IGCSE Biology 12 Views 1 Answers
Interpret graphs and diagrams of population growth
Interpret graphs and diagrams of population growth
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Interpreting graphs and diagrams of population growth involves understanding the different growth patterns exhibited by populations under varying environmental conditions. The two primary types of population growth graphs are exponential growth and logistic growth. Each type has distinct characteristics and implications for how populations behave over time.
1. Exponential Growth Graph
- Shape: This graph is typically J-shaped.
- Description: Exponential growth occurs when a population increases at a constant rate, leading to rapid growth over time, especially when resources are unlimited.
- Characteristics:
- The growth rate remains constant regardless of population size.
- As the population grows, the number of new individuals added increases, resulting in a steep upward curve.
- This pattern is often observed in ideal conditions, such as in newly colonized habitats or in populations with abundant resources.
2. Logistic Growth Graph
- Shape: This graph is S-shaped (sigmoid).
- Description: Logistic growth reflects a more realistic scenario where population growth is limited by resource availability and environmental factors.
- Characteristics:
- The graph begins with a lag phase where growth is slow as individuals acclimate to their environment.
- Following the lag phase, there is an exponential phase where the population grows rapidly.
- As the population approaches the carrying capacity (the maximum sustainable population size), the growth rate slows down due to limited resources, leading to a stationary phase where births equal deaths.
- Eventually, if conditions worsen or resources become depleted, the population may enter a decline or death phase.
Phases of Logistic Growth
- Lag Phase: Initial slow growth as individuals adapt to the environment.
- Exponential Phase: Rapid increase in population size as resources are plentiful.
- Stationary Phase: Growth stabilizes as the population reaches carrying capacity; births equal deaths.
- Death Phase (if applicable): Population may decline due to resource depletion or other limiting factors.
Factors Influencing Population Growth
Population growth is influenced by several key factors:
- Food Supply: Availability of food directly impacts birth rates and survival.
- Competition: Increased competition for limited resources can slow growth rates.
- Predation: Higher predation rates can decrease population size and growth potential.
- Disease: Outbreaks can lead to increased mortality, affecting overall population dynamics.
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