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Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Environmental Health Science · 300 Level
This is the complete lecture note for EVM 306 Population and environmental change, prepared for Environmental Health Science students at 300 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Series 1 Course code: EVM 306 Course title: Population and Environmental Change Course credit load: 2 Units List of Series: Series 1: Understanding Environmental Components Series 2: Interactions within Ecosystems and Habitats Series 3: Population Growth and Environmental Change Series 4: Patterns and Trends in Human Population Series 5: Implications of Population on the Environment Series Outline for Series 1: Understanding Environmental Components Part 1 (1.1): Defining the Environment and Its Major Components o Sub-Part 1.1.1: Definition and scope of the environment o Sub-Part 1.1.2: The physical components: land, water, and atmosphere Part 2 (1.2): Biological and Human Components of the Environment o Sub-Part 1.2.1: The biological component: flora and fauna o Sub-Part 1.2.2: The human component and its role in the environment Part 3 (1.3): Interaction Among Environmental Components o Sub-Part 1.3.1: How environmental components interact and depend on each other o Sub-Part 1.3.2: Natural cycles linking environmental components Part 4 (1.4): Human Alteration of Environmental Components o Sub-Part 1.4.1: Ways in which human activities alter environmental components o Sub-Part 1.4.2: Consequences of human alteration for environmental balance
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction The environment within which human populations exist is not a single, uniform entity but a complex arrangement of interacting components that together sustain life on Earth. Land, water, the atmosphere, living organisms, and human societies each constitute distinct elements of the environment, and the relationships among them determine the conditions under which populations can grow, thrive, or face constraints. Before examining how population change affects and is affected by the environment, it is essential to understand what the environment is composed of and how its components relate to one another. The aim of this Series is to introduce you to the major components of the environment, examine how these components interact with one another through natural processes and cycles, and consider the ways in which human activities alter environmental components and disrupt the balance among them. We shall commence this Series by defining the environment and identifying its physical components, namely land, water, and atmosphere. Next, we will examine the biological and human components and the roles they play. We will then explore how these components interact through natural processes and cycles. Finally, we will consider the ways in which human activities alter environmental components and the consequences of such alteration for environmental balance and population well-being. Series Learning Outcomes Upon completing this Series, you should be able to: SLO 1.1 define the environment and identify its major physical components, SLO 1.2 describe the biological and human components of the environment and explain their significance, SLO 1.3 explain how environmental components interact and are linked through natural cycles, SLO 1.4 identify the ways in which human activities alter environmental components, and SLO 1.5 assess the consequences of human alteration of environmental components for environmental balance. 1.1 Defining The Environment And Its Major Components 1.1.1 Definition and scope of the environment The environment refers to the sum total of all conditions, both physical and biological, that surround and influence living organisms. It encompasses all the external forces, substances, and conditions that affect organisms directly or indirectly, including soil, water, air, climate, and
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS other organisms. The scope of the environment is broad: it ranges from the microenvironment immediately surrounding an individual organism to the global environment, and from purely natural settings to those significantly modified by human activities. Understanding the environment as a system of interacting components is fundamental to the study of how populations exist within and alter their surroundings. Fill in the blank: The environment refers to the sum total of all __________, both physical and biological, that surround and influence living organisms. 1.1.2 The physical components: land, water, and atmosphere The three major physical components of the environment are land, water, and atmosphere. Land refers to the solid surface of the Earth, comprising rocks, soils, and landforms. It provides the physical substrate on which terrestrial life depends and supplies essential nutrients through weathering and decomposition. Water covers about 71 percent of the Earth's surface and is indispensable for all biological processes. The atmosphere is the envelope of gases surrounding the Earth that provides oxygen and carbon dioxide for living processes, regulates surface temperature, and shields organisms from harmful solar radiation. Together, these three physical components form the abiotic foundation of the environment. Fill in the blank: The three major physical components of the environment are land, water, and __________. Short description: A landscape photograph showing land, water, and sky together as the three physical components of the environment. Plate 1.1 The three physical components of the environment: land, water, and atmosphere
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Pilot questions 1.1 1. Which of the following best describes the environment? 2. Which of the following is a physical component of the environment? 3. What percentage of the Earth's surface does water cover? 4. Name the three major physical components of the environment. 5. Why is it important to understand the environment as a system of interacting components? 1.2 Biological And Human Components Of The Environment 1.2.1 The biological component: flora and fauna The biological component of the environment comprises all living organisms, including plants, animals, fungi, bacteria, and other microorganisms. Flora refers collectively to all plant life in a given area, which performs critical functions such as photosynthesis, oxygen production, soil stabilisation, and provision of food and habitat for other organisms. Fauna refers to animal life, which contributes to ecosystem functioning through pollination, seed dispersal, nutrient cycling, and regulation of plant and prey populations. Together, flora and fauna form the biotic layer of the environment that interacts continuously with the physical components. Fill in the blank: The collective term for all plant life in a given area, which performs functions such as photosynthesis and soil stabilisation, is __________. Short description: A photograph showing a diverse tropical forest with visible plant life and animals, representing the biological component of the environment.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Plate 1.2 The biological component of the environment: flora and fauna in a tropical forest 1.2.2 The human component and its role in the environment The environment operates through natural cycles, such as the water cycle, carbon cycle, and nutrient cycles. These cycles ensure the continuous renewal of resources and maintain balance in ecosystems. For instance, the water cycle circulates water between land, atmosphere, and oceans, while the carbon cycle regulates greenhouse gases. Disruption of these cycles often leads to environmental challenges such as climate change or soil degradation. Fill in the blank: As human populations grow, the human component exerts an increasing influence on all other environmental components, reshaping land use, altering water systems, and reducing __________. Short description: A diagram showing the four components of the environment, namely land, water, atmosphere, and the biological and human components, and the interactions among them. Figure 1.1 The major components of the environment and their interactions Pilot questions 1.2 1. What does the term fauna refer to? 2. Which of the following is a function performed by flora in the environment?
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 3. How does the human component differ from other biological components of the environment? 4. Why does the human component become more significant as population grows? 5. Give one example of how human activity alters the biological component of the environment. 1.3 Interaction Among Environmental Components 1.3.1 How environmental components interact and depend on each other The components of the environment do not exist in isolation but interact continuously, each influencing and depending on the others. Land provides the substrate for plant growth and shapes drainage patterns that determine water availability. Water regulates temperature, transports nutrients, and sustains biological activity across terrestrial and aquatic habitats. The atmosphere supplies gases essential for life and moderates the climate that determines where and how biological organisms can survive. Interdependence among components means that a change in any one of them produces effects that ripple through the entire system, affecting all other components and the organisms that depend on them. Fill in the blank: The property of environmental components whereby a change in one produces effects that spread through the entire system is known as __________. 1.3.2 Natural cycles linking environmental components Natural cycles are the processes that move matter and energy through the environmental components, maintaining the conditions for life. The water cycle moves water between the atmosphere, land, and water bodies through evaporation, condensation, precipitation, and runoff. The carbon cycle circulates carbon through the atmosphere, land, oceans, and living organisms via photosynthesis, respiration, and decomposition. The nitrogen cycle converts nitrogen
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