IB Environmental Systems and Societies TEST 05 Study Guide PDF

ENVIRONMENTAL SYSTEMS AND SOCIETIES/ENVIRONMENTAL SCIENCE STUDY GUIDE TEST 05 Subtopic 2.1. Individuals, populations, communities, and ecosystems; Subtopic 8.1. Human Populations; Subtopic 2.2...

ENVIRONMENTAL SYSTEMS AND SOCIETIES/ENVIRONMENTAL SCIENCE STUDY GUIDE TEST 05 Subtopic 2.1. Individuals, populations, communities, and ecosystems; Subtopic 8.1. Human Populations; Subtopic 2.2. Energy and Biomass in Ecosystems YOU WILL NEED A CALCULATOR FOR THIS TEST IB SL ESS OBJECTIVES: Build a food chain using a food web. o Food chains will be a straight, horizontal line with one organism per trophic level (usually 3-5 levels), with arrows showing the energy transfer as the higher level eats the lower level. o From food webs, such look for one clear path that begins with a producer, that isn’t shown to be eating any living thing, to the secondary or tertiary consumer at the top, with no arrows indicating that it’s being eaten. o EX: Explain what will happen when one species is added or removed from a food web. o In any case, it disrupts the balance of the ecosystems, which impacts populations, resource availability and interactions between different factors in the ecosystem – it will always be a cascading effect, where all animals in that food web will be affected. → it can cause chain reactions throughout the food web, affecting biodiversity, population dynamics, and ecosystem stability. o Removed: a) Loss of food source for some organisms (may decline)  b) Predator-prey imbalance (predator is removed, prey increases and uses up more resources which creates a lack of resources for other species, and if a prey is removed, the predator may decline due to lack of food). c) As all animals are affected, there can be a decrease in biodiversity due to these factors. o Added: a) New competition = it may outcompete native species for food and habitat, potentially leading to population declines or extinctions. b) Predation changes = if the species is a predator, it may decrease populations of existing prey species. If it’s a new prey species, predator populations might grow. c) Ecosystem overload/collapse = invasive species can disrupt chains or webs, leading to resource depletion, habitat destruction or spread of diseases. Outline the strengths and weaknesses of models. o Can Vary from model to model (some can have more specific information to evaluate). Strengths Weaknesses Easier to work with Low accuracy (simplified) Used to predict the effect of a change of input Wrong assumptions = wrong model Applied to other similar situations Inaccurate predictions See patterns Don’t consider all variables Visualize small items/entities May show different effects using the same data Predict further into the future = uncertain May be interpreted in different ways Distinguish between community and ecosystem. o Community = ecological concept that refers to an ecosystem with interacting populations, meaning the biotic factors in that area. o Ecosystem = ecological concept that refers to a complex system made of populations that interact with one another and with their physical surroundings (abiotic) factors as well. Define keystone species. o Keystone species = type of species that maintain structure in the ecosystem in which it lives, ultimately having a disproportionate impact on the community structure, and increasing the risk of ecosystem collapse if they are removed. Outline factors that explain variations in human population (factors that will increase and decrease it). o Migration = more people entering the country, increasing the population size. o Birth rates = higher birth rates in comparison to death rates can increase population size.  - Low birth rates = fewer people of childbearing age (more elders - HICs), improved family planning, urbanization, anti-natal policies (could only have a certain number of children), pension schemes, taxes being higher for more children, more independence/education for women. - High birth rates = more people of childbearing age (LICs), agricultural development/better public health/sanitation lower DR and stimulate high population growth (affecting fertility and increasing births), lowering income tax, free education/healthcare, replace children who die, prestige, continue the family name. o Death rates − Low death rates = fewer people of older age groups (more of younger generations - LICs), clean water, reliable good supply, hygiene/sanitation, lower population densities, better healthcare, rising standards of living. − High death rates = more people of older age groups (HICs), higher rate of infectious diseases, overcrowding, poverty, lack of safe conditions. o Life expectancy = if it’s higher, more people live longer, which can increase population size, as others continue to be born and grow – vice versa if it’s lower. Outline economic, social, and environmental implications of an increasing or decreasing human population. o Economic − Increasing population = economic growth (more workers/consumers can boost economic productivity and demand for products), unemployment and poverty (job competition increases, leading to higher unemployment and income inequality). − Decreasing population = less resource pressure (lower demand for resources can reduce costs and overexploitation), declining markets (reduced consumer demand can shrink economies, affecting businesses and investments). o Social − Increasing population = cultural diversity/innovation (more people contribute to new ideas, technologies and cultural exchanges), overcrowding and social inequality (not enough space for everyone in housing, so homelessness increases for certain groups of people). − Decreasing population = better living standards (fewer people could mean improved access to resources and services), aging population burden (fewer young people supporting retirees can stress healthcare and pension systems). o Environmental − Increasing population = potential for innovation in sustainability (more people may lead to advancements in renewable energy, conservation, etc.), higher demand for natural resources (depletion of resources from ecosystems).  − Decreasing population = natural habitat recovery (less pressure on resources and land allows ecosystems to regenerate), declining workforce for conservation (fewer people working in sustainability and conservation efforts). Outline advantages and disadvantages of modelling human population growth. Advantages Disadvantages Allow us to predict the growth of the future global Assumes that human behavior is the same throughout human population. the years (predictable). Help support economic development by estimating Doesn’t account for sudden events, like pandemics or workforce growth, consumer demands, and so on. natural disasters, that can affect population growth. Helps assist in managing natural resources efficiently by It simplifies complex interactions between social, predicting demand and potential shortages. cultural, economic and political factors. Can help identify areas of potential overpopulation or Limited by data quality, as incomplete/outdated data resource scarcity, which can help increase aid in those can lead to incorrect models/predictions. areas. Explain why it is difficult to estimate human carrying capacity. o It is ultimately because of the broad and changing ecological niche of humans, potentially creating a change in our carrying capacity. We are rapidly changing and evolving, so any estimate can only work during the short-term. Like everyone else, humans have limiting factors, but at the same time, we have temporarily eliminated most of them with our developments, meaning that we are living beyond the limits of sustainability. We use a greater range of resources than other species, we substitute resources with others if the originals run out, large predators that eat humans have been eliminated, developments in technology lead to changes in resources we use, we have such different lifestyles that cannot be generalized, and so on. Describe ways to change human carrying capacity (either increase or decrease it). o Developing technological advancements (increase) = new ways for us to expand resources, increasing our life span, etc. o Expanding the use of resources (increase) = the range of resources used by humans is much greater than any other species, and when resources are limited, humans tend to find substitutes for them, extending their availability. → can be decreased through reusing (used more than once), recycling (material is reused for different products), remanufacturing (material is reused to make a similar product), and absolute reduction (using fewer resources). o Reducing the usage of energy control in nonrenewable resources and minimize usage of renewable ones (self-sufficiency) – decrease. o Decrease (external) = pandemics, famine, natural disasters, climate change. Describe the different stages of the DTM model.  o DTM model = escribes the changing levels of births and deaths in a human population through different stages of development over time. a) Stage 1 = PRE-INDUSTRIAL SOCIETIES = high/variable BR/DR, population growth fluctuates (but low), short life expectancies, no countries (only some indigenous tribes) still at this stage. b) Stage 2 = EARLY EXPANDING LICs = BR remains high but death rate comes down rapidly, life expectancy slightly increases, population growth is rapid. c) Stage 3 = LATE EXPANDING IN WEALTHIER LICs = BR drops and DR remains low, population growth continues but at a smaller rate. d) Stage 4 = LOW STATIONARY HICs = BR/DR are low/variable, population growth fluctuates (but stable), higher dependency ratio, longer life expectancy, most developed countries are at this stage. e) Stage 5 = DECLINING HICs = BR is lower than DR (rising), long life expectancy, population declines. Calculate NIR, and DT. o NIR = natural increase rate = rate of human growth expressed as a % change per year = Crude birth rate−crude death rate 10 70 o DT = doubling time = years it takes for a population to double in size at its current growth rate = 𝑁𝐼𝑅 Outline strengths and limitations of the DTM. Strengths Limitations Very easy to understand. Deaths from infectious diseases or other pandemics may also affect the model. Shows simple change over time. Eurocentric model that assumes all countries will become industrialized, which may not be the case. Can be easily compared between different countries Fall in DR is not always that steep. across the world. Shows how population and development go hand in Some countries/regions have compressed time scale of hand. these changes, which the model doesn’t account for. State factors that allow countries to move from one stage of the DTM to another. 1) Improvements in healthcare. 2) Urbanization/industrialization.  3) Economic development/rising incomes. 4) Improvements to public sanitation. 5) Better overall living conditions. 6) Political stability and reduced conflict. 7) Access to education for all. 8) Increased agricultural productivity. Outline the processes of photosynthesis and respiration (including their inputs and outputs). o Photosynthesis = day process that turns light energy to chemical energy in the form of glucose that autotrophs depend on to thrive/live. - Inputs = 6𝐶𝑂2 + 6𝐻2 𝑂 = carbon dioxide and water - Outputs = 6𝑂2 + 𝐶6 𝐻12 𝑂6 = glucose and oxygen o Respiration = process by which glucose is broken down to release ATP (energy) for living processes, such as movement. − Inputs = 6𝑂2 + 𝐶6 𝐻12 𝑂6 = glucose and oxygen − Outputs = 6𝐶𝑂2 + 6𝐻2 𝑂 = carbon dioxide and water Outline the role of producers, decomposers, and consumers in ecosystems. o Producers = 1st trophic level, autotrophs (make their own food – plants, algae, bacteria) → provide energy for all other trophic levels, provide habitats with niches (increasing biodiversity), supply nutrients to soil, bind soil, and stop erosion. o Decomposers = bacteria/fungi (obtain nutrients by secreting enzymes that break down organic matter) → break down dead organisms, release nutrients back into the cycle, control the spread of disease. o Consumers = 2-4 trophic levels, heterotrophs → keep each other in check through negative feedback (herbivory – predation and competition), disperse seeds, pollinate flowers, remove weak/old/sock individuals from populations. Explain why the quantity of energy transferred decreases along a food chain. o 2nd Law of Thermodynamics = as energy is transferred, it is degraded to a less useful form of energy, such as heat, which is then then lost, meaning that part of the energy doesn’t go to the next level because it’s not useful. → energy loss as heat. o There are also other reasons for trophic inefficiency = not everything is eaten, digestion is inefficient (food lost in feces), some energy assimilated is used in reproduction/other life processes. State the ways by which solar energy reaching producers is lost from an ecosystem before it turns into biomass available for the next trophic level. o Of the solar energy that reach a plant, some of it is immediately reflected and some of it doesn’t enter the plant, as some wavelengths are unsuitable. Some will also be transmitted through the leaf and out the other side, rather than being absorbed.  o The energy that does enter the cell is transformed into chemical energy through photosynthesis, but part of that energy is lost in respiration. Define biosphere integrity and suggest strategies used to protect that same integrity. o Biosphere integrity = overall health and function of ecosystems and the biodiversity they support. Some strategies to protect this, especially from humans, include: a) Preservation of natural habitats, as they are home to a wide range of species. b) Provide essential ecosystem services, ultimately assuring the availability of suitable habitats/resources to support the continued survival/reproduction of species. c) Implementing sustainable land/resource management = preventing habitat damage, waste, supporting ethical fishing/forestry practices, and implementing sustainable agriculture approaches. d) Education/public awareness = motives people to become environmental stewards and take action to protect/restore ecosystems and their local communities. Using a forest as an example, describe how ecosystem sustainability can be lost due to human activities, like logging and agriculture. o In forests, with these practices, the dense tree canopies are lost, and the layered structure reduced, which leads to a loss of habitats and diversity, as there are less plants, which leads to less niches, and then less biodiversity. The forest floors will also be exposed to sunlight/rain, which can make it dry out or wash away nutrients. Loss of tree cover means less transpiration of water vapor as well, which leads to less rainfall and cooling. Now, forests also become more vulnerable when conditions change. o Overall, forests would become dominated by various plant species suited to drier conditions, nutrient cycling patterns will be altered and there’ll be changes in general ecosystem structure and function. Define TFR. o Total fertility rate = average number of children each woman has over her lifetime. - Replacement fertility = 2.1 (average) = number of children each woman should have to maintain the population growth rate at 0. - FR = number of births per 1000 women of childbearing age (15-44). Provide reasons for a high and for a low fertility rate. o Fertility rates = higher fertility rates compared to death rates can increase population size. − Reasons for higher fertility rate (mostly in LICs) = high infant/childhood mortality, cultural/societal choices, more children mean more income for families (as more children can work to support the family), more children means that there will be more care for the parents when they grow old, security in old age, status in women, unavailability of contraceptives, inheritance (need to have male heir). − Lower fertility rates = provide education (literacy), improve health (no disease spread, better nutrition, provided medication/vaccines), contraceptives are available, higher income for individual families, greater resource management in the country.  Referring to examples, explain how countries can increase their population by resorting to pro-migration and pro-natalist policies. Singapore in 1987 after the anti-natalist policies Their population had began to shrink too much, so they introduced the pro-natalist policies, that encouraging women to have more children to rise the population, which was done through increasing the time for maternity leave and making it free for the first 4 children, increasing child benefits to reduce financial concerns, government-subsidized childcare, discouraging family planning or abortion, government- sponsored dating agencies, and so on. Even if in Singapore, it was as successful as the government assumed because women felt like they had more freedom so they purposefully decided not to have as many kids, it can still be a way to increase population size. Germany’s recent changes in laws to attract migrant Germany became more pro-immigration mainly to labor address workforce shortages, ultimately contributing to a growing population, countering previous concerns about demographic decline. To do this, they simplified the process for a visa for skilled workers, they shortened residency requirements, allowing for dual citizenship (which encouraging them to stay longer), they recognized foreign qualifications (making it easier for migrants to work in their fields), they increased those workers’ economic benefits and social welfare, and so on. By doing this, foreigners were attracted and more began to come to Germany, increasing population size. PRACTICE EXERCISES → ESS Past Papers