Biotic Factors

Understanding the living components of ecosystems and their interactions

CAPS Grade 10 Life Sciences

Biotic factors are the living parts of an ecosystem. Learners need to know the difference between producers, consumers, and decomposers, and explain how these organisms depend on one another.

1. Producers (Autotrophs)

Producers, also known as autotrophs, are the foundational elements of every food chain. They are termed "self-feeders" because they can produce their own food using sunlight.

Role: Producers convert radiant energy from the sun into chemical potential energy in the form of glucose through the process of photosynthesis.

Examples of Producers

Green Plants

The most common producers, utilizing sunlight to create energy.

Algae

Aquatic producers that contribute significantly to oxygen production and serve as food for various organisms.

Photosynthetic Bacteria (Cyanobacteria)

Microscopic organisms that also perform photosynthesis and are vital in many aquatic ecosystems.

2. Consumers (Heterotrophs)

Consumers are organisms that cannot synthesize their own food and must rely on other living organisms for energy. They are categorized into several groups based on their dietary habits:

Primary Consumers (Herbivores)

These organisms feed exclusively on plants.

Examples: Zebra, Grasshopper
Secondary Consumers (Carnivores/Omnivores)

These consumers eat primary consumers. They can be either carnivorous or omnivorous.

Examples: Lion (carnivore), Jackal (omnivore)
Tertiary Consumers (Top Predators)

These are the apex predators in an ecosystem, feeding on secondary consumers.

Example: Martial Eagle
Scavengers

Scavengers consume dead animals, playing a crucial role in the ecosystem by cleaning up carcasses.

Examples: Vulture, Hyena

Consumer Pyramid

Tertiary Consumers (Martial Eagle)
Secondary Consumers (Lion, Jackal)
Primary Consumers (Zebra, Grasshopper)
Producers (Green Plants, Algae)

Simple Food Chain

Grass (Producer) → Zebra (Primary Consumer) → Lion (Secondary Consumer)

Quick Check: Identify the Consumer

Question 1/4

1. A zebra feeds exclusively on grass. What type of consumer is it?

A Secondary Consumer
B Primary Consumer
C Tertiary Consumer
D Scavenger

3. Decomposers (Saprotrophs)

Decomposers are vital for recycling nutrients within ecosystems. They break down dead plant and animal matter into simpler inorganic substances, which are then reintroduced into the soil.

Role: Decomposers facilitate the recycling of nutrients, ensuring that essential elements like nitrogen and phosphorus are available for producers.

Bacteria

Microorganisms that decompose organic matter and are essential for nutrient cycling.

Fungi

Organisms that break down complex organic materials, contributing to soil fertility.

Note: Without decomposers, nutrients would remain trapped in dead organisms, leading to soil infertility and a breakdown of the ecosystem's health.

4. Biotic Interactions (Symbiosis)

The CAPS curriculum emphasizes the importance of understanding how living factors interact with one another. These interactions can be categorized as follows:

Mutualism

In this interaction, both species benefit from the relationship.

Example: Bees and flowers, where bees obtain nectar while helping flowers with pollination.
Commensalism

One species benefits while the other remains unaffected.

Example: Remora fish attach to sharks, gaining protection and food scraps without harming the shark.
Parasitism

One organism (the parasite) benefits at the expense of the other (the host), which is harmed.

Example: Ticks feeding on a dog.
Competition

Organisms compete for the same resources, such as food, water, or mates.

Predation

One organism (the predator) hunts and kills another (the prey).

Matching Game: Symbiosis Interactions

Match each interaction type with its correct description and example.

Matches: 0/5
Interaction Types
Mutualism
Commensalism
Parasitism
Competition
Predation
Descriptions & Examples
Both species benefit (Bees and flowers)
One benefits, other unaffected (Remora and shark)
One benefits at host's expense (Ticks on dog)
Organisms compete for same resources
One hunts and kills another (Lion and zebra)

True or False Quiz

1. Producers convert radiant energy from the sun into chemical energy through photosynthesis.

2. Scavengers are organisms that hunt and kill their prey.

3. Decomposers break down dead organic matter and recycle nutrients back into the soil.

4. In mutualism, one organism benefits while the other is harmed.

5. Cyanobacteria are photosynthetic bacteria that act as producers in aquatic ecosystems.

Fill in the Blanks

1. Organisms that produce their own food using sunlight are called _______________.

2. A relationship where both species benefit is called _______________.

3. Fungi and bacteria that break down dead organic matter are called _______________.

Exam Tip

When preparing for exams, be aware that you may be asked to identify the roles of these biotic factors within specific South African ecosystems, such as the Savanna. Additionally, you might need to explain the importance of decomposers in the nitrogen or carbon cycles, highlighting their role in maintaining ecosystem health and nutrient availability.

Key Terms

Biotic Producers Autotrophs Consumers Heterotrophs Herbivores Carnivores Omnivores Scavengers Decomposers Saprotrophs Mutualism Commensalism Parasitism Competition Predation

What To Remember

Biotic factors include producers, consumers, and decomposers. Learners should also know the main relationships between organisms, such as mutualism, parasitism, competition, and predation, because these are often tested in food chains and food webs.