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Chapter 5 Section 1 How Populations Grow. Objectives: -List the characteristics used to describe a population -Identify factors that affect population size -Differentiate between exponential and logistic growth
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Chapter 5 Section 1How Populations Grow Objectives: -List the characteristics used to describe a population -Identify factors that affect population size -Differentiate between exponential and logistic growth AZ Science Standard: Assess how the size of and the rate of growth of a population are determined by birth and death rate, immigration, emigration, and carrying capacity of the environment.
Characteristics used to describe populations: Geographic Distribution: Population Density: Number of individuals per unit area Population density = Number of individuals Unit area • The area inhabited by a population • Described as Squared km
Population Density Continued • Suppose there are 150 bullfrogs living in a pond that covers an area of 3 square kilometers. What is the density of the bullfrog population? • Pop. Density = 150 bullfrogs = 50 bullfrogs/km2 3 km2
Population Growth: • Factors that affect population size: • Number of births • Number of deaths • Number of individuals that enter or leave the population (immigration and emigration)
Population Growth: • Immigration – the movement of individuals into an area • Emigration – the movement of individuals out of an area
Population Growth Exponential Growth: Under ideal conditions with unlimited resources, a population will grow exponentially J-Shape curve • Growth pattern in which the individuals in a population reproduce at a constant rate
Population Growth Logistic Growth: S-shape curve • Growth pattern in which a population’s growth rate slows or stops following a period of exponential growth
Logistic Growth (S-shaped curve) • Carrying Capacity- largest number of individuals of a population that a given environment can support • Determined by: Food, nutrients, space, water, etc.
Carrying capacity # Number of Yeast cells Time (hours)