The Living World: Senior Cycle Biology · 5th Year · Ecology and Environmental Biology · Summer Term

Ecosystems and Biotic/Abiotic Factors

Students will define ecosystems and identify the key biotic (living) and abiotic (non-living) factors that influence them.

• NCCA Curriculum Specifications
• NCCA: Senior Cycle - Ecology
• NCCA: Senior Cycle - The Study of Life

About This Topic

Ecology is the study of how organisms interact with each other and their environment. This topic focuses on the flow of energy through ecosystems via food chains and webs, and the cycling of essential nutrients like carbon and nitrogen. Students learn about trophic levels and why energy is lost at each stage, limiting the length of food chains. The NCCA curriculum emphasizes the importance of biodiversity and the roles of producers, consumers, and decomposers.

Understanding these dynamics is crucial for grasping how ecosystems function and how they respond to changes. Students also explore the concept of a niche and the importance of keystone species. This topic comes alive when students can physically model the patterns of energy flow and participate in collaborative investigations of local Irish habitats.

Key Questions

1. Differentiate between biotic and abiotic factors and their interactions within an ecosystem.
2. Explain how abiotic factors like temperature and light influence the distribution of organisms.
3. Analyze the interdependence of living and non-living components in a local ecosystem.

Learning Objectives

• Classify specific components of a local Irish ecosystem as either biotic or abiotic.
• Explain the interdependence between at least two biotic factors and two abiotic factors within a given ecosystem.
• Analyze how changes in an abiotic factor, such as light intensity, would affect the distribution of organisms in a specific habitat.
• Compare and contrast the roles of producers, consumers, and decomposers within an ecosystem.
• Design a simple experiment to test the effect of an abiotic factor on a biotic component of an ecosystem.

Before You Start

Introduction to Biology: Cells and Organisms

Why: Students need a foundational understanding of what constitutes a living organism before they can identify and classify biotic factors.

Basic Chemistry: Properties of Water

Why: Understanding the unique properties of water is essential for comprehending its role as a critical abiotic factor in aquatic and terrestrial ecosystems.

Key Vocabulary

Ecosystem	A community of living organisms (biotic) interacting with their non-living physical and chemical environment (abiotic).
Biotic Factors	The living or once-living components of an ecosystem, such as plants, animals, fungi, and bacteria.
Abiotic Factors	The non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems, such as temperature, sunlight, water, and soil.
Habitat	The natural home or environment of an animal, plant, or other organism, defined by its specific biotic and abiotic conditions.
Niche	The role and position a species has in its environment, including how it meets its needs for food and shelter, how it survives, and how it reproduces.

Watch Out for These Misconceptions

Common Misconception

Students often think that 'decomposers' are not part of the food web or are less important.

What to Teach Instead

Decomposers are essential for recycling nutrients back into the soil for producers. Including them in every food web activity and discussing what would happen without them helps emphasize their vital role.

Common Misconception

There is a belief that energy is 'recycled' in an ecosystem just like nutrients are.

What to Teach Instead

Nutrients cycle, but energy flows in one direction and is eventually lost as heat. Using a 'one-way street' vs. 'roundabout' analogy for energy and nutrients can help clarify this fundamental difference.

Active Learning Ideas

Simulation Game: The Energy Pyramid Game

Students use tokens to represent energy units. They pass tokens from 'producers' to 'consumers,' with 90% being 'lost' (put in a bin) at each step to demonstrate why top predators are rare.

40 min·Whole Class

Inquiry Circle: Food Web Construction

Groups are given cards representing organisms from a specific Irish ecosystem (e.g., a rocky shore or a woodland). They must build a complex food web and then predict what happens if one species is removed.

45 min·Small Groups

Gallery Walk: Nutrient Cycle Posters

Students create detailed posters of the Carbon and Nitrogen cycles. They then move around the room to identify where bacteria, plants, and animals play their roles in each cycle.

40 min·Small Groups

Real-World Connections

• Environmental consultants working for Bord na Móna assess the impact of peatland restoration projects on native flora and fauna, considering factors like water levels and soil composition.
• Marine biologists studying the coast of Ireland, like those at NUI Galway, investigate how changes in ocean temperature and salinity affect the distribution of fish populations and seaweed beds.
• Farmers in County Cork manage their dairy herds by considering abiotic factors such as rainfall patterns and soil pH, which influence grass growth, a primary food source for their livestock.

Assessment Ideas

Quick Check

Provide students with a list of items found in a local park (e.g., oak tree, squirrel, rock, stream, sunlight, earthworm, fallen leaves). Ask them to categorize each item as biotic or abiotic and briefly explain their reasoning for two items.

Discussion Prompt

Pose the question: 'Imagine a prolonged drought in an Irish woodland. Which abiotic factors would be most immediately affected, and how would these changes impact the biotic components, such as insects and birds?' Facilitate a class discussion where students share their predictions.

Exit Ticket

Ask students to write down one biotic factor and one abiotic factor from a specific Irish ecosystem (e.g., a salt marsh in Wexford). Then, have them describe one way these two factors interact and influence each other.

Frequently Asked Questions

How can active learning help students understand ecosystem dynamics?

Active learning turns abstract cycles into visible connections. By building food webs and simulating energy loss, students see the interdependence of species and the physical constraints on life. Collaborative mapping of nutrient cycles helps them identify the specific biological and chemical processes involved. These activities encourage students to think systemically about nature, which is essential for understanding ecological stability and change.

What is a trophic level?

A trophic level is the position an organism occupies in a food chain, such as producer, primary consumer, or secondary consumer.

Why is only about 10% of energy passed from one trophic level to the next?

Most energy is used by the organism for its own life processes (like movement and heat production) or is lost as waste; only a small amount is stored in tissues to be eaten.

What is the role of nitrogen-fixing bacteria in the nitrogen cycle?

These bacteria convert atmospheric nitrogen gas into nitrates in the soil, which plants can then absorb and use to make proteins.