AK SCI Review - Life Sci 3

Analyze the data: In a forest ecosystem, the population of deer has decreased significantly. What could be a possible reason for this change?

• Increase in the number of predators

• Abundance of food resources

• Decrease in predator population

• Stable climate conditions

Answer explanation

The significant decrease in the deer population is likely due to an increase in the number of predators, which can lead to higher predation rates and reduced deer survival.

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Which of the following interactions is an example of mutualism in an ecosystem?

• A lion hunting a zebra

• Bees pollinating flowers

• A bird eating a worm

• A cat chasing a mouse

Answer explanation

Bees pollinating flowers is mutualism because both species benefit: bees get nectar for food, while flowers receive help with reproduction through pollination.

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What is the primary source of energy for most ecosystems on Earth?

• Wind

• Water

• Sunlight

• Geothermal heat

Answer explanation

The primary source of energy for most ecosystems on Earth is sunlight. It drives photosynthesis in plants, which forms the base of the food chain, supporting all other life forms.

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How might the introduction of a new predator affect the population of prey in an ecosystem?

• Increase the prey population

• Decrease the prey population

• Have no effect on the prey population

• Cause the prey to become predators

Answer explanation

The introduction of a new predator typically leads to increased predation on the prey species, resulting in a decrease in their population. This dynamic is a fundamental aspect of predator-prey relationships in ecosystems.

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Which of the following is a strategy to maintain biodiversity in an ecosystem?

• Deforestation

• Pollution

• Establishing protected areas

• Overfishing

Answer explanation

Establishing protected areas is a key strategy to maintain biodiversity, as it safeguards habitats and species from threats like deforestation, pollution, and overfishing, promoting ecosystem health and resilience.

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In a desert ecosystem, what effect does limited water availability have on the organisms living there?

• Increases population growth

• Decreases competition for resources

• Limits population size

• Promotes unlimited growth

Answer explanation

Limited water availability in a desert ecosystem restricts the resources necessary for survival, leading to lower population sizes. Organisms must compete for scarce water, which ultimately limits their growth and reproduction.

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Which of the following is an example of a parasitic relationship?

• A bee collecting nectar from a flower

• A tapeworm living in the intestines of a mammal

• A bird building a nest in a tree

• A fish swimming in a school

Answer explanation

A tapeworm living in the intestines of a mammal is a clear example of a parasitic relationship, where the tapeworm benefits at the expense of the host, causing harm to the mammal.

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What role do decomposers play in the cycling of matter in an ecosystem?

• They produce energy from sunlight

• They break down dead organisms and recycle nutrients

• They compete with producers for resources

• They consume primary consumers

Answer explanation

Decomposers play a crucial role in ecosystems by breaking down dead organisms, which recycles nutrients back into the soil. This process supports plant growth and maintains the balance of the ecosystem, making the correct choice essential.

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How can deforestation impact the populations of organisms in an ecosystem?

• Increase biodiversity

• Decrease available habitats

• Stabilize the ecosystem

• Increase food resources

Answer explanation

Deforestation leads to a loss of trees and vegetation, which decreases available habitats for many organisms. This loss can result in reduced populations and biodiversity, as species struggle to survive without their natural environments.

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Which of the following is a method to evaluate competing design solutions for maintaining ecosystem services?

• Ignoring environmental impact

• Considering economic, social, and environmental factors

• Focusing only on short-term benefits

• Prioritizing human needs over all else

Answer explanation

The correct choice, 'Considering economic, social, and environmental factors', emphasizes a holistic approach to evaluate design solutions, ensuring that ecosystem services are maintained while balancing various impacts.

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