storks face increased competition for food.
theres an increase in the number of storks and a decrease in the number of snakes and insects.
theres an increase in the number of frogs and a decrease in the number of storks and insects.
theres a decrease in the number of snakes, insects, and frogs.

Explanation:

1. Eagle population decrease: Eagles prey on snakes, so fewer eagles mean less predation pressure on snakes, causing the snake population to increase.
2. Rabbit population decrease: Rabbits compete with insects for grass (their shared food source). Fewer rabbits mean more grass available for insects, so the insect population increases.
3. Increased snakes and insects: Snakes prey on frogs, so more snakes will lead to more frog predation, decreasing the frog population. Storks prey on frogs; with fewer frogs, storks will face increased competition for their limited food source.

Answer:

• There's an increase in the number of snakes and insects and a decrease in the number of frogs.
• There's an increase in the number of snakes and insects, and the storks face increased competition for food.