Study Guide for Unit #3 Test (Ch 6 and 7)

Things to Know for Unit #3 Test (Ch 6 and 7)

1. Age Structures

  • Definition: Age structure refers to the distribution of various age groups in a population. This distribution is typically represented as a population pyramid.

  • Importance: Understanding age structures is crucial for predicting future population trends and assessing the potential for growth or decline.

2. Why Human Population Grew?

  • Historical Factors:

    • Improvements in healthcare, sanitation, and nutrition have significantly reduced mortality rates.

    • Agricultural advancements have increased food production, sustaining larger populations.

  • Modern Factors:

    • Population policies, immigration, and urbanization influence population dynamics today.

3. Demographic Transition

  • Definition: The demographic transition model illustrates the transition from high birth and death rates to low birth and death rates as a country develops.

  • Stages:

    1. Pre-Industrial Stage: High birth and death rates.

    2. Transitional Stage: Death rate declines due to improvements in healthcare; birth rate remains high.

    3. Industrial Stage: Birth rates begin to decline; population growth slows.

    4. Post-Industrial Stage: Both birth and death rates are low.

  • Implications: Impacts economic development, resource consumption, and environmental challenges.

4. Environmental Impact of Developing Countries

  • Key Concerns:

    • Rapid industrialization leads to increased pollution, deforestation, and habitat loss.

    • Resource depletion and waste generation increase due to population pressures.

  • Example: Countries like India and Indonesia face significant challenges in balancing development with sustainable practices.

5. Per Capita

  • Definition: Refers to an average per person measure, often used to evaluate economic performance or resource consumption (e.g., GDP per capita, emissions per capita).

  • Importance: Provides insight into living standards and environmental impact on a per-person basis.

6. K and r Selected Organisms

  • K-Selected Organisms:

    • Characteristics: Long lifespan, late maturity, low reproductive rates, high parental care.

    • Examples: Elephants, humans, and other large mammals.

  • r-Selected Organisms:

    • Characteristics: Short lifespan, early maturity, high reproductive rates, little parental care.

    • Examples: Bacteria, insects, and small rodents.

7. Survivorship Curves

  • Definition: Graphs that represent the number of individuals alive at each age for a species.

  • Types:

    • Type I: High survivorship in early/mid-life; most die at old age (e.g., humans).

    • Type II: Constant death rate throughout life (e.g., songbirds).

    • Type III: High mortality in early life; few survive to adulthood (e.g., fish).

8. Growth Rate (r)

  • Definition: The growth rate is the rate at which a population increases or decreases in size, calculated as the difference between birth rate and death rate.

  • Formula: r=b−dr = b - d
    where $b$ is the birth rate and $d$ is the death rate.

  • Significance: A critical factor in understanding population dynamics and future growth trends.

9. Doubling Time

  • Definition: The time it takes for a population to double in size at a constant growth rate.

  • Rule of 70: A quick way to estimate doubling time:

    • Formula: extDoublingTimeext(years)=rac70rext(asapercentage)ext{Doubling Time} ext{ (years)} = rac{70}{r ext{ (as a percentage)}}

  • Importance: Helps in planning for resource needs and potential environmental impacts.

10. Density Dependent vs. Density Independent Limiting Factors

  • Density-Dependent Factors:

    • Effectiveness depends on population density (e.g., competition, disease).

  • Density-Independent Factors:

    • Affect population regardless of density (e.g., natural disasters, climate).

  • Implications: Understanding these factors is critical for population management and conservation efforts.

11. Total Fertility Rate and Replacement-Level Fertility

  • Total Fertility Rate (TFR):

    • Definition: The average number of children born to a woman over her lifetime.

  • Replacement-Level Fertility:

    • Definition: The TFR at which a population remains stable, typically around 2.1 in developed countries.

12. Exponential vs. Logistic Growth

  • Exponential Growth:

    • Definition: Population growth with no limits, often leads to rapid increases when resources are abundant.

    • Graph: Characterized by a J-shaped curve.

  • Logistic Growth:

    • Definition: Population growth that slows as it approaches carrying capacity due to limited resources.

    • Graph: Characterized by an S-shaped curve.

  • Comparison: Different implications for resource management and ecological impacts.

13. Island Biogeography

  • Concept: The study of the ecological relationships and distributions of species on islands.

  • Factors Affecting Biodiversity:

    • Area: Larger islands tend to support more species.

    • Distance: Islands further from the mainland usually have lower biodiversity due to reduced immigration rates.

  • Applications: Understanding wildlife conservation strategies and habitat preservation.

14. Competition and Competitive Exclusion Principle

  • Competition: The interaction between species or individuals for limited resources (food, habitat, etc.).

  • Competitive Exclusion Principle: States that two species competing for the same resources cannot coexist at constant population values.

  • Implications: Highlights the importance of niche differentiation and resource management.

15. Symbiosis Types

  • Symbiosis: Any interaction between two species living together; can be beneficial, neutral, or harmful.

    • Types:
      a. Mutualism: Both species benefit (e.g., bees and flowers).
      b. Commensalism: One species benefits while the other is unaffected (e.g., barnacles on whales).
      c. Parasitism: One species benefits while harming the other (e.g., ticks on mammals).

16. Predation

  • Definition: The preying of one animal on another; a primary interaction in ecosystems.

  • Impacts: Helps regulate population sizes and maintain ecosystem balance.

  • Examples: Wolves preying on deer, hawks on mice.

17. Levels of Organization in the Biosphere

  • Levels:

    1. Individual: A single organism.

    2. Population: A group of individuals of the same species living in an area.

    3. Community: Different populations interacting in a given area.

    4. Ecosystem: A community and its physical environment interacting as a system.

    5. Biome: A large region characterized by similar climate and ecosystems.

    6. Biosphere: The global sum of all ecosystems.

18. Niche

  • Definition: The role or function of an organism within an ecosystem, including its habitat, resource use, and interactions with other species.

  • Importance: The concept of niches is crucial for understanding biodiversity and ecological relationships.

19. Differences in Developing and Developed Countries that Affect Population

  • Key Differences:

    • Access to healthcare, education, and economic opportunities influences birth and death rates.

    • Cultural norms surrounding family size and contraception play critical roles.

  • Implications: These differences affect global population trends and resource distribution.

20. Human Activities Caused by Rapid Development that Affect Biodiversity

  • Activities:

    • Urbanization, deforestation, pollution, and resource extraction.

  • Consequences: Loss of habitats, extinction of species, and disruption of ecosystems.

  • Importance: Understanding these activities is vital for implementing sustainable development practices and conservation efforts.