Biodiversity and Land Use

This page focuses on the importance of biodiversity and the impacts of human activities on ecosystems, a crucial topic in Topic 7 Biology AQA A Level.

Definition: Biodiversity refers to the variety of all species of organisms on Earth or within a specific ecosystem.

The importance of biodiversity is emphasized, highlighting its role in maintaining ecosystem stability and species interdependence.

Factors reducing biodiversity include:

• Population growth
• Increased standard of living
• Pollution (land, air, and water)
• Waste management issues
• Land use changes (e.g., building, quarrying, landfill)

Highlight: Understanding the factors affecting biodiversity is crucial for addressing conservation challenges and is frequently assessed in AQA GCSE Biology Ecology past papers.

The page details various types of pollution and their impacts on ecosystems:

1. Land pollution: Toxic chemicals entering food chains
2. Air pollution: Smoke particles and acidic gases causing acid rain
3. Water pollution: Pesticides, herbicides, sewage, and fertilizers contaminating water systems

Example: Pesticides entering water systems can accumulate in food chains, affecting multiple species and reducing biodiversity.

Predator-Prey Cycles and Sampling Techniques

This section explores the dynamic relationship between predators and prey, as well as methods for studying ecosystem populations.

Predator-prey feeding cycles demonstrate the interdependence of species within an ecosystem. As prey populations increase, predator populations follow suit due to increased food availability. However, this leads to increased predation, causing the prey population to decline, which in turn affects the predator population. This cyclical relationship is a key concept in understanding ecosystem dynamics.

Example: The classic example of the predator-prey cycle is the relationship between lynx and snowshoe hares in North America, often featured in predator-prey graph explanations.

Sampling techniques are crucial for assessing organism abundance in ecosystems:

1. Quadrats: Square frames used to count plants or slow-moving organisms
2. Transects: A measuring tape with quadrats placed at regular intervals

Highlight: Proper sampling techniques are essential for accurate ecological studies and are often tested in AQA Biology Ecology exam questions.

The page also introduces three important environmental cycles:

1. The water cycle
2. The decay cycle
3. The carbon cycle

These cycles illustrate the movement of matter and energy through ecosystems and are fundamental to understanding global ecological processes.

Adaptations and Extremophiles

This page delves into how organisms adapt to their environments, a crucial concept in AQA Biology Ecology exam questions.

Adaptations are features that enhance an organism's survival in its specific environment. They can be categorized into three types:

1. Structural adaptations: Physical characteristics
2. Behavioral adaptations: Actions an organism takes to survive
3. Functional adaptations: Internal processes that aid survival

Example:

• Structural: A polar bear's thick fur for insulation
• Behavioral: A lizard basking in the sun to regulate body temperature
• Functional: Some fish producing antifreeze proteins to survive in cold waters

Extremophiles are organisms that thrive in extreme conditions, such as high temperatures, high pressure, or high salt concentrations.

The page also introduces food chains, which illustrate feeding relationships within a community. Food chains always begin with producers (typically plants) and progress through primary consumers, secondary consumers, and sometimes tertiary consumers.

Highlight: Understanding food chains is essential for grasping energy flow and trophic levels in ecosystems, a key topic in AQA GCSE Biology Ecology past papers.