Population Dynamics

What happens during logistic growth?

• The population growth rate slows or stops after a period of exponential growth

• The population remains constant

• The population grows exponentially without stopping

• The population decreases rapidly

Answer explanation

During logistic growth, the population initially grows exponentially but then the growth rate slows or stops as it approaches the carrying capacity of the environment, making this the correct choice.

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What is carrying capacity?

• The number of organisms that can migrate to an area

• The number of predators an area can support

• The number of organisms of one species that can be supported in an environment

• The maximum number of different species in an area

Answer explanation

Carrying capacity refers to the maximum number of organisms of one species that an environment can support sustainably, considering resources and space. This distinguishes it from other options that focus on migration or species diversity.

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Which of the following is a density-dependent factor?

• Unusual weather

• Volcanic eruptions

• Floods

• Competition

Answer explanation

Competition is a density-dependent factor because it affects population growth based on the population size. As the population increases, competition for resources like food and space intensifies, impacting survival and reproduction.

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Which of the following is a density-independent factor?

• Disease

• Parasitism

• Fires

• Predation

Answer explanation

Fires are a density-independent factor because they affect populations regardless of their density. In contrast, disease, parasitism, and predation are density-dependent factors, as their impact varies with population size.

What is an example of a density-dependent factor affecting bears?

• Floods reducing food supply

• Competition for food among bears

• Unusual weather patterns

• Volcanic eruptions

Answer explanation

Competition for food among bears is a density-dependent factor because it directly relates to the population size. As bear populations increase, competition for limited food resources intensifies, impacting their survival and reproduction.

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How do ecologists estimate the size of a large population?

• By observing their behavior

• By measuring the area they occupy

• By using a sampling method

• By counting every individual

Answer explanation

Ecologists estimate large population sizes effectively by using a sampling method. This approach allows them to gather data from a smaller, manageable portion of the population and extrapolate the total size, rather than counting every individual.

What can cause a population to grow exponentially?

• Frequent natural disasters

• Abundant space and food, and protection from predators and disease

• Increased predation

• Limited space and food

Answer explanation

A population can grow exponentially when there is abundant space and food, along with protection from predators and disease. These conditions allow for higher survival and reproduction rates, leading to rapid population increase.

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What is a consequence of competition in a population?

• Increase in population size

• Decrease in population size

• Stable population size

• Unchanged population dynamics

Answer explanation

Competition in a population often leads to limited resources, which can result in a decrease in population size as individuals struggle to survive and reproduce.

What is the effect of predation on prey populations?

• Has no effect on prey population

• Decreases prey population

• Increases prey population

• Stabilizes prey population

Answer explanation

Predation directly impacts prey populations by reducing their numbers. Predators hunt and consume prey, leading to a decrease in their population size, which is why the correct answer is 'Decreases prey population'.

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Which of the following is NOT a density-dependent factor?

• Parasitism

• Floods

• Disease

• Competition

Answer explanation

Floods are abiotic factors and affect populations regardless of their density, making them density-independent. In contrast, parasitism, disease, and competition are influenced by population density, thus are density-dependent factors.

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