Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Define habitat, population, community, and ecosystem with South African examples.
• Describe the roles of producers, consumers, and decomposers.
• Explain the interdependence of organisms, including symbiotic relationships.
• Identify different types of ecosystems in South Africa.

Lesson summary

This week, we delve deeper into the fascinating world of living organisms and their environments. We'll be focusing on how organisms interact with each other and their surroundings within specific ecosystems. Understanding these interactions is crucial because it helps us appreciate the delicate balance of nature and understand the impact of human activities on our South African landscapes and communities. From the plants in your backyard to the animals in Kruger National Park, every organism plays a vital role. By studying ecosystems, we can better protect our biodiversity and natural resources for future generations.

Lesson notes

2. 1.

Levels of Organisation in Ecology: Individual Organism: A single living thing (e.g., a single Impala, a single Acacia tree).

Population: A group of individuals of the same species living in the same area at the same time (e.g., a herd of Impala living in Kruger National Park, all the Acacia trees in a specific area of the Savanna).

Community: All the different populations of organisms living and interacting in a particular area (e.g., the Impala population, the Acacia tree population, the lion population, the grass population – all interacting in the Savanna).

Ecosystem: The community of living organisms (biotic factors) plus the non-living (abiotic) factors in their environment, interacting as a system (e.g., the Savanna ecosystem includes the Impala, Acacia trees, lions, grass, plus the soil, water, sunlight, and temperature).

Habitat: The natural home or environment of an animal, plant, or other organism. This can be a specific location or area within an ecosystem (e.g., The Acacia tree provides a habitat for birds and insects; The river is the habitat for the fish).

Example: Consider a school garden.

An individual organism: One tomato plant.

A population: All the tomato plants.

A community: The tomato plants, the earthworms, the snails, the grasshoppers.

An ecosystem: The community + the soil, the sunlight, the rain.

Habitat: The soil around the tomato plants is the habitat for the earthworms. 2.

2. Feeding Relationships: Every organism needs energy to survive. Energy flows through an ecosystem through feeding relationships.

Producers (Autotrophs): These are organisms that make their own food through photosynthesis. They use sunlight, water, and carbon dioxide to create sugars (energy). Plants are the main producers. Examples in South Africa include grass in the grasslands, trees in the forests, and algae in rivers and oceans.

Consumers (Heterotrophs): These are organisms that cannot make their own food and must obtain energy by eating other organisms.

Herbivores: Eat only plants (e.g., Zebras, Giraffes, Springbok).

Carnivores: Eat only animals (e.g., Lions, Leopards, Snakes).

Omnivores: Eat both plants and animals (e.g., Baboons, Pigs, Humans).

Scavengers: Consume dead animals that they did not kill themselves (e.g., Vultures, Hyenas).

Decomposers (Saprotrophs): Break down dead organisms and waste material into simpler substances. This process releases nutrients back into the soil, which are then used by producers. Examples include bacteria and fungi. Without decomposers, nutrients would be locked up in dead organisms, and the ecosystem would eventually run out of essential elements.

Food Chains and Food Webs: Food Chain: A simple linear sequence showing the transfer of energy from one organism to another when one organism eats another.

Example: Grass → Springbok → Cheetah Food Web: A complex network of interconnected food chains in an ecosystem. Food webs show the more realistic and complex feeding relationships in an ecosystem. Most animals eat more than one type of food, and many are eaten by more than one type of predator.