Lesson Notes By Weeks and Term v4 - SHS 2
Ecology
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Ecology
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Subject: Biology
Class: SHS 2
Term: 2nd Term
Week: 12
Grade code: 2.3.2.LI.2
Strand code: 3
Sub-strand code: 2
Content standard code: 2.3.2.CS.1
Indicator code: 2.3.2.LI.2
Theme: Diversity of living things and their environment
Subtheme: Ecology
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Welcome, students! Today, we are exploring one of the most fascinating topics in biology: adaptation. Have you ever wondered why a Tilapia can only survive in water, while a grasscutter thrives on land? Or why some trees in the Northern Region look so different from those in the Kakum National Park? The answer is adaptation. Adaptation explains how living things develop special features that allow them to survive and thrive in their specific homes. Understanding this helps us appreciate the incredible diversity of life here in Ghana and why it is so important to protect our natural environments, from the coastal lagoons of Ada to the savannahs of Mole National Park.
A. Fundamental Definitions Habitat: This is the natural home or specific place where an organism lives. It provides the organism with food, water, shelter, and a place to reproduce. *Example:* The habitat of a Tilapia is a freshwater body like the Volta Lake. The habitat of an Acacia tree is the Guinea Savannah. Environment: This includes all the living (biotic) and non-living (abiotic) factors in an organism's surroundings. *Biotic factors:* Predators, prey, parasites, competitors. *Abiotic factors:* Temperature, water availability, sunlight, soil type, pH. Adaptation: An adaptation is any inherited characteristic (a feature or a behaviour) that increases an organism's ability to survive and reproduce in its specific environment. It is the result of evolution by natural selection over many generations. B. Types of Adaptations
We can classify adaptations into three main types. An organism usually has a combination of all three. Structural (or Morphological) Adaptations These are physical features of an organism's body. They are parts of the body structure. Example 1: The Tilapia (in a freshwater pond/lake) Streamlined Body: Its body is tapered at both ends. This shape reduces water resistance, allowing it to swim fast to catch food and escape predators. Gills: Possesses gills with a large surface area rich in blood capillaries. This is a highly efficient structure for extracting dissolved oxygen from the water for respiration. Fins (Pectoral, Dorsal, Caudal): The caudal fin (tail fin) provides powerful propulsion, while other fins are used for steering, balancing, and stopping. Lateral Line: A sensory organ running along the side of the body that detects vibrations and pressure changes in the water, helping it to locate prey and avoid obstacles. Example 2: The Acacia Tree (in the dry Savannah) Thorns: These are modified branches that protect the tree from being eaten by herbivores (e.g., goats, antelopes). Deep Taproot System: It has a long main root that grows deep into the soil to absorb water from underground sources, which is crucial during the long dry season. Small Leaves (Pinnate leaves): The small size of the leaflets reduces the surface area exposed to the sun and wind, minimizing water loss through transpiration. Physiological (or Functional) Adaptations These are related to the internal processes and functions of an organism's body. They are about how the body *works*. Example 1: The Grasscutter / Akranteɛ (in grasslands and farms) Specialised Digestive System: It has a digestive system with microorganisms in its caecum that can break down the tough cellulose in grass and cane stalks, allowing it to get energy from food that other animals cannot digest. Efficient Kidney Function: Like many mammals in warm climates, it has kidneys that are very good at reabsorbing water, producing concentrated urine to conserve water. Example 2: The Mangrove Tree (in coastal lagoons/swamps) Salt Tolerance: Mangroves grow in salty (brackish) water. They have physiological mechanisms to either filter out salt at the roots or excrete excess salt through their leaves. This allows them to survive in a habitat that would kill most other plants. Behavioural Adaptations These are the actions or patterns of activity of an organism that help it to survive. Example 1: The Agama Lizard (common around homes and rocks) Basking: It is cold-blooded (ectothermic). In the cool morning, it will sit on a rock or wall in the sun to absorb heat and raise its body temperature to become active. Shade-seeking: During the hottest part of the day (mid-day sun), it will retreat into the shade or a crevice to avoid overheating. This is a behaviour that helps regulate its body temperature. Example 2: The Giant African Snail (in forests and gardens) Aestivation: During the harsh dry season when food and moisture are scarce, the snail seals the opening of its shell with a layer of dried mucus (called an epiphragm) and becomes dormant. This behaviour allows it to conserve water and energy until the rains return. Nocturnal Activity: Snails are mostly active at night or on cloudy, wet days. This behaviour helps them avoid dehydration from the sun and escape daytime predators like birds.
Guided Practice (With Solutions)
Instructions: Let's work through these questions together as a class. I will ask for your ideas before we reveal the answer.