Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Define and identify biotic and abiotic factors.
• Explain how abiotic factors influence life in South African biomes.
• Describe how plants and animals adapt to their environment.
• Understand the interdependence within an ecosystem.
• Analyse the impact of human activities.

Lesson summary

This week, we delve deeper into the fascinating world of living organisms and their environments, focusing particularly on the interactions between biotic (living) and abiotic (non-living) factors. Understanding these interactions is crucial because it helps us appreciate the delicate balance of ecosystems in South Africa, from the bustling city parks to the vast African bushveld. We will explore how organisms adapt to their surroundings and how human activities can impact these environments. These concepts are vital for responsible citizenship, as they inform our choices about conservation and sustainability.

Lesson notes

2.1 Biotic and Abiotic Factors Biotic factors are all the living things in an ecosystem. This includes plants, animals, fungi, bacteria, and all other living organisms. They interact with each other in various ways, such as through competition for resources, predator-prey relationships, and symbiotic relationships. Abiotic factors are the non-living components of an ecosystem. These include sunlight, water, temperature, soil type, air, and minerals. Abiotic factors influence the types of organisms that can survive in a particular environment.

Example: In a South African grassland ecosystem, the biotic factors would include grasses, zebras, lions, insects, and bacteria. The abiotic factors would include sunlight, rainfall, temperature, soil nutrients, and wind. 2.2 The Influence of Abiotic Factors Sunlight: Sunlight is crucial for photosynthesis, the process by which plants convert light energy into chemical energy. The amount of sunlight available affects the distribution of plants. For example, the dense forests of the Drakensberg mountains receive less direct sunlight than the open grasslands of the Free State, leading to different plant communities.

Water: Water is essential for all living organisms. The availability of water influences the types of plants and animals that can survive in a particular area. In arid regions like the Karoo, plants have adaptations to conserve water, such as succulent leaves and deep roots. Animals also exhibit water-saving adaptations.

Temperature: Temperature affects the rate of biological processes. Different organisms have different temperature tolerances. Some organisms thrive in hot temperatures (e.g., desert plants), while others prefer colder temperatures (e.g., alpine plants in the Drakensberg). The distribution of species is heavily influenced by temperature patterns.

Soil: Soil provides nutrients and support for plants. Soil type affects the types of plants that can grow in an area, which in turn influences the types of animals that can live there. For example, sandy soils drain quickly and are low in nutrients, while clay soils retain water and nutrients but can be poorly drained.