Summary and Exam Tips for Human Population
Human Population is a subtopic of Human influences on the environment, which falls under the subject Science in the IB MYP curriculum. A population is defined as a group of organisms of one species living in the same area at the same time. In contrast, a community includes all populations of different species within an ecosystem, which is a unit containing these organisms and their environment interacting together.
Factors affecting population growth include food supply, predation, and disease. Human population growth has been increasing exponentially over the last 150 years due to improved technology, medicine, hygiene, and healthcare, leading to a rapid increase in birth rates and a decrease in death rates.
The sigmoid growth curve describes population growth in four phases:
- Lag phase: Organisms adapt to the environment before reproduction.
- Log phase: Exponential growth occurs with abundant food supply and low death rates.
- Stationary phase: Population levels out as resources become limited.
- Death phase: Population decreases as death rates exceed birth rates due to limited resources or toxic waste buildup.
Natural environments often deviate from this curve due to factors like temperature changes, predators, disease, immigration, and emigration.
Exam Tips
- Understand Key Terms: Make sure you can define and differentiate between a population, community, and ecosystem.
- Focus on Growth Phases: Be able to identify and explain the four phases of the sigmoid growth curve and the factors influencing each phase.
- Graph Interpretation: Practice interpreting population growth graphs and diagrams, focusing on identifying the different phases.
- Limiting Factors: Be prepared to discuss how limiting factors like food supply, predation, and disease affect population growth.
- Read Carefully: Always read exam questions attentively and tailor your answers to the specific organism or scenario presented.
