Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Define 'environment', 'biotic', and 'abiotic' factors with South African examples.
• Identify biotic and abiotic components in an environment.
• Explain how abiotic factors affect living things.
• Distinguish between an organism, population, community, and ecosystem.
• Describe how living things depend on each other and their environment.

Lesson summary

Living organisms and their environments are deeply interconnected. Understanding these connections is crucial for managing our natural resources and ensuring a sustainable future for South Africa. From the majestic Kruger National Park to our urban gardens, every ecosystem plays a vital role. This week, we begin our journey into understanding the basics of ecosystems and how living things interact within them. We'll be looking at what makes up an environment, the difference between living and non-living components, and how they influence each other.

Lesson notes

What is an Environment? The environment encompasses everything that surrounds a living organism. It includes both living things (biotic factors) and non-living things (abiotic factors). Think of it like the setting of a story – it's not just the characters (living things), but also the scenery, the weather, and everything else that influences the characters' lives.

Biotic Factors: Biotic factors are all the living things in an environment. This includes plants, animals, fungi, bacteria, and any other living organism. In a South African context, biotic factors could include: Plants: Grasses in the savanna, trees in the forests (like the Knysna forest), fynbos in the Western Cape.

Animals: Lions in the Kruger National Park, fish in the oceans, birds in the sky, insects crawling on the ground.

Microorganisms: Bacteria in the soil helping to decompose organic matter, fungi helping tree roots absorb nutrients. These biotic factors interact with each other in various ways, such as through feeding relationships (who eats whom), competition for resources (like water or sunlight), and cooperation (like bees pollinating flowers).

Abiotic Factors: Abiotic factors are all the non-living things in an environment. They play a crucial role in determining which living things can survive in that environment.

Some key abiotic factors include: Sunlight: Provides energy for plants to perform photosynthesis (making their own food).

Water: Essential for all living things to survive. Different plants and animals have different water requirements. Think of a succulent plant that thrives in dry areas vs. a water lily in a pond.

Soil: Provides nutrients and support for plants. The type of soil (e.g., sandy, clay, loamy) affects which plants can grow there.

Temperature: Affects the rate of biological processes. Organisms have different temperature tolerances. Think about how some animals hibernate in winter to survive the cold.

Air (oxygen and carbon dioxide): Oxygen is needed by most organisms for respiration (breathing), while carbon dioxide is used by plants for photosynthesis. pH: Acidity or alkalinity of the soil and water. Different organisms have different pH tolerances.

Salinity: The amount of salt in the soil or water. This is especially important in coastal environments. Organism, Population, Community, and Ecosystem: These are different levels of organization in ecology: Organism: A single living thing (e.g., a single impala, a single baobab tree).

Population: A group of organisms of the same species living in the same area at the same time (e.g., a herd of impala in Kruger National Park, a group of baobab trees in Limpopo).

Community: All the different populations of different species living together in the same area and interacting with each other (e.g., all the plants, animals, fungi, and bacteria living together in a specific section of Kruger National Park).

Ecosystem: A community of living organisms (biotic factors) interacting with each other and with their non-living environment (abiotic factors) (e.g., the entire Kruger National Park, including all the plants, animals, fungi, bacteria, soil, water, sunlight, etc.).

Worked example

Example 1: The Veldt (Grassland)

Biotic Factors: Grasses, zebras, wildebeest, lions, termites, various insects, bacteria in the soil.

Abiotic Factors: Sunlight, water (rainfall), soil (nutrients, minerals), temperature, wind.

How they interact: Grasses use sunlight for photosynthesis. Zebras eat the grasses. Lions eat the zebras. Termites break down dead plant matter in the soil, returning nutrients to the soil. Rainfall determines how much grass can grow. Temperature affects the activity levels of animals.

Example 2: A Pond Ecosystem

Biotic Factors: Algae, water lilies, fish, frogs, insects, bacteria in the mud.

Abiotic Factors: Sunlight, water (amount, temperature), dissolved oxygen, pH of the water, minerals in the sediment.

How they interact: Algae use sunlight for photosynthesis, producing oxygen. Fish breathe the dissolved oxygen. Frogs eat insects. Bacteria decompose dead organisms at the bottom of the pond. The amount of sunlight affects the growth of algae and water lilies. The pH of the water affects the survival of fish.

Guided Practice (With Solutions)

Question 1:

Identify three abiotic and three biotic factors that you would find in a typical South African garden.

Solution:

Abiotic: Sunlight, Soil, Water

Biotic: Flowers, Grass, Earthworms