Populations flashcards

A population is a group of individuals of the same species living in the same area at the same time. Students must understand how populations grow, including exponential and logistic growth models, and what factors limit population size. Key concepts include carrying capacity, biotic potential, and the difference between density-dependent and density-independent limiting factors. Students should also know how to interpret and use population data, including age structure diagrams, survivorship curves, and calculations involving birth rate, death rate, immigration, and emigration. Understanding how human population growth differs from other species, and how resource availability shapes population dynamics, is essential. These ideas connect to broader themes like ecosystem stability, resource use, and sustainability.

1. Card 1

   What is a population in ecology?

   A population is a group of individuals of the same species living in the same geographic area at the same time.

2. Card 2

   What is carrying capacity?

   Carrying capacity (K) is the maximum population size an environment can sustain long-term given available resources like food, water, and space.

3. Card 3

   Describe exponential population growth.

   Exponential growth occurs when a population increases at a constant rate, producing a J-shaped curve. It happens when resources are unlimited and there are no limiting factors.

4. Card 4

   Describe logistic population growth.

   Logistic growth produces an S-shaped curve. Growth is rapid at first, then slows as the population approaches carrying capacity due to increasing resource competition.

5. Card 5

   What is the formula for population growth rate?

   Population growth rate = (Birth rate + Immigration) - (Death rate + Emigration). A positive result means the population is growing.

6. Card 6

   What are density-dependent limiting factors?

   Density-dependent factors are limits on population growth whose effect increases as population density rises, such as disease, predation, and competition for food.

7. Card 7

   What are density-independent limiting factors?

   Density-independent factors affect population size regardless of density, such as natural disasters, extreme temperatures, and floods.

8. Card 8

   What does an age structure diagram show?

   An age structure diagram shows the proportion of a population in each age group, helping predict future growth, stability, or decline of a population.

9. Card 9

   What does a bottom-heavy age structure pyramid indicate?

   A wide base indicates a large proportion of young individuals, suggesting rapid population growth in the future as those individuals reach reproductive age.

10. Card 10

    What are the three types of survivorship curves?

    Type I (late death, e.g. humans), Type II (constant death rate, e.g. birds), and Type III (early death, high offspring, e.g. fish and plants).

11. Card 11

    What is biotic potential?

    Biotic potential is the maximum reproductive rate of a population under ideal conditions with unlimited resources and no limiting factors.

12. Card 12

    What is a population crash and what can cause it?

    A population crash is a sudden sharp decline in numbers, often caused by overshooting carrying capacity, disease outbreak, or sudden loss of a key resource.

• Many students confuse carrying capacity with biotic potential, thinking carrying capacity is the fastest a population can grow rather than the maximum size the environment can support.
• Students often assume that a population stops growing completely once it reaches carrying capacity, when in reality it typically fluctuates around that value due to ongoing changes in resource availability.
• A common error is classifying a disease outbreak as density-independent because it seems like a natural event, when in fact disease spreads more easily at higher densities, making it a density-dependent factor.

Planning your revision? Read how to revise AP Environmental Science, or make cards from your own notes with the notes to flashcards tool.