Lesson Notes By Weeks and Term v4 - SHS 1
ECOLOGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
ECOLOGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Biology
Class: SHS 1
Term: 2nd Term
Week: 9
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
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
In our communities, no one lives completely alone. A farmer depends on a driver to transport produce, the driver depends on a mechanic to fix the car, and the mechanic depends on the farmer for food. This web of connections is called interdependence, and it is exactly how nature works. In the environment, from the smallest insect to the largest Odum tree, every living thing is connected. This lesson will explore these connections, showing how organisms rely on each other for food, shelter, and survival.
This topic focuses on the central idea of Interdependence: the way living organisms (biotic factors) rely on each other and their physical environment (abiotic factors) for survival. An organism cannot exist in isolation.
A. Foundational Terms Ecosystem: A biological community of interacting organisms and their physical environment. Example: The Kakum National Park, the Weija Dam, or even a small pond behind your house. Community: All the different populations of different species living and interacting in an area. Example: In a garden, the community includes the hibiscus plants, lizards, bees, earthworms, and weeds. Population: A group of organisms of the same species living in the same area at the same time. Example: All the tilapia in a pond; all the mango trees in an orchard.
B. Types of Interdependence (Interactions) We can classify the interactions between organisms based on their outcomes. We will use symbols to represent the outcome: (+) The organism benefits. (-) The organism is harmed. (0) The organism is not significantly affected. Symbiosis (Living Together) Symbiosis describes any long-term, close relationship between two different species. Mutualism (+/+) Definition: A relationship where both organisms benefit. Explanation: This is a "win-win" situation. Both partners gain something essential for their survival or reproduction. Ghanaian Examples: Bees and Shea Trees: The bee gets nectar (food) from the shea flower. In the process, the bee carries pollen from one flower to another, allowing the shea tree to be pollinated and produce the valuable shea nuts. Both the bee (gets food) and the tree (gets to reproduce) benefit. Nitrogen-fixing Bacteria and Legumes: Bacteria (like *Rhizobium*) live in the root nodules of leguminous plants like groundnuts or beans. The plant provides shelter and food (sugars) for the bacteria. In return, the bacteria convert nitrogen gas from the air into nitrates, a form of fertilizer the plant can use to grow. Both benefit. Cattle Egrets and Cattle: You often see white birds (egrets) near cattle. The cattle's movement through the grass disturbs insects, making them easy for the egrets to catch for food. The egrets, in turn, may eat ticks and other parasites off the cattle's skin, providing a cleaning service. Commensalism (+/0) Definition: A relationship where one organism benefits, and the other is neither harmed nor helped. Explanation: One partner gets a clear advantage, while the other is largely unaffected. Ghanaian Examples: Ferns/Orchids on a Cocoa Tree: Many smaller plants like ferns and orchids grow on the branches of large trees like cocoa, odum, or mango trees. They do this to get better access to sunlight high up in the canopy. The fern benefits (gets sunlight), but the large tree is generally not harmed or helped by its presence. Remora Fish and Shark: In the ocean, the Remora fish has a sucker on its head to attach itself to a shark. The Remora gets a free ride and feeds on the scraps of food left over when the shark makes a kill. The shark benefits (+), while the shark is not affected (0). Parasitism (+/-) Definition: A relationship where one organism (the parasite) benefits by living on or inside another organism (the host), which is harmed. Explanation: The parasite takes nutrients from the host, weakening it and sometimes causing disease or death. A successful parasite usually does not kill its host quickly, as it depends on the host for survival. Ghanaian Examples: *Plasmodium* and Humans (Malaria): The *Plasmodium* parasite is the organism that causes malaria. It lives inside the human host's red blood cells and liver, causing fever, chills, and sickness. The mosquito is a vector that transmits the parasite. The parasite benefits (+) by reproducing, while the human host is harmed (-). Tapeworm and Humans/Livestock: A tapeworm lives in the intestines of an animal or human, absorbing digested food directly from the host. The tapeworm benefits (gets food and shelter), while the host is harmed (loses nutrients, may lose weight and become weak). Tick on a Goat: A tick attaches to a goat's skin and sucks its blood for food. The tick benefits (+), while the goat is harmed (-) through blood loss and potential disease transmission. Predation (+/-) Definition: An interaction where one organism (the predator) hunts, kills, and eats another organism (the prey). Explanation: This is a short-term, direct interaction, unlike parasitism. Predation is a crucial process for controlling population sizes and maintaining the health of an ecosystem. Ghanaian Examples: Hawk and Chicken: A hawk (predator) swoops down to catch and eat a chicken (prey) in a compound. Lion and Antelope: In Mole National Park, a lion (predator) hunts an antelope (prey). Praying Mantis and Grasshopper: A praying mantis (predator) ambushes and eats a grasshopper (prey). Competition (-/-) Definition: An interaction where two or more organisms require the same limited resource, such as food, water, sunlight, or space. Explanation: Because the resource is limited, the presence of one organism reduces the amount available for the other. Therefore, this interaction is negative for both competitors, as their growth, survival, or reproduction may be reduced. Intraspecific competition: Between members of the *same* species. Interspecific competition: Between members of *different* species. Ghanaian Examples: Maize Plants in a Crowded Farm (Intraspecific): If a farmer plants maize seedlings too close together, they will all compete for the same limited water, sunlight, and soil nutrients. As a result, none of the plants will grow as tall or produce as much maize as they would if they had more space. Both are negatively affected. Lizards and Geckos (Interspecific): Both Agama lizards and house geckos might compete for the same insects (like ants and moths) around a house light at night. The success of one species in catching insects reduces the food available for the other. Decomposition (Nutrient Cycling) Definition: The process by which dead organic matter (dead plants, animals, waste) is broken down into simpler substances. Key Organisms: Decomposers (mainly bacteria and fungi). Explanation & Outcome: This is a fundamental form of interdependence. When a plantain leaf falls or an animal dies, decomposers go to work. They consume the dead matter, releasing essential nutrients like nitrates and phosphates back into the soil. These nutrients are then absorbed by living plants, allowing them to grow. Without decomposers, nutrients would remain locked up in dead bodies, and life would eventually cease. Ghanaian Example: When you leave plantain peels in a pile in the garden, over time they turn into dark, rich soil. This is the work of fungi and bacteria. This compost can then be used to fertilize new yam or cocoyam plants. The fungi and bacteria get food (+), and the entire ecosystem benefits from the recycled nutrients.
Guided Practice (With Solutions)