Section B: The Living World
Aperçu
Cut a tropical rainforest down and the soil underneath is almost worthless within three or four harvests. That single fact confuses more students than any other in this section, because everything about a rainforest looks rich: the tallest trees on Earth, more species than anywhere else, rain almost every afternoon. The wealth is real. It is just not in the ground. It is in the living things, and when they go it goes with them.
In this lesson you will learn to read an ecosystem as a system: what feeds what, what recycles what, and what happens when a single component is pulled out. Then you will apply that to the two ecosystems this specification names. You will study a tropical rainforest in enough detail to use it as a case study, watch what deforestation does to it and weigh the strategies meant to slow it. And you will cross to the opposite extreme, the hot desert, where the limit is water rather than nutrients, and see how the fringes of those deserts are turning into desert themselves.
Objectifs
- Ecosystems exist at a range of scales and involve the interaction between biotic and abiotic components.
- Tropical rainforests Tropical rainforest ecosystems have a range of distinctive characteristics.
- Deforestation has economic and environmental impacts.
- Tropical rainforests need to be managed to be sustainable.
- Hot deserts Hot desert ecosystems have a range of distinctive characteristics. of climate, water, soils, plants, animals and people; how plants and
- Areas on the fringe of hot deserts are at risk of desertification.
- An example of a small-scale ecosystem to illustrate the concept of interrelationships within a natural system, an understanding of producers, consumers, decomposers, food chain, food web and nutrient cycling. The balance between components. The impact on the ecosystem of changing one component. An overview of the distribution and characteristics of large-scale natural global ecosystems.
- The physical characteristics of a tropical rainforest.
- The interdependence of climate, water, soils, plants, animals and people. How plants and animals adapt to the physical conditions. Issues related to biodiversity. Changing rates of deforestation.
- A case study of a tropical rainforest to illustrate:
- causes of deforestation - subsistence and commercial farming, logging, road building, mineral extraction, energy development, settlement, population growth
- impacts of deforestation - economic development, soil erosion, loss of biodiversity, contribution to climate change. Value of tropical rainforests to people and the environment.
- Strategies used to manage the rainforest sustainably - selective logging and replanting, conservation and education, ecotourism and international agreements about the use of tropical hardwoods, debt reduction.
- The physical characteristics of a hot desert; the interdependence
- animals adapt to the physical conditions.
- Issues related to biodiversity. Use examples to illustrate:
- Causes of desertification - climate change, population growth, removal of fuel wood, overgrazing, over-cultivation and soil erosion.
- Strategies used to reduce the risk of desertification - water and soil management, tree planting and use of appropriate technology.
Carte mentale
Ce theme est schematise pour montrer comment les idees se relient.
Ouvrez la carte mentale dans l'application
Note de cours
Fiche complete disponible sur l'application Green Bridge
Installez l'application Green Bridge CBT sur votre telephone ou votre ordinateur pour acceder a toute la bibliotheque IGCSE : sujets d'examen, baremes, cartes mentales, fiches memo et lecons audio.
Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur Section B: The Living World. Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à lépreuve. Cette section propose une variété de pratiques des questions conçues pour renforcer votre compréhension et vous aider à évaluer votre compréhension de la matière.
Vous rencontrerez un mélange de types de questions, y compris des questions à choix multiple, des questions à réponse courte et des questions de rédaction. Chaque question est soigneusement conçue pour évaluer différents aspects de vos connaissances et de vos compétences en pensée critique.
Utilisez cette section d'évaluation comme une occasion de renforcer votre compréhension du sujet et d'identifier les domaines où vous pourriez avoir besoin d'étudier davantage. Ne soyez pas découragé par les défis que vous rencontrez ; considérez-les plutôt comme des opportunités de croissance et d'amélioration.
- Which one of the following is a producer in an ecosystem? A. A fungus B. A grazing antelope C. A green plant D. A soil bacterium Answer: C
- Which soil type is typical of a tropical rainforest? A. Chernozem B. Latosol C. Podzol D. Peat Answer: B
- What is the maximum annual rainfall normally used to define a hot desert? A. 100 mm B. 250 mm C. 500 mm D. 1000 mm Answer: B
- Which of the following is a cause of desertification rather than a strategy to reduce it? A. Building stone lines along the contour B. Planting shelter belts of trees C. Using solar cookers instead of fuel wood D. Grazing more animals on the same land Answer: D
- Why do many rainforest trees have buttress roots? A. To store water for the dry season B. To support a tall tree whose roots are shallow C. To shed heavy rain from the trunk D. To reach groundwater many metres down Answer: B
Travaillez ces questions dans l'application
Travaillez ces questions dans l'application
Livres recommandés
Pratiquez des questions blanches
Vous voulez vous entraîner sur des questions blanches sur Section B: The Living World ? Téléchargez lapplication Green Bridge CBT pour accéder à des questions blanches et à des évaluations complètes sur ce sujet.
Téléchargez l'application sur Google Play.
Tout ce dont vous avez besoin pour exceller au JAMB, WAEC et NECO.
