Lesson Notes By Weeks and Term v4 - SHS 1
ECOLOGY
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ECOLOGY
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Subject: Biology
Class: SHS 1
Term: 2nd Term
Week: 7
Grade code: 1.3.2.LI.2
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.2.CS.2
Indicator code: 1.3.2.LI.2
Theme: DIVERSITY OF LIVING THINGS AND THIER ENVIRONMENT
Subtheme: ECOLOGY
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Welcome, students! Today, we are diving into one of the most exciting topics in Biology: Ecology. Look around our school compound. You see birds, insects, trees, grasses, and maybe even a lizard. Have you ever wondered if they need each other to survive? The answer is a big YES! In nature, no living thing is an island. From the tiny bacteria in the soil to the giant Odum tree, all life is connected in a complex web. Understanding this "interdependence" is crucial because it explains how our farms produce food, how our forests stay healthy, and why protecting our environment in Ghana is so important for our own survival.
A. Fundamental Terms Ecology: The scientific study of how living organisms interact with each other and with their non-living environment (like sunlight, water, and soil). Ecosystem: A community of living organisms (biotic factors) interacting with their non-living environment (abiotic factors). For example, the Weija Dam is an aquatic ecosystem, and the Achimota Forest is a terrestrial ecosystem. Interdependence: This is the core idea for today. It means that living organisms in an ecosystem rely on each other for survival. If one part of the system is removed or changes, it affects many others. Think of it like a football team – the goalkeeper depends on the defenders, who depend on the midfielders to get the ball to the strikers. If one player is removed, the whole team is affected. B. Types of Interactions and Their Outcomes
Living things interact in various ways. These interactions are the building blocks of interdependence. We can classify them based on whether the organisms benefit, are harmed, or are unaffected.
We use symbols to make this easier: (+) = The organism benefits. (-) = The organism is harmed. (0) = The organism is neither helped nor harmed. Mutualism (+/+) Definition: A relationship where both organisms benefit. Ghanaian Example 1: Bees and Mango Flowers. Interaction: The bee visits the mango flower to drink nectar (sweet liquid), which is its food. As the bee feeds, pollen from the flower sticks to its body. When the bee flies to another mango flower, this pollen is transferred, allowing the flower to be pollinated. Outcome: The bee gets food (+) to survive. The mango flower gets pollinated (+), which leads to the development of a mango fruit. The wider outcome for the ecosystem is food for humans and other animals, and the continuation of the mango tree species. Ghanaian Example 2: Cattle and Egrets (Cattle Birds). Interaction: You often see white birds (egrets) walking alongside cattle. The cattle's movement through the grass disturbs insects, making them fly up. The egrets can then easily catch and eat these insects. Outcome: The egret gets an easy meal (+). The **cattle benefits (+) because the egrets may also eat ticks and other parasites off its skin. Commensalism (+/0) Definition: A relationship where one organism benefits, and the other is unaffected (neither helped nor harmed). Ghanaian Example 1: Orchids growing on a Cocoa Tree. Interaction: An orchid (a type of flowering plant) grows on the high branches of a cocoa tree. Outcome: The orchid benefits (+) by getting closer to the sunlight, which it needs for photosynthesis. The cocoa tree is not affected (0); the orchid doesn't take nutrients from it, it just uses it for support. Ghanaian Example 2: A lizard hiding under a log. Interaction: A lizard escapes the hot sun or a predator by hiding under a dead log. Outcome: The lizard benefits (+) by getting shelter and protection. The dead log is unaffected (0). Parasitism (+/-) Definition: A relationship where one organism (the parasite) benefits, while the other (the host) is harmed. The parasite lives on or inside the host. Ghanaian Example 1: Plasmodium (Malaria Parasite) and Humans. Interaction: The *Plasmodium* parasite is transmitted into a human's bloodstream by an Anopheles mosquito. The parasite lives and reproduces inside the human's red blood cells and liver. Outcome: The parasite benefits (+) by getting food and a place to live and multiply. The human host is harmed (-), suffering from the disease malaria, which causes fever, weakness, and can be fatal. Ghanaian Example 2: Tick on a Goat. Interaction: A tick attaches itself to a goat's skin and sucks its blood for food. Outcome: The tick benefits (+) by getting a blood meal. The goat is harmed (-); it loses blood, can become weak, and the tick can transmit diseases. Predation (+/-) Definition: An interaction where one organism (the predator) hunts, kills, and eats another organism (the prey). Ghanaian Example 1: Hawk and a Chick. Interaction: A hawk (predator) swoops down and catches a young chicken (prey) for food. Outcome: The hawk benefits (+) by getting a meal. The chick is harmed (-) as it is killed. Wider Ecosystem Outcome: Predation helps to control the population of prey animals. Without predators, the number of chickens or grasscutters could increase so much that they eat all the available food and then starve. Predators help maintain a balance. C. The Critical Role of Decomposers Interaction: When plants and animals die, organisms like bacteria and fungi (e.g., mushrooms) feed on the dead organic matter. This process is called decomposition. Outcome: This is a vital outcome for all life. Decomposers are nature's recyclers. They break down complex materials in dead bodies into simple nutrients (like nitrates, phosphates). These nutrients are returned to the soil, making it fertile. Plants then absorb these nutrients through their roots to grow. Without decomposers, the world would be covered in dead bodies, and the soil would run out of nutrients for farming. D. Thought Experiment: What if Organisms Lived Alone? Let's imagine a world without interdependence, as suggested by the NaCCA exemplar. If there were no bees (pollinators): Mango, orange, and cashew trees would not produce fruit. Our food supply would drastically reduce. If there were no decomposers (bacteria/fungi): Dead leaves, animals, and faeces would pile up everywhere. The soil would become barren and infertile, and farming would be impossible. If there were no predators (hawks, snakes): The population of rats and other rodents would explode. They would destroy our farms, eat our stored food, and spread diseases.
Conclusion: The outcome of interdependence is a balanced, stable, and productive ecosystem. The outcome of isolation is ecosystem collapse, starvation, and extinction.