Population Dynamics: Sec. 1: Characteristics of Populations

What is a population in ecological terms?

• A group of different species living in the same area

• A group of organisms of different species living in different areas

• A group of organisms of the same species living in the same area

• A single organism living in an area

Answer explanation

In ecological terms, a population refers to a group of organisms of the same species living in the same area. This distinguishes it from other options that involve different species or individual organisms.

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What is population density?

• The number of species in an area

• The number of individuals per unit area

• The number of organisms in a sample

• The number of predators in an area

Answer explanation

Population density refers to the number of individuals per unit area, making it a measure of how crowded a particular area is with individuals of a species. This distinguishes it from other options that focus on species or predators.

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What is exponential growth?

• When a population grows at a constant rate

• When a population grows and then decreases

• When a population decreases at a constant rate

• When a population remains the same size

Answer explanation

Exponential growth occurs when a population increases at a constant rate, meaning it grows faster as the population size increases. This is different from the other options, which describe different growth patterns.

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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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NGSS.MS-LS2-4

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 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.

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.

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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