Science · Year 7 · The Art of Classification · Term 1

Biodiversity and Ecosystems

Students will investigate the concept of biodiversity and its importance within various ecosystems.

• ACARA Content Descriptions
• AC9S7U02

About This Topic

Biodiversity encompasses the variety of living organisms within an ecosystem, including species richness, genetic variation, and habitat diversity. In Year 7, students explore how this variety contributes to ecosystem stability by examining food webs, nutrient cycling, and resilience to disturbances. For instance, diverse ecosystems recover faster from events like bushfires, a relevant example in Australia.

This topic aligns with AC9S7U02, building on classification skills from the unit to analyze human impacts such as habitat fragmentation from urban development or invasive species introduction. Students assess consequences of losing keystone species, like the Tasmanian devil in its habitat, which disrupts predator-prey balances and leads to trophic cascades.

Active learning shines here because students can conduct schoolyard biodiversity audits or simulate ecosystem changes with manipulatives. These approaches make complex interdependencies visible, foster collaboration in data analysis, and connect abstract ideas to observable local environments, deepening understanding and retention.

Key Questions

1. Explain the relationship between biodiversity and ecosystem stability.
2. Assess the impact of human activities on local biodiversity.
3. Predict the consequences of losing a keystone species in an ecosystem.

Learning Objectives

• Classify organisms from local ecosystems based on observable characteristics and introduce binomial nomenclature.
• Explain the interconnectedness of organisms within a food web and predict the impact of removing a producer or consumer.
• Analyze the effect of human activities, such as deforestation or pollution, on the biodiversity of a specific Australian ecosystem.
• Evaluate the importance of biodiversity for ecosystem resilience using examples like the Great Barrier Reef or a local woodland.
• Design a simple model illustrating how a keystone species, like the quokka, contributes to the stability of its habitat.

Before You Start

Classifying Living Things

Why: Students need foundational knowledge of how to group and identify organisms based on observable characteristics to understand biodiversity.

Introduction to Food Chains

Why: Understanding the basic flow of energy in a food chain is essential before exploring the complexity of food webs and ecosystem interactions.

Key Vocabulary

Biodiversity	The variety of life in a particular habitat or ecosystem. This includes the diversity of species, the genetic variation within those species, and the diversity of ecosystems themselves.
Ecosystem	A community of living organisms interacting with each other and their physical environment. This includes both biotic (living) and abiotic (non-living) components.
Food Web	A network of interconnected food chains showing the feeding relationships between different organisms in an ecosystem. It illustrates the flow of energy.
Keystone Species	A species that has a disproportionately large effect on its natural environment relative to its abundance. Its removal can cause significant changes to ecosystem structure.
Habitat Fragmentation	The process by which large, continuous habitats are broken up into smaller, isolated patches. This often results from human activities like road construction or urban development.

Watch Out for These Misconceptions

Common Misconception

All species in an ecosystem are equally important.

What to Teach Instead

Keystone species have outsized roles in maintaining structure; most contribute subtly. Role-playing food webs helps students see disproportionate effects of removal through group predictions and discussions.

Common Misconception

Ecosystems remain stable without biodiversity.

What to Teach Instead

Diversity buffers against changes like disease; low diversity leads to collapse. Hands-on simulations where students remove species reveal cascading failures, correcting static views via observation.

Common Misconception

Human activities only reduce biodiversity locally.

What to Teach Instead

Impacts cascade globally through interconnected systems. Mapping local-to-global chains in collaborative audits builds this understanding, as students link schoolyard data to broader patterns.

Active Learning Ideas

Field Survey: Schoolyard Biodiversity Audit

Students divide the school grounds into quadrants and record species observed, categorizing by plants, insects, and birds. They tally diversity indices and discuss stability factors. Groups present findings with photos or sketches.

50 min·Small Groups

Simulation Game: Keystone Species Removal

Provide food web cards for a local ecosystem like a woodland. Students remove a keystone species card and predict chain reactions by rearranging connections. They draw before-and-after diagrams to visualize impacts.

30 min·Pairs

Model Building: Ecosystem Balance Jars

Students layer soil, plants, decomposers, and predators in jars to mimic ecosystems. They observe changes over a week, noting biodiversity roles, then perturb one jar by removing a species and compare outcomes.

45 min·Small Groups

Formal Debate: Human Impact Scenarios

Assign scenarios like logging or pollution to groups. Students research local examples, argue effects on biodiversity, and propose solutions. Whole class votes on best mitigation strategies.

40 min·Whole Class

Real-World Connections

• Conservation biologists working for organizations like the World Wildlife Fund (WWF) Australia conduct biodiversity surveys in areas like the Daintree Rainforest to monitor species health and identify threats.
• Urban planners in cities such as Melbourne use biodiversity assessments to guide development, ensuring green spaces and wildlife corridors are incorporated to maintain ecological balance.
• Farmers in regional Australia may consult with ecologists to implement sustainable practices that protect local biodiversity, such as maintaining native vegetation along waterways to support insect populations.

Assessment Ideas

Quick Check

Present students with a simplified food web diagram of a local Australian ecosystem. Ask them to identify one producer, one primary consumer, and one secondary consumer. Then, pose the question: 'What might happen if all the [specific animal] disappeared?'

Discussion Prompt

Facilitate a class discussion using the prompt: 'Imagine a new housing development is planned for an area with diverse native plants and animals. What are two potential negative impacts on biodiversity, and what is one strategy to minimize these impacts?'

Exit Ticket

Students receive a card with the term 'Keystone Species'. Ask them to write: 1. A one-sentence definition in their own words. 2. An example of a keystone species and its role in its ecosystem.

Frequently Asked Questions

What is the role of keystone species in biodiversity?

Keystone species disproportionately influence ecosystem structure despite low numbers, like dingoes controlling herbivore populations in Australian bushlands. Their removal triggers trophic cascades, reducing overall biodiversity and stability. Students grasp this through simulations that reveal hidden dependencies.

How do human activities impact local biodiversity?

Activities like land clearing for agriculture fragment habitats, introduce invasives, and pollute waterways, lowering species diversity. In Australia, this affects unique ecosystems like the Great Barrier Reef. Monitoring school sites helps students quantify and propose local solutions.

How can active learning help teach biodiversity and ecosystems?

Active methods like biodiversity surveys and ecosystem models engage students kinesthetically, making interdependencies tangible. Group simulations of species loss reveal stability dynamics that lectures miss, while field data collection connects concepts to real Australian contexts, boosting retention and critical thinking.

Why does biodiversity support ecosystem stability?

Diverse species fill multiple roles in food webs and nutrient cycles, providing redundancy against disturbances. This resilience is evident in fire-adapted Australian eucalypt forests. Predicting outcomes from keystone loss in activities reinforces how variety prevents collapse.